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An Innovative Real Time Production Management System
                                                      A white paper


Abstract
Scheduling is indeed a major issue in all manufacturing and project execution facilities world over. It is also
recognized that if scheduling is efficient and automated huge benefits could result as existing resource usage can
be maximized allowing dramatic increase in number of orders processed at the same time substantially reducing
cost of production while ensuring reliability in delivery on the committed date. No wonder scheduling is a hot
research topic and the market is flooded with scheduling systems of sorts. Still a truly efficient and automatic
scheduling system remains an elusive dream.

This white paper lists the six important reasons why a scheduling system fails in real-life situations. It then
describes how a new scheduling system called Talika PMS satisfies all the six critical requirements in detail with real
data supporting the claims from its first major installation.

                                 Visit www.etalika.in for more information and free download

1 Introduction                                                     Before we elucidate more on the system features we
                                                                   would like to re-emphasis importance of scheduling
Day-to-day scheduling of any manufacturing facility                in any manufacturing facility and why current
is recognized to be the most important problem to                  solutions fail to address the problem correctly.
be solved. [1] D. Ouelhadj and S. Petrovic recent
[Oct 2008] study reveals that solutions based on                   2 Importance of scheduling
creation of a static schedule are impractical in real-
life situations and discusses several dynamic                      The only real differentiators to compete in
scheduling approaches only to conclude that more                   established products and services market are Cost
work is still needed in this field of research.                    and Reliable delivery. Quality of product / service is
                                                                   mostly considered a pre-condition to be in business
We wish to present here a complete dynamic real-                   rather than a differentiator. Both cost and reliable
time micro level scheduling system that is proven to               delivery of product / service are directly impacted by
work in the most complex manufacturing facilities. It              scheduling.
is a fully scalable, decentralized, multi-location and
user configurable system to suit any manufacturing /               2.1 Scheduling and cost of production
project environment. The core scheduling is fully
automatic and guarantees that all currently allotted               It is almost axiomatic to state that a major portion of
tasks in real-time can be executed with a complete                 cost of production (even exceeding 70% - 80% in
and detailed schedule prediction of all activities for             made-to-order industries) is expended in
all orders in-hand.       The system automatically                 coordinating and managing production activities vis-
reschedules in response to real-time events as                     à-vis the actual cost of value-addition involved.
notified by operators’ handling current tasks on the
shop floor, with an objective to maximize resource                 Most real life manufacturing involves execution of
utilization while minimizing job cycle time. It offers             several individual activities in a complex order to
full micro-level future schedule visibility of all                 create any saleable final product or service. The
running jobs to predict when each would be over                    starting point thus is in breaking down an order
given the current load as of NOW. The cycle of                     requirement into elemental activities that must be
allotting tasks, seeking task-wise feedback on                     completed in order to accomplish the final product /
allotments made from operators’ on shop floor, and                 service deliverable: ranging from getting inputs or
re-predicting its impact in subsequent reschedule                  raw material until final packing and dispatch. Unless
happen every minute 24x7.                                          this detailing is not done, actual value addition
                                                                   cannot begin. Once it is known “How” the order can
                                                                   be fulfilled the most difficult job of scheduling


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individual activities of orders begin. It primarily        seldom match reality        owing     to   unexpected
translates in deciding what activity must be done,         disruptions [3] & [5].
where it should be done (that is using what limited
resources) and when. One can refer to them as the          So, any scheduling system that fails to respond to
3W’s. Most expensive and competent personnel in            changing situation on ground by failing to reschedule
any manufacturing or project execution facility are        and redraw its prediction (Gantt chart) is a misfit in
engaged fully in the process of managing production        real life making purported schedule optimality and
that involves, breaking down order execution,              efficiency claims hypothetical.
estimating its cost, time and wastages, deciding
what activities to do now and next, taking feedback        3.2 No feedback mechanism
on progress made, follow-up and expediting to meet
deadlines. The whole exercise is repeated all over         A scheduling system can only be responsive to what
again by rescheduling to predict and monitor               is happening on the shop floor if a feedback
expected completion dates for all orders in hand.          mechanism exists. This feedback mechanism should
                                                           be both real-time and automatic. Peter Cowling and
Add to this already complex situation, the burden of       Marcus Johansson [2] argue in a well researched
estimating when new orders can be delivered given          paper that “in many production processes real time
the existing load of orders already in-hand. All this is   information may be obtained from process control
now possible to be completely automated resulting          computers and other monitoring systems, but most
in a substantial reduction in the cost of production.      existing scheduling models are unable to use this
                                                           information to effectively influence scheduling
2.2 Scheduling & reliability                               decisions in real time”. This is a major disconnect
                                                           making the schedule infeasible as it is soon out of
Scheduling decisions taken now directly impact             synchronization with reality.
expected completion times of all orders in-hand. In
real-life situations one has to deal with several          We have recognized that the only authentic real-
orders, each with its own set of individual                time source of feedback information from the shop
interdependent activities requiring a certain profile      floor is the personnel (Operators’) in charge of
of resources that are both shared and limited. It is       performing individual activities. However, each
well impossible, even in small setups, to manually         operator can only give feedback on what each one
figure-out impact of real-time decisions on predicted      does and that too ideally limited to the current task
completion dates.                                          in-hand.     We achieve a seamless feedback
                                                           mechanism to the scheduling engine by allocating
Honoring delivery on committed date is more                elemental executable tasks in real-time to individual
important than how fast one turns around an order          Operators, and seeking task-specific feedback for
in a manufacturing facility. It is only possible to do     each such allotted task. The process of task
so, if one is in a position to predict impact of all       allotment, progress feedback and subsequent
scheduling decisions taken now on all orders in-hand       reschedule to decide what to do next happens 24x7
in real time as an on-going process.                       automatically.

3 Why conventional scheduling systems fail in the          3.3 Schedule not actionable
real world?
                                                           The decision to execute an elemental task or activity
3.1 Static scheduling                                      of an order requires one to take into account several
                                                           aspects; availability of inputs, availability of
Scheduling is a widely misunderstood term. Many            resources and technical feasibility of performing the
believe plotting activities to be performed on             task. Most scheduling systems usually fail on this
different resources on a time scale (Gantt chart)          count. Proposed activities are either not actionable
make a schedule. Actually a Gantt chart is just a          or represent a group of activities leaving the decision
snap shot of what is likely to happen in the future        of what exactly to do now to the operators. In order
given the situation NOW. As one progresses in time         to circumvent this problem, many systems offer a
this representation will change because predictions        “drag & drop” facility to correct or manipulate
                                                           proposed schedule before it is released. As [4] P.

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                                                                                           © 2013, Laxman C Marathe
Velaga asserts, presence of a “drag & drop” facility      unaltered any amendment to future task listing in no
indicate an inherent weakness of the scheduling           way adds to nervousness. On the contrary, impact
logic.                                                    on completion dates of all jobs in hand must be
                                                          known immediately not when the next frozen
3.4 Manufacturing facilities are on-going concerns        schedule is created.

Getting new orders and completing existing orders is      We propose a true scheduling system called Talika
a continual process in real facilities.        Existing   Production Management System (PMS) that satisfies
commitments cannot generally be disturbed because         all the above primary requirements.
of new orders. Situations can become more complex
as orders could be cancelled or amended. Any              4 Overview of Talika PMS
scheduling solution that considers a static order load
is therefore impractical.                                 The system has a distributed architecture as
                                                          indicated in Figure-1. At the center is the real-time
3.5 Working in shifts                                     scheduling engine working round-the-clock and is
                                                          the live heart of the system. Several different types
Many manufacturing facilities work round the clock        of consoles interact with the scheduling engine using
in shifts manned by a different set of personnel.         a proprietary protocol that is robust and
Scheduling decisions impact across shifts and the         asynchronous making the entire process of
biggest challenge becomes information handover            communication absolutely safe.
between shifts. The only remedy is in having the
scheduling systems work 24x7 continuously.                There are several different types of consoles each
                                                          designed to perform a specific function on the shop
3.6 Stability versus responsiveness                       floor. Consoles work in a standalone mode but can
                                                          also communicate with the scheduling engine, if
Most scheduling systems provide a stable schedule         connected, making the entire distributed system live
frozen for a period (usually a few days) and expects      and reliable.      Exhibit–1 at the end details
it to hold well unless disruptions occur, which           functionality of each Console shown in Figure-1 and
inevitably do occur. It is reasoned that having a         explains how the automatic scheduling engine drives
continually changing schedule results in shop floor       other peripheral or support activities. Most ERP
nervousness. Shop floor nervousness is a myth             systems only handle the peripheral activities sans
propagated to hide inability of doing a quick             the driving scheduling engine at its heart, making it
reschedule. Operators’ are only concerned with the        more of a fancy carcass disconnected from the shop
task in-hand. As long as the current task remains         floor.




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Figure-1: Macro system schema

5 How the system works                                 One can also create part CT diagrams for
                                                       common work flows in the factory and save
Figure-2 gives an at-a-glance view of how the          them as sub-assemblies. Sub-assemblies are
entire system works.                                   building blocks one may use to quickly create a
                                                       new complex job definition.
5.1 Starting point
                                                       Jobs are stored as proprietary files with a
Job Study Wizard (JSW) is the starting point. As       default “*.tlk” extension to any media. One can
already explained each sales person or                 save, share and reuse stored jobs over and over
concerned agency can have a JSW of their own.          again just like a text file.
Potential enquiries can be quickly converted to a
detailed job definition depicted as an easy to         5.2 Scheduling a job
understand component task (CT) diagram. CT
diagram actually represents the micro level            It is not necessary all defined jobs be actually
activity work flow for creating one-something of       scheduled. Jobs could be defined when we
any value-added service or product. It is more         receive an enquiry to estimate its cost and
like a recipe. One can always scale it up or down      assess delivery date, but we only need to
to match extent of final output required keeping       schedule the order when it matures. When
the CT diagram (recipe) unchanged. It is also          scheduled, orders flow over to the scheduling
possible to create, as a one-time exercise, a          engine and the process of executing its
bank of most standard CT diagrams (standard            constituent tasks begin.
orders) used in the facility. So, defining new
orders may simply translate into picking up an         5.3 Role of scheduling engine and shop floor
appropriate or nearly matching already defined         interface: Work Center Console (WCC)
CT diagram and making minor adjustments to it.
                                                       Scheduling engine works 24x7 and proactively
                                                       controls all factory work centers at a micro level.


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                                                                                  © 2013, Laxman C Marathe
It decides what tasks of which orders can and            to the scheduling engine to be taken cognizance
should be actually allotted for execution to the         of during the next reschedule that happens
shop floor. Complete information of currently            every minute. This cycle of allotting tasks,
allotted tasks flows to the concerned WCC in             getting progress and completion notification
real-time.    Operators’ acknowledge allotted            feedback, and subsequent fresh allotment on
tasks to start execution and notify interim              each work center on the shop floor goes on
milestones achieved, until the allotted task is          without end.
not over. All notifications flow back in real-time




                                    Figure-2: Working principle at-a-glance


6 Working logic of scheduling engine

Scheduling engine comprises of a set of complex          the JSW itself. Only on confirmation, valid
daemons working round-the-clock.         Like a          orders are communicated to the scheduling
human scheduler does, it always decides what             engine. During order definition stage itself a lot
tasks to execute now. The entire optimization            of detailing about the job is done including de-
principle could be summed in one line as “if             selection of technically non-feasible work
something (read a task) can be done and it               centers to execute specific tasks of the job.
should be done then it will be done”. The above          User can also specify several guidelines for the
rule automatically guarantees that resource              scheduling engine to follow while executing the
utilization is maximized while simultaneously            order      called   “execution    preferences”.
reducing job cycle time.                                 Scheduling engine uses its own intelligence
                                                         while implementing user specified guidelines
An order is first broken-down to its elemental           but ensures they are honored whenever
tasks in form of a CT diagram during definition in       possible. Execution preferences are not rigid;

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they can be changed even at run-time after a             all tasks in an order. Table-1 below lists the
job is scheduled. Execution preferences could            execution preferences and explains what each
be different for each task. However, user can            means and how the scheduling engine uses
specify them just once with applicability                them while making allotment decisions.
controlled across parts or group of tasks or for

Table-1: Execution Preferences and what they mean
      Execution preference              What it means                  Scheduling engine usage
                                                                   If WIP is not on the critical
                               Attempt to minimize work-in-        chain and has enough time left
                               progress (WIP) from being           to be produced and used then
      WIP control
                               created too much in advance         its creation is deferred thereby
                               and thus remain unused.             minimizing WIP build-up on the
                                                                   shop floor.
                                                                   Tasks are allotted first by order
                                                                   priority and then by the future
                               User desires to change task
      Control    of   task                                         burden on the task within an
                               execution order, if necessary, at
      execution order                                              order.    However, user may
                               run-time.
                                                                   change this natural order of
                                                                   execution at run time.
                                                                   Scheduler tries to honors user
                                                                   preference with switchover
                                                                   savings, if any, considered. In
                               If one has a choice of work
                                                                   case the first preferred work
      Work center choice       centers to perform a task then
                                                                   center is unavailable it tries to
                               which one to choose?
                                                                   allot the task on the second
                                                                   preferred work center and so
                                                                   on.
                               Ensuring a particular task is       Always tries to execute the said
      Locking Option           only executed within a user         task within the specified period,
                               specified period.                   as far as possible.
                                                                   If the task is on the critical chain
                               Breaking up a task to run           or its execution cannot be
                               concurrently on more than one       deferred any further scheduling
      Auto-breaking option
                               work center with an intention       engine will try to optimize and
                               to reduce task execution time.      select the most appropriate
                                                                   breaking option possible.
                               Stop and resume task execution
                               after a holiday, recess period.     Scheduler wisely decides to
      Spanning Option          Commonly referred to as a non-      span or not to span depending
                               scheduling time zone (NSTZ) in      on the current situation.
                               the system.




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Execution preference            What it means                   Scheduling engine usage
                       It may not be necessary to wait
                       to start the next value-adding
                                                             Scheduler tries to begin the
                       task that uses or consumes
                                                             next value adding task even
                       what is produced by the current
                                                             before the earlier one feeding
                       task until the current task is not
                                                             into the next one is not yet
MCI option             over. One can overlap in time
                                                             over. Time to initiate the next
                       both tasks in order to expedite
                                                             task can be user decided or left
                       the order. We can say the
                                                             to the scheduling engine to
                       preceding task gives a mid-
                                                             figure out.
                       course intimation (MCI) to the
                       next task to begin.
                       User may want some           tasks
                       (orders) to be executed       only
                                                             Scheduler ensures the task is
                       when there is free            time
Interleaving option                                          executed whenever there is
                       available. Contrast this      with
                                                             nothing urgent to be done.
                       auto-breaking     where         the
                       objective was to expedite.
                       Especially in long running tasks
                       interim milestone reached             MCF is used constructively to
                       feedback may be necessary to          adjudge       the   expected
MCF Option
                       re-adjust      expected     task      completion time for long
                       completion time. We call it a         running tasks.
                       mid-course feedback (MCF).
                       NSTZ is an acronym for non-
                       scheduling time zones. Periods
                       when the scheduling engine will
                       not schedule (allot) a fresh task.
                                                             Scheduling     engine     takes
                       However, an already running
                                                             appropriate decision to cut into
                       task can either by design (or
                                                             NSTZ whenever necessary.
NSTZ cut-in option     because it is delayed) cut-into
                                                             Working during NSTZ is an
                       an impending NSTZ. System
                                                             additional cost and calculated
                       supports five categories of NSTZ
                                                             accordingly.
                       with varying importance and
                       user can define how much a
                       particular task can actually cut
                       into each of them.




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Execution preference               What it means                  Scheduling engine usage
                                It is possible for user to specify
                                that in an order if some task A
                                is executed on a particular work
                                center then preferably task B
                                too should be the next one           You can guess concept of
                                followed by task C and so on.        cascading is different from
                                Valid     reason     could     be    controlling    task    execution
                                substantial saving in cost and       order. The former is applicable
      Task line-up
                                time if done so. We call it task     within an order whereas the
                                cascading. This again could be       later could be across orders and
                                a preferential cascading or a        typically is a run-time user
                                forced cascading when user           intervention.
                                insists that the scheduling
                                engine waits a pre-determined
                                period for the next cascaded
                                task to mature for execution.

In addition to above user specified execution             up unless filled-up to some predefined minimum
preferences, the scheduling engine takes into             capacity.
consideration several other aspects as well and
does its own run-time adjustments as listed               6.3 Considering time for material movement
below.                                                    and normalization

6.1 Work center capacity                                  In real facilities it takes a while for work-in-
                                                          progress to be moved from the place it is
Checking if it is possible for a given task to be         created to where it is needed for further value-
executed on a work center must be done before             addition. This time too must be taken into
each allotment. Our system allows user to                 account before deciding fresh allotment. Both
define multi-part work centers that could either          fixed and variable types of material movement
work as a whole or in parts enabling one to               are considered and require separate notification
execute a variety of tasks each requiring it own          from a special console called Material
part capacity profile.                                    Movement Console (MMC) given to the person
                                                          responsible for material movement.
6.2 Activating work center
                                                          Additionally, certain WIP may require time to
Resources and work centers are conventionally             set, dry, solidify, etc. We call it time to
thought as synonyms, but in our system a                  normalize the WIP produced before further
resource has a very special meaning: a work               value-addition on it can begin.
center to become active requires resources.
What resources are required to activate a work            6.4 Deciding need for expediting or skipping
center is user defined. Therefore, if a work              task allotment
center is currently not active it is necessary to
check for resource availability. Task allotment           Breaking a task over more than one work
can only happen if it is possible to activate a           centers for concurrent execution is only
work center. This check is done automatically             advantageous if the task in question has reached
by the scheduling engine.                                 a critical stage. In our language, has sufficiently
                                                          exhausted the available leeway. Scheduler
Activating work centers could also be dependent           reckons how much the current leeway available
on capacity usage. A typical case could be an             is before taking such decisions. Likewise, if
industrial oven that is uneconomical to be fired-         sufficient leeway is available and if the user
                                                          desires task allotment may be skipped allowing


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other urgent tasks to be handled in the                while raising an alarm for human intervention to
meanwhile.                                             amend order workflow.

Further, if sufficient time is not available to        6.9 Monitor completion is within committed
complete a task as one has an impending NSTZ           date
or locked task then the scheduling engine could
either span the task, if possible, or decide to skip   Generally one must keep some safety buffer
allotment until later.                                 between when actually an order will be
                                                       completed and the date of delivery committed
6.5 Deselecting inappropriate work center              to the customer. On each reschedule, expected
                                                       completion time for all orders are re-calculated.
At run-time work centers that were originally          However, if for some reason order completion
thought appropriate to execute a task may              crosses the cut-off date an alarm is raised by the
become inappropriate as they waste more than           scheduling engine.
the reported good count of inputs actually
available now. Similarly, in a multi-plant facility    6.10 Monitoring task execution          (duration,
if certain WIP is created in one plant and the              wastage, cost etc.)
next value-adding work center too is available in
the same plant but not currently free then the         Expected duration, cost, wastage, time for the
scheduling engine may decide to wait for it to         output from a task to become usable for
become free rather than send WIP to another            subsequent value-addition (normalization time)
plant’s work center if doing so is advantageous.       and capacity the task may partake of each work
                                                       center it can be executed on, are all calculated
6.6 Deciding to hasten-up task execution               during job definition stage itself in the JSW.
                                                       User can define complex formulae and lookup
No matter how complex a rule one may use to            tables using attribute values specific to each
anticipate task’s total duration it is still an        task to arrive at these figures. However, the
estimate. When situation demands one may               scheduling engine also captures the actual
slightly expedite task execution to finish it faster   values in each case. Doing so not only allows
than expected. It is a done thing in practice and      one to control deviation task-wise at run-time
the scheduling engine too, if necessary, does the      but enables periodic revision of estimation rules
same, of course within user permitted limits.          in order to match them to reality as closely as
                                                       possible.
6.7 Decision to re-purpose inputs
                                                       For example, if any task actual execution time
Identical inputs could be processed by different       exceeds its estimated duration it turn black on
tasks to produce something different.                  the live Gantt chart allowing concerned
Assignment of specific task inputs is rather           supervisors to only focus on late tasks. Several
notional and one can, if need be, re-purpose           useful reports too can be generated highlighting
inputs to expedite those tasks whose other             exceptions. Actual vis-à-vis estimated data can
inputs are deemed available. Human schedulers          also be used to tailor a micro-level incentive
often take such decisions and so does the              scheme as resource capacity is translated in
scheduling engine provided user allows (or             time terms and thus easier to assess and
defines) such a swapping as possible.                  monitor.

6.8 Decision to freeze part or whole order             6.11 Procurement and maintenance too are
                                                       considered tasks
In case of any reported shortfall in WIP count for
any reason it makes sense to temporarily halt          We consider procurement of customer inputs
order execution, make good the shortfall and           and raw material too as tasks performed by
then resume executing order again. Humans do           customer interaction personnel or buyers. Any
take such decisions and so does the scheduling         deviation in expected arrivals of inputs has a
engine. It decides to suspend order execution          bearing on the overall schedule. Likewise,

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maintenance activities also keep the work             7 Vital statistics from the first successful
centers busy and affect the schedule and thus         installation
are treated as tasks.
                                                      The entire system is now mature and rigorously
6.12 Actual task execution may not always be          tested to exacting conditions in its first full-
successful                                            fledged installation at a medium sized
                                                      commercial print setup in India. It has been
Every allotted task may not be completed              working for more than 3 years now giving us the
successfully. We have the following options           confidence to make it available for the benefit
available with the Operator for an allotted task.     of the world at large.
Operator can roll back an allotted task with a
request to reassign it later. In case, Operator       The system is user configurable and starts by
has already started working on the task it could      defining the manufacturing facility in detail.
still be re-allotted: a way of telling the            They include identifying:
scheduling engine that it is not possible to
complete the task now though it can be                7.1 Work centers
completed later by me or by someone else.
Operators’ can pause and resume working on a          Listing of individual work centers of the factory,
task. In the worst case, Operators’ can also          classified by departments, and if a multi-plant
declare a task as terminated meaning it is no         (location) facility, then by plants.        The first
more possible to complete the task as inputs are      installation is a multi-plant facility. Table-2 gives
either damaged or destroyed - an error                details of the work centers and their
condition requiring human intervention to make        distribution.
good the shortfall. All the above impact the
schedule and are considered by the scheduling         Table-2: First installation work center details
engine.                                                   Number of individual work
                                                                                                 419
                                                          center
Then there are several more activities
performed by the scheduling engine like –                 Number of departments                   47

•   Reassessing what is completed until now               Number of plants / locations             5
•   How much more time existing tasks would
    require
                                                      7.2 Tasks and what they produce
•   The actual time, wastages and costs
    (including overtime cost) incurred until now
                                                      Tasks get executed on work centers. Tasks
    and so on.
                                                      produces        some      things recognized   as
                                                      “component” and may also require some things
It is very easy to guess, a lot of thinking happens
                                                      to add value to, again a “component”. The tasks
to ensure that each allotted task can indeed be
                                                      and the components it produces actually make
executed on the shop floor and every
                                                      up the CT diagram. User must define what
eventuality, even after task allotment, is taken
                                                      elemental value-adding tasks can be performed
cognizance of.       Technically the scheduling
                                                      in the facility and what generic components
engine can run autonomously with inbuilt
                                                      they produce. They are but few in type - what
capability to raise an alarm for human
                                                      changes from order-to-order is are the
intervention only when situation so warrants – a
                                                      attributes of generic tasks and components like,
precondition for realizing a true computer
                                                      extent to be value-added, cost, wastage,
controlled manufacturing facility.
                                                      duration, etc. Table-3 details the number of
                                                      generic tasks and components defined in the
                                                      first typical installation.




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Table-3: First installation task & component             scenario, if time to reschedule exceeds 60
details                                                  seconds the system automatically, for such
      Number of generic tasks          27                instances, chooses to skip a reschedule to align
                                                         with the next minute.
      Number of generic
                                       71
      components
                                                         8 Conclusion
                                            th
Actual system performance as on 19               April   Talika PMS is in its infancy. It is just born. Not
2013.                                                    many are even aware that such an inexpensive,
                                                         easy to use, self-configurable, off-the-shelf
History: The first installation is in its fourth         product exist that holds the promise of
successful year with the average mean time               positioning any manufacturing facility leagues
between system failure now exceeding 6                   apart from its competitors in terms of cost of
months, which in the beginning was around 6              production and reliability of service offered. It is
minutes. That shows how reliable the system              just a matter of time before someone makes a
now is.                                                  beginning forcing others to adopt similar
                                                         systems just to remain in business.
Each time a job is scheduled it is given a running
serial number. It started from ‘1’ and now reads         You can know more about Talika PMS by
30900. With 706 currently active jobs, it means          visiting www.etalika.in and also download a
30194 jobs were successfully executed by or via          free full demo version for evaluation.
the system with each job having about 70
elemental tasks on an average.

How fast it works: The scheduling Engine works
on Dell T310 Power edge server. It has 706
currently active jobs with 49466 elemental tasks
to schedule individually with all the complexity
of decision making already described. Table-4
gives an actual peek of the speed at which the
system works on this date.

Table-4: First installation Scheduling Engine load
    Number of active jobs                706
    Number elemental tasks to
                                       49466
    reckon with
    Time to decide what to do
                                            4
    NOW (seconds)
    Time to reschedule: predict
    micro-level future schedule          25
    completely (seconds)

Scheduling engine work at a phenomenal speed
of about 1900 tasks / second when it
reschedules, that happens once every minute
making the system live. You can guess the
decision to allot tasks now and knowing effect of
all current decisions as schedule prediction are
independent processes. Time to reschedule is
decided by the number of elemental tasks
present and varies linearly.      In worst case


                                                                                                 Page 11 of 13
                                                                                     © 2013, Laxman C Marathe
Exhibit–1: Console Functionality in brief
       Console                              Function                          Number & Location
                           Define and estimate all aspects of an      JSW is a multi-use console. Sales
                           orders;                                    persons,      Customer     Support
Job Study Wizard           Simulate or schedule orders;               personnel, shop floor Managers
(JSW)                      Monitor order progress;                    and    Supervisors     and     even
                           Manage / Change order execution;           customers all can have one for their
                           CRM functionality.                         personal use.
                           It is the Operators’ console. Details of
                           all allotted tasks flow in real-time to
                                                                      One WCC can represent one or
                           these consoles for Operators’ to notify
                                                                      several or all work center in a
                           task progress milestones.
Work Center Console                                                   facility.  Users can tailor the
                           Also gives details of all tasks already
(WCC)                                                                 number of WCCs required to cover
                           done and those lined up for execution
                                                                      all work centers on the shop floor.
                           later.
                                                                      System puts no higher limit.
                           Valuable machine statistics and many
                           more helpful features.
                           Any inputs required from customers?
Customer Interaction                                                  As many as personnel involved in
                           Track, follow-up and notify input when
Console (CIC)                                                         managing customer inputs.
                           they arrive in order of requirement
                           Preventive Maintenance as well as
                           unexpected breakdowns engage work
                           centers and affect the schedule. One
                           can define preventive maintenance
Maintenance Console        schedule in advance and treat it like a
                                                                      As many as required.
(MTN)                      maintenance job that can be scheduled
                           like any other order. This console helps
                           define a preventive maintenance
                           program, schedule it and notify its
                           activities.
                           Movement and storage of work-in-
                           progress is a critical function in the
                           value-adding process and affects the
Material Movement
                           schedule. We designed a console for        As many as required.
Console (MMC)
                           the person in charge of work-in-progress
                           that performs all functions as required
                           in real-time.
                           Orders may require raw material either
                           sourced from stores or purchased.
                           Need for material is decided and driven
Inventory                  by the scheduling core and thus an
Management                 entire material management system is       As many as required.
Consoles (IMCs)            created around the scheduling core.
                           This one console takes different avatars
                           depending on what specific inventory
                           functionality is required.




                                                                                               Page 12 of 13
                                                                                   © 2013, Laxman C Marathe
Console                               Function                               Number & Location
                            System is fully user configurable and all
                            this information resides in one logical
                            database called the factory dB.
                            However, user must have a means to
Factory dB Manager          modify the factory dB without affecting
                                                                            As many as required.
(FDM)                       current working system. FDM allows
                            one to check-out locally a copy of the
                            factory dB for manipulation / change,
                            revalidate it and check-in the factory dB
                            when finalized.
                            All monetary information generated by
                            the scheduling core is fetched
Money Management            periodically by this console for financial      As many as required. Only in
Console (MMM)               accounting purposes. One can then               concept stage.
                            build or dove tail this information into
                            any existing financial ERP system.
                            Manpower information like past usage,
                            current manning information being used
                            and future requirements too flow from
Human Resource                                                              As many as required. Only in
                            the scheduling core. This console is
Consoles (HRC)                                                              concept stage.
                            designed to cull out or control such
                            information or feed it into any existing
                            ERP system.



References

[1] D. Ouelhadj, S. Petrovic - A survey of dynamic scheduling in manufacturing systems - Springer Science:
Journal Scheduling (2009) 12: 417–431 - Published online: 28 October 2008

[2] Cowling, P.; Johansson, M. - Production, Manufacturing and Logistics
Using real time information for effective dynamic scheduling - Elsevier: European Journal of Operational
Research 139 (2002) 230–244

[3] Guilherme, E.V.; Herrmann, J.W.; Lin, E. - Rescheduling Manufacturing Systems: A framework of
strategies, policies and methods - Journal of scheduling, Kluwer Academic Publishers, Netherlands

[4] Velaga P., Ph.D. (Scheduling) President, Optisol, 3910 Stony Creek Ln, College Station, Texas 77845 -
Advantages & Difficulties with Drag-and-Drop Operations – Web page link: http://www.optisol.biz/Drag-
and-Drop.htm

[5] Zhang L., Li, X., Gao, L., Yang, Y., Jiang , P. - Predictive/reactive scheduling with uncertain disruptions -
proceedings of the 41st international Conference on Computers & Industrial Engineering P 260-265




                                                                                                       Page 13 of 13
                                                                                           © 2013, Laxman C Marathe

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Production planning and scheduling

  • 1. An Innovative Real Time Production Management System A white paper Abstract Scheduling is indeed a major issue in all manufacturing and project execution facilities world over. It is also recognized that if scheduling is efficient and automated huge benefits could result as existing resource usage can be maximized allowing dramatic increase in number of orders processed at the same time substantially reducing cost of production while ensuring reliability in delivery on the committed date. No wonder scheduling is a hot research topic and the market is flooded with scheduling systems of sorts. Still a truly efficient and automatic scheduling system remains an elusive dream. This white paper lists the six important reasons why a scheduling system fails in real-life situations. It then describes how a new scheduling system called Talika PMS satisfies all the six critical requirements in detail with real data supporting the claims from its first major installation. Visit www.etalika.in for more information and free download 1 Introduction Before we elucidate more on the system features we would like to re-emphasis importance of scheduling Day-to-day scheduling of any manufacturing facility in any manufacturing facility and why current is recognized to be the most important problem to solutions fail to address the problem correctly. be solved. [1] D. Ouelhadj and S. Petrovic recent [Oct 2008] study reveals that solutions based on 2 Importance of scheduling creation of a static schedule are impractical in real- life situations and discusses several dynamic The only real differentiators to compete in scheduling approaches only to conclude that more established products and services market are Cost work is still needed in this field of research. and Reliable delivery. Quality of product / service is mostly considered a pre-condition to be in business We wish to present here a complete dynamic real- rather than a differentiator. Both cost and reliable time micro level scheduling system that is proven to delivery of product / service are directly impacted by work in the most complex manufacturing facilities. It scheduling. is a fully scalable, decentralized, multi-location and user configurable system to suit any manufacturing / 2.1 Scheduling and cost of production project environment. The core scheduling is fully automatic and guarantees that all currently allotted It is almost axiomatic to state that a major portion of tasks in real-time can be executed with a complete cost of production (even exceeding 70% - 80% in and detailed schedule prediction of all activities for made-to-order industries) is expended in all orders in-hand. The system automatically coordinating and managing production activities vis- reschedules in response to real-time events as à-vis the actual cost of value-addition involved. notified by operators’ handling current tasks on the shop floor, with an objective to maximize resource Most real life manufacturing involves execution of utilization while minimizing job cycle time. It offers several individual activities in a complex order to full micro-level future schedule visibility of all create any saleable final product or service. The running jobs to predict when each would be over starting point thus is in breaking down an order given the current load as of NOW. The cycle of requirement into elemental activities that must be allotting tasks, seeking task-wise feedback on completed in order to accomplish the final product / allotments made from operators’ on shop floor, and service deliverable: ranging from getting inputs or re-predicting its impact in subsequent reschedule raw material until final packing and dispatch. Unless happen every minute 24x7. this detailing is not done, actual value addition cannot begin. Once it is known “How” the order can be fulfilled the most difficult job of scheduling Page 1 of 13 © 2013, Laxman C Marathe
  • 2. individual activities of orders begin. It primarily seldom match reality owing to unexpected translates in deciding what activity must be done, disruptions [3] & [5]. where it should be done (that is using what limited resources) and when. One can refer to them as the So, any scheduling system that fails to respond to 3W’s. Most expensive and competent personnel in changing situation on ground by failing to reschedule any manufacturing or project execution facility are and redraw its prediction (Gantt chart) is a misfit in engaged fully in the process of managing production real life making purported schedule optimality and that involves, breaking down order execution, efficiency claims hypothetical. estimating its cost, time and wastages, deciding what activities to do now and next, taking feedback 3.2 No feedback mechanism on progress made, follow-up and expediting to meet deadlines. The whole exercise is repeated all over A scheduling system can only be responsive to what again by rescheduling to predict and monitor is happening on the shop floor if a feedback expected completion dates for all orders in hand. mechanism exists. This feedback mechanism should be both real-time and automatic. Peter Cowling and Add to this already complex situation, the burden of Marcus Johansson [2] argue in a well researched estimating when new orders can be delivered given paper that “in many production processes real time the existing load of orders already in-hand. All this is information may be obtained from process control now possible to be completely automated resulting computers and other monitoring systems, but most in a substantial reduction in the cost of production. existing scheduling models are unable to use this information to effectively influence scheduling 2.2 Scheduling & reliability decisions in real time”. This is a major disconnect making the schedule infeasible as it is soon out of Scheduling decisions taken now directly impact synchronization with reality. expected completion times of all orders in-hand. In real-life situations one has to deal with several We have recognized that the only authentic real- orders, each with its own set of individual time source of feedback information from the shop interdependent activities requiring a certain profile floor is the personnel (Operators’) in charge of of resources that are both shared and limited. It is performing individual activities. However, each well impossible, even in small setups, to manually operator can only give feedback on what each one figure-out impact of real-time decisions on predicted does and that too ideally limited to the current task completion dates. in-hand. We achieve a seamless feedback mechanism to the scheduling engine by allocating Honoring delivery on committed date is more elemental executable tasks in real-time to individual important than how fast one turns around an order Operators, and seeking task-specific feedback for in a manufacturing facility. It is only possible to do each such allotted task. The process of task so, if one is in a position to predict impact of all allotment, progress feedback and subsequent scheduling decisions taken now on all orders in-hand reschedule to decide what to do next happens 24x7 in real time as an on-going process. automatically. 3 Why conventional scheduling systems fail in the 3.3 Schedule not actionable real world? The decision to execute an elemental task or activity 3.1 Static scheduling of an order requires one to take into account several aspects; availability of inputs, availability of Scheduling is a widely misunderstood term. Many resources and technical feasibility of performing the believe plotting activities to be performed on task. Most scheduling systems usually fail on this different resources on a time scale (Gantt chart) count. Proposed activities are either not actionable make a schedule. Actually a Gantt chart is just a or represent a group of activities leaving the decision snap shot of what is likely to happen in the future of what exactly to do now to the operators. In order given the situation NOW. As one progresses in time to circumvent this problem, many systems offer a this representation will change because predictions “drag & drop” facility to correct or manipulate proposed schedule before it is released. As [4] P. Page 2 of 13 © 2013, Laxman C Marathe
  • 3. Velaga asserts, presence of a “drag & drop” facility unaltered any amendment to future task listing in no indicate an inherent weakness of the scheduling way adds to nervousness. On the contrary, impact logic. on completion dates of all jobs in hand must be known immediately not when the next frozen 3.4 Manufacturing facilities are on-going concerns schedule is created. Getting new orders and completing existing orders is We propose a true scheduling system called Talika a continual process in real facilities. Existing Production Management System (PMS) that satisfies commitments cannot generally be disturbed because all the above primary requirements. of new orders. Situations can become more complex as orders could be cancelled or amended. Any 4 Overview of Talika PMS scheduling solution that considers a static order load is therefore impractical. The system has a distributed architecture as indicated in Figure-1. At the center is the real-time 3.5 Working in shifts scheduling engine working round-the-clock and is the live heart of the system. Several different types Many manufacturing facilities work round the clock of consoles interact with the scheduling engine using in shifts manned by a different set of personnel. a proprietary protocol that is robust and Scheduling decisions impact across shifts and the asynchronous making the entire process of biggest challenge becomes information handover communication absolutely safe. between shifts. The only remedy is in having the scheduling systems work 24x7 continuously. There are several different types of consoles each designed to perform a specific function on the shop 3.6 Stability versus responsiveness floor. Consoles work in a standalone mode but can also communicate with the scheduling engine, if Most scheduling systems provide a stable schedule connected, making the entire distributed system live frozen for a period (usually a few days) and expects and reliable. Exhibit–1 at the end details it to hold well unless disruptions occur, which functionality of each Console shown in Figure-1 and inevitably do occur. It is reasoned that having a explains how the automatic scheduling engine drives continually changing schedule results in shop floor other peripheral or support activities. Most ERP nervousness. Shop floor nervousness is a myth systems only handle the peripheral activities sans propagated to hide inability of doing a quick the driving scheduling engine at its heart, making it reschedule. Operators’ are only concerned with the more of a fancy carcass disconnected from the shop task in-hand. As long as the current task remains floor. Page 3 of 13 © 2013, Laxman C Marathe
  • 4. Figure-1: Macro system schema 5 How the system works One can also create part CT diagrams for common work flows in the factory and save Figure-2 gives an at-a-glance view of how the them as sub-assemblies. Sub-assemblies are entire system works. building blocks one may use to quickly create a new complex job definition. 5.1 Starting point Jobs are stored as proprietary files with a Job Study Wizard (JSW) is the starting point. As default “*.tlk” extension to any media. One can already explained each sales person or save, share and reuse stored jobs over and over concerned agency can have a JSW of their own. again just like a text file. Potential enquiries can be quickly converted to a detailed job definition depicted as an easy to 5.2 Scheduling a job understand component task (CT) diagram. CT diagram actually represents the micro level It is not necessary all defined jobs be actually activity work flow for creating one-something of scheduled. Jobs could be defined when we any value-added service or product. It is more receive an enquiry to estimate its cost and like a recipe. One can always scale it up or down assess delivery date, but we only need to to match extent of final output required keeping schedule the order when it matures. When the CT diagram (recipe) unchanged. It is also scheduled, orders flow over to the scheduling possible to create, as a one-time exercise, a engine and the process of executing its bank of most standard CT diagrams (standard constituent tasks begin. orders) used in the facility. So, defining new orders may simply translate into picking up an 5.3 Role of scheduling engine and shop floor appropriate or nearly matching already defined interface: Work Center Console (WCC) CT diagram and making minor adjustments to it. Scheduling engine works 24x7 and proactively controls all factory work centers at a micro level. Page 4 of 13 © 2013, Laxman C Marathe
  • 5. It decides what tasks of which orders can and to the scheduling engine to be taken cognizance should be actually allotted for execution to the of during the next reschedule that happens shop floor. Complete information of currently every minute. This cycle of allotting tasks, allotted tasks flows to the concerned WCC in getting progress and completion notification real-time. Operators’ acknowledge allotted feedback, and subsequent fresh allotment on tasks to start execution and notify interim each work center on the shop floor goes on milestones achieved, until the allotted task is without end. not over. All notifications flow back in real-time Figure-2: Working principle at-a-glance 6 Working logic of scheduling engine Scheduling engine comprises of a set of complex the JSW itself. Only on confirmation, valid daemons working round-the-clock. Like a orders are communicated to the scheduling human scheduler does, it always decides what engine. During order definition stage itself a lot tasks to execute now. The entire optimization of detailing about the job is done including de- principle could be summed in one line as “if selection of technically non-feasible work something (read a task) can be done and it centers to execute specific tasks of the job. should be done then it will be done”. The above User can also specify several guidelines for the rule automatically guarantees that resource scheduling engine to follow while executing the utilization is maximized while simultaneously order called “execution preferences”. reducing job cycle time. Scheduling engine uses its own intelligence while implementing user specified guidelines An order is first broken-down to its elemental but ensures they are honored whenever tasks in form of a CT diagram during definition in possible. Execution preferences are not rigid; Page 5 of 13 © 2013, Laxman C Marathe
  • 6. they can be changed even at run-time after a all tasks in an order. Table-1 below lists the job is scheduled. Execution preferences could execution preferences and explains what each be different for each task. However, user can means and how the scheduling engine uses specify them just once with applicability them while making allotment decisions. controlled across parts or group of tasks or for Table-1: Execution Preferences and what they mean Execution preference What it means Scheduling engine usage If WIP is not on the critical Attempt to minimize work-in- chain and has enough time left progress (WIP) from being to be produced and used then WIP control created too much in advance its creation is deferred thereby and thus remain unused. minimizing WIP build-up on the shop floor. Tasks are allotted first by order priority and then by the future User desires to change task Control of task burden on the task within an execution order, if necessary, at execution order order. However, user may run-time. change this natural order of execution at run time. Scheduler tries to honors user preference with switchover savings, if any, considered. In If one has a choice of work case the first preferred work Work center choice centers to perform a task then center is unavailable it tries to which one to choose? allot the task on the second preferred work center and so on. Ensuring a particular task is Always tries to execute the said Locking Option only executed within a user task within the specified period, specified period. as far as possible. If the task is on the critical chain Breaking up a task to run or its execution cannot be concurrently on more than one deferred any further scheduling Auto-breaking option work center with an intention engine will try to optimize and to reduce task execution time. select the most appropriate breaking option possible. Stop and resume task execution after a holiday, recess period. Scheduler wisely decides to Spanning Option Commonly referred to as a non- span or not to span depending scheduling time zone (NSTZ) in on the current situation. the system. Page 6 of 13 © 2013, Laxman C Marathe
  • 7. Execution preference What it means Scheduling engine usage It may not be necessary to wait to start the next value-adding Scheduler tries to begin the task that uses or consumes next value adding task even what is produced by the current before the earlier one feeding task until the current task is not into the next one is not yet MCI option over. One can overlap in time over. Time to initiate the next both tasks in order to expedite task can be user decided or left the order. We can say the to the scheduling engine to preceding task gives a mid- figure out. course intimation (MCI) to the next task to begin. User may want some tasks (orders) to be executed only Scheduler ensures the task is when there is free time Interleaving option executed whenever there is available. Contrast this with nothing urgent to be done. auto-breaking where the objective was to expedite. Especially in long running tasks interim milestone reached MCF is used constructively to feedback may be necessary to adjudge the expected MCF Option re-adjust expected task completion time for long completion time. We call it a running tasks. mid-course feedback (MCF). NSTZ is an acronym for non- scheduling time zones. Periods when the scheduling engine will not schedule (allot) a fresh task. Scheduling engine takes However, an already running appropriate decision to cut into task can either by design (or NSTZ whenever necessary. NSTZ cut-in option because it is delayed) cut-into Working during NSTZ is an an impending NSTZ. System additional cost and calculated supports five categories of NSTZ accordingly. with varying importance and user can define how much a particular task can actually cut into each of them. Page 7 of 13 © 2013, Laxman C Marathe
  • 8. Execution preference What it means Scheduling engine usage It is possible for user to specify that in an order if some task A is executed on a particular work center then preferably task B too should be the next one You can guess concept of followed by task C and so on. cascading is different from Valid reason could be controlling task execution substantial saving in cost and order. The former is applicable Task line-up time if done so. We call it task within an order whereas the cascading. This again could be later could be across orders and a preferential cascading or a typically is a run-time user forced cascading when user intervention. insists that the scheduling engine waits a pre-determined period for the next cascaded task to mature for execution. In addition to above user specified execution up unless filled-up to some predefined minimum preferences, the scheduling engine takes into capacity. consideration several other aspects as well and does its own run-time adjustments as listed 6.3 Considering time for material movement below. and normalization 6.1 Work center capacity In real facilities it takes a while for work-in- progress to be moved from the place it is Checking if it is possible for a given task to be created to where it is needed for further value- executed on a work center must be done before addition. This time too must be taken into each allotment. Our system allows user to account before deciding fresh allotment. Both define multi-part work centers that could either fixed and variable types of material movement work as a whole or in parts enabling one to are considered and require separate notification execute a variety of tasks each requiring it own from a special console called Material part capacity profile. Movement Console (MMC) given to the person responsible for material movement. 6.2 Activating work center Additionally, certain WIP may require time to Resources and work centers are conventionally set, dry, solidify, etc. We call it time to thought as synonyms, but in our system a normalize the WIP produced before further resource has a very special meaning: a work value-addition on it can begin. center to become active requires resources. What resources are required to activate a work 6.4 Deciding need for expediting or skipping center is user defined. Therefore, if a work task allotment center is currently not active it is necessary to check for resource availability. Task allotment Breaking a task over more than one work can only happen if it is possible to activate a centers for concurrent execution is only work center. This check is done automatically advantageous if the task in question has reached by the scheduling engine. a critical stage. In our language, has sufficiently exhausted the available leeway. Scheduler Activating work centers could also be dependent reckons how much the current leeway available on capacity usage. A typical case could be an is before taking such decisions. Likewise, if industrial oven that is uneconomical to be fired- sufficient leeway is available and if the user desires task allotment may be skipped allowing Page 8 of 13 © 2013, Laxman C Marathe
  • 9. other urgent tasks to be handled in the while raising an alarm for human intervention to meanwhile. amend order workflow. Further, if sufficient time is not available to 6.9 Monitor completion is within committed complete a task as one has an impending NSTZ date or locked task then the scheduling engine could either span the task, if possible, or decide to skip Generally one must keep some safety buffer allotment until later. between when actually an order will be completed and the date of delivery committed 6.5 Deselecting inappropriate work center to the customer. On each reschedule, expected completion time for all orders are re-calculated. At run-time work centers that were originally However, if for some reason order completion thought appropriate to execute a task may crosses the cut-off date an alarm is raised by the become inappropriate as they waste more than scheduling engine. the reported good count of inputs actually available now. Similarly, in a multi-plant facility 6.10 Monitoring task execution (duration, if certain WIP is created in one plant and the wastage, cost etc.) next value-adding work center too is available in the same plant but not currently free then the Expected duration, cost, wastage, time for the scheduling engine may decide to wait for it to output from a task to become usable for become free rather than send WIP to another subsequent value-addition (normalization time) plant’s work center if doing so is advantageous. and capacity the task may partake of each work center it can be executed on, are all calculated 6.6 Deciding to hasten-up task execution during job definition stage itself in the JSW. User can define complex formulae and lookup No matter how complex a rule one may use to tables using attribute values specific to each anticipate task’s total duration it is still an task to arrive at these figures. However, the estimate. When situation demands one may scheduling engine also captures the actual slightly expedite task execution to finish it faster values in each case. Doing so not only allows than expected. It is a done thing in practice and one to control deviation task-wise at run-time the scheduling engine too, if necessary, does the but enables periodic revision of estimation rules same, of course within user permitted limits. in order to match them to reality as closely as possible. 6.7 Decision to re-purpose inputs For example, if any task actual execution time Identical inputs could be processed by different exceeds its estimated duration it turn black on tasks to produce something different. the live Gantt chart allowing concerned Assignment of specific task inputs is rather supervisors to only focus on late tasks. Several notional and one can, if need be, re-purpose useful reports too can be generated highlighting inputs to expedite those tasks whose other exceptions. Actual vis-à-vis estimated data can inputs are deemed available. Human schedulers also be used to tailor a micro-level incentive often take such decisions and so does the scheme as resource capacity is translated in scheduling engine provided user allows (or time terms and thus easier to assess and defines) such a swapping as possible. monitor. 6.8 Decision to freeze part or whole order 6.11 Procurement and maintenance too are considered tasks In case of any reported shortfall in WIP count for any reason it makes sense to temporarily halt We consider procurement of customer inputs order execution, make good the shortfall and and raw material too as tasks performed by then resume executing order again. Humans do customer interaction personnel or buyers. Any take such decisions and so does the scheduling deviation in expected arrivals of inputs has a engine. It decides to suspend order execution bearing on the overall schedule. Likewise, Page 9 of 13 © 2013, Laxman C Marathe
  • 10. maintenance activities also keep the work 7 Vital statistics from the first successful centers busy and affect the schedule and thus installation are treated as tasks. The entire system is now mature and rigorously 6.12 Actual task execution may not always be tested to exacting conditions in its first full- successful fledged installation at a medium sized commercial print setup in India. It has been Every allotted task may not be completed working for more than 3 years now giving us the successfully. We have the following options confidence to make it available for the benefit available with the Operator for an allotted task. of the world at large. Operator can roll back an allotted task with a request to reassign it later. In case, Operator The system is user configurable and starts by has already started working on the task it could defining the manufacturing facility in detail. still be re-allotted: a way of telling the They include identifying: scheduling engine that it is not possible to complete the task now though it can be 7.1 Work centers completed later by me or by someone else. Operators’ can pause and resume working on a Listing of individual work centers of the factory, task. In the worst case, Operators’ can also classified by departments, and if a multi-plant declare a task as terminated meaning it is no (location) facility, then by plants. The first more possible to complete the task as inputs are installation is a multi-plant facility. Table-2 gives either damaged or destroyed - an error details of the work centers and their condition requiring human intervention to make distribution. good the shortfall. All the above impact the schedule and are considered by the scheduling Table-2: First installation work center details engine. Number of individual work 419 center Then there are several more activities performed by the scheduling engine like – Number of departments 47 • Reassessing what is completed until now Number of plants / locations 5 • How much more time existing tasks would require 7.2 Tasks and what they produce • The actual time, wastages and costs (including overtime cost) incurred until now Tasks get executed on work centers. Tasks and so on. produces some things recognized as “component” and may also require some things It is very easy to guess, a lot of thinking happens to add value to, again a “component”. The tasks to ensure that each allotted task can indeed be and the components it produces actually make executed on the shop floor and every up the CT diagram. User must define what eventuality, even after task allotment, is taken elemental value-adding tasks can be performed cognizance of. Technically the scheduling in the facility and what generic components engine can run autonomously with inbuilt they produce. They are but few in type - what capability to raise an alarm for human changes from order-to-order is are the intervention only when situation so warrants – a attributes of generic tasks and components like, precondition for realizing a true computer extent to be value-added, cost, wastage, controlled manufacturing facility. duration, etc. Table-3 details the number of generic tasks and components defined in the first typical installation. Page 10 of 13 © 2013, Laxman C Marathe
  • 11. Table-3: First installation task & component scenario, if time to reschedule exceeds 60 details seconds the system automatically, for such Number of generic tasks 27 instances, chooses to skip a reschedule to align with the next minute. Number of generic 71 components 8 Conclusion th Actual system performance as on 19 April Talika PMS is in its infancy. It is just born. Not 2013. many are even aware that such an inexpensive, easy to use, self-configurable, off-the-shelf History: The first installation is in its fourth product exist that holds the promise of successful year with the average mean time positioning any manufacturing facility leagues between system failure now exceeding 6 apart from its competitors in terms of cost of months, which in the beginning was around 6 production and reliability of service offered. It is minutes. That shows how reliable the system just a matter of time before someone makes a now is. beginning forcing others to adopt similar systems just to remain in business. Each time a job is scheduled it is given a running serial number. It started from ‘1’ and now reads You can know more about Talika PMS by 30900. With 706 currently active jobs, it means visiting www.etalika.in and also download a 30194 jobs were successfully executed by or via free full demo version for evaluation. the system with each job having about 70 elemental tasks on an average. How fast it works: The scheduling Engine works on Dell T310 Power edge server. It has 706 currently active jobs with 49466 elemental tasks to schedule individually with all the complexity of decision making already described. Table-4 gives an actual peek of the speed at which the system works on this date. Table-4: First installation Scheduling Engine load Number of active jobs 706 Number elemental tasks to 49466 reckon with Time to decide what to do 4 NOW (seconds) Time to reschedule: predict micro-level future schedule 25 completely (seconds) Scheduling engine work at a phenomenal speed of about 1900 tasks / second when it reschedules, that happens once every minute making the system live. You can guess the decision to allot tasks now and knowing effect of all current decisions as schedule prediction are independent processes. Time to reschedule is decided by the number of elemental tasks present and varies linearly. In worst case Page 11 of 13 © 2013, Laxman C Marathe
  • 12. Exhibit–1: Console Functionality in brief Console Function Number & Location Define and estimate all aspects of an JSW is a multi-use console. Sales orders; persons, Customer Support Job Study Wizard Simulate or schedule orders; personnel, shop floor Managers (JSW) Monitor order progress; and Supervisors and even Manage / Change order execution; customers all can have one for their CRM functionality. personal use. It is the Operators’ console. Details of all allotted tasks flow in real-time to One WCC can represent one or these consoles for Operators’ to notify several or all work center in a task progress milestones. Work Center Console facility. Users can tailor the Also gives details of all tasks already (WCC) number of WCCs required to cover done and those lined up for execution all work centers on the shop floor. later. System puts no higher limit. Valuable machine statistics and many more helpful features. Any inputs required from customers? Customer Interaction As many as personnel involved in Track, follow-up and notify input when Console (CIC) managing customer inputs. they arrive in order of requirement Preventive Maintenance as well as unexpected breakdowns engage work centers and affect the schedule. One can define preventive maintenance Maintenance Console schedule in advance and treat it like a As many as required. (MTN) maintenance job that can be scheduled like any other order. This console helps define a preventive maintenance program, schedule it and notify its activities. Movement and storage of work-in- progress is a critical function in the value-adding process and affects the Material Movement schedule. We designed a console for As many as required. Console (MMC) the person in charge of work-in-progress that performs all functions as required in real-time. Orders may require raw material either sourced from stores or purchased. Need for material is decided and driven Inventory by the scheduling core and thus an Management entire material management system is As many as required. Consoles (IMCs) created around the scheduling core. This one console takes different avatars depending on what specific inventory functionality is required. Page 12 of 13 © 2013, Laxman C Marathe
  • 13. Console Function Number & Location System is fully user configurable and all this information resides in one logical database called the factory dB. However, user must have a means to Factory dB Manager modify the factory dB without affecting As many as required. (FDM) current working system. FDM allows one to check-out locally a copy of the factory dB for manipulation / change, revalidate it and check-in the factory dB when finalized. All monetary information generated by the scheduling core is fetched Money Management periodically by this console for financial As many as required. Only in Console (MMM) accounting purposes. One can then concept stage. build or dove tail this information into any existing financial ERP system. Manpower information like past usage, current manning information being used and future requirements too flow from Human Resource As many as required. Only in the scheduling core. This console is Consoles (HRC) concept stage. designed to cull out or control such information or feed it into any existing ERP system. References [1] D. Ouelhadj, S. Petrovic - A survey of dynamic scheduling in manufacturing systems - Springer Science: Journal Scheduling (2009) 12: 417–431 - Published online: 28 October 2008 [2] Cowling, P.; Johansson, M. - Production, Manufacturing and Logistics Using real time information for effective dynamic scheduling - Elsevier: European Journal of Operational Research 139 (2002) 230–244 [3] Guilherme, E.V.; Herrmann, J.W.; Lin, E. - Rescheduling Manufacturing Systems: A framework of strategies, policies and methods - Journal of scheduling, Kluwer Academic Publishers, Netherlands [4] Velaga P., Ph.D. (Scheduling) President, Optisol, 3910 Stony Creek Ln, College Station, Texas 77845 - Advantages & Difficulties with Drag-and-Drop Operations – Web page link: http://www.optisol.biz/Drag- and-Drop.htm [5] Zhang L., Li, X., Gao, L., Yang, Y., Jiang , P. - Predictive/reactive scheduling with uncertain disruptions - proceedings of the 41st international Conference on Computers & Industrial Engineering P 260-265 Page 13 of 13 © 2013, Laxman C Marathe