Más contenido relacionado Similar a Basics of Pull_Manufacturing - A presentation.ppt (20) Basics of Pull_Manufacturing - A presentation.ppt1. 1
© 2004 Superfactory™. All Rights Reserved.
Pull Manufacturing
Kanban, Just in Time, Demand Flow
Superfactory Excellence Program™
www.superfactory.com
2. 2
© 2004 Superfactory™. All Rights Reserved.
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3. 3
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Outline
Why Pull Manufacturing?
The Problem of Inventory
Just In Time
Kanban
One Piece Flow
Demand / Pull
Standard Work & Takt Time
Production Smoothing
4. 4
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Why Pull Manufacturing?
Lean manufacturing is really about minimizing the
need for overhead
which is about concentrating precisely on only what
is necessary
which is about linking interdependent supply
system decisions, and actions
which needs to be visual, responsive and simple to
manage
5. 5
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Push Vs. Pull Scheduling
Push Scheduling
• traditional approach
• “move the job on when finished”
• problems - creates excessive inventory
Pull scheduling
• coordinated production
• driven by demand (pulled through system)
• extensive use of visual triggers
(production/withdrawal kanbans)
6. 6
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Inventory: Root of all evil
If the meaning of production control is truly understood,
inventory control is unnecessary.
-- Taiichi Ohno
7. 7
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Scrap
Work in process inventory level
(hides problems)
Unreliable
Vendors
Capacity
Imbalances
Inventory Hides Problems
8. 8
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Scrap
Unreliable
Vendors
Capacity
Imbalances
WIP
Lowering Inventory Reveals Problems
Accommodate lower inventory levels by:
•Reducing variability
•Eliminating waste
•Streamlining production and material flows
•Accurate information
9. 9
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Management philosophy of continuous and forced problem
solving (forced by driving inventory out of the production
system)
Supplies and components are ‘pulled’ through system to
arrive where they are needed when they are needed
What is Just-in-Time?
Goal: Achieve the minimal level of resources required to
add the necessary value in the production system.
10. 10
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Objective of JIT
To eliminate waste
by
Producing the needed item
at the right time
and the exact quantity
11. 11
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Objective of JIT
Produce only the products the customer wants
Produce products only at the rate that the customer
wants them
Produce with perfect quality
Produce with minimum lead time
Produce products with only those features the customer
wants
12. 12
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Objectives
Produce with no waste of labor, material or equipment --
every movement must have a purpose so that there is zero
idle inventory
Produce with methods that allow for the development of
people
13. 13
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JIT Principles
Create flow production
• one piece flow
• machines in order of processes
• small and inexpensive equipment
• U cell layout, counter clockwise
• multi-process handling workers
• easy moving/standing operations
• standard operations defined
14. 14
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JIT Principles
Establish “TAKT” time
• rate at which the customer buys a product
Build Pull Product
• use of kanban system
15. 15
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JIT Tactics
Single Minute Exchange of
Dies (SMED)
Statistical Process Control
Use of standard containers
Doable stable schedules with
adequate visibility
TAKT-Time
5-S Program
Kaizen Event
Visual control
Flexible workers
Tools at the point of need
Product redesign
Group Technology
Total Productive Maintenance
16. 16
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Suppliers
Total
Productive
Maintenance
Flexible
Layouts and
Processes
Small Lot
Production/
Short Setup
Demand/Pull
Scheduling
Quality
Flexible/
Empowered
Employees
JIT
Just-in-Time Success Factors
17. 17
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JIT Scheduling Tactics
Build products to stock or order
Plan level schedules (Constant rate of production)
Produce in small lots/mixed model production (dictated by
set-up and thru put times)
Demand initiates lower level production/supplier deliveries—
Use of kanbans
Suppliers plan to forecast/build to demand
18. 18
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Processes are easy to understand—visible
Quality issues are apparent immediately
Scope of problems are limited because of lower
inventory levels
TQM management methods are very important
Quality enables JIT
Quality of execution typically determines how
low inventories can be reduced!
19. 19
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Few
Nearby (if possible)
Repeat business/Longer Term Agreements
Analysis to enable desirable suppliers to become or stay
price competitive
JIT Logistics:
Frequent Deliveries/Smaller Quantities
Exact Quantities
Consumption initiates deliveries
Deliveries directly to the point of use
Perfect Parts
Concurrent engineering design practices
Characteristics of JIT Suppliers
20. 20
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Streamlined Production
Flow with JIT
Traditional Flow
Customers
Suppliers
Customers
Suppliers
Production Process
(stream of water)
Inventory (stagnant
ponds) Material
(water in
stream)
21. 21
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Waste Reduction (%)
82%
50%
50%
30%
30%
20%
40%
0% 20% 40% 60% 80% 100%
Work-in-Process
Raw Material
Lead Time
Space
Finished Goods
Scrap
Setup Time
JIT Reduced Waste at Hewlett-Packard
22. 22
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JIT production, AKA…
ZIPS (Zero Inventory Production System) -- Omark industries
MAN (Material As Needed) -- Harley Davidson (Also: “Quality Machine
Through Jelly-Beans,” where jelly beans refers to running one-piece
lots, or mixed models, in final motorcycle assembly)
MIPS (Minimum Inventory Production System) -- Westinghouse
Stockless Production -- Hewlett Packard, Greeley Div.
Continuous Flow Manufacturing (CFM) -- IBM
Kanban -- Many companies both in North America and Japan
Toyota System -- Many companies in Japan
Ohno System (after Taiichi Ohno, a Toyota vice president and master-
mind of the system) -- Many companies in Japan
Just-In-Time (JIT) Production -- Most popular term both in North
America and Japan
Lean Manufacturing -- The most recent term
23. 23
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JIT Logic in two simple formulas
Formula 1: Little’s Law
Formula 2: Average Production Lead Time
Average
Production Lead
Time
Throughput
Rate
Average
WIP
X
=
Measure of
System
Utilization
Average
Processing
Time
Average
Production
Lead Time
X
= X
C C
S A
2 2
Measure of variance in
the processing times of
jobs
Measure of variance of
interarrival times of
customer orders
24. 24
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Effects of JIT production
(F)
Heightened
awareness of
problems and
problem causes
(I)
Less indirect cost for:
interest on idle inventory,
space and equipment to
handle inventory, inventory
accounting, physical
inventory control
(H)
Reduced buffer
inventories and/or
workers
(E)
Fast feedback
on defects
(G)
Smoother
output rates
(D)
Less material
waste
(C)
Fewer rework
labor hours
(A)
Less
inventory
in the
system
(B)
Scrap/quality
control
Less material, labor, and indirect inputs for the same of higher output = higher productivity
Less inventory in the system = faster market response, better forecasting, and less administration.
Lot size
reductions
JIT
production
Deliberate
withdrawal of
buffer inventories
/ workers
Ideas for
cutting lot
sizes
Ideas for
improving
JIT delivery
performance
Ideas for
controlling
defects
25. 25
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How to accomplish JIT production
Concurrently
Solve Problems
-Root Cause
-Solve permanently
-Team approach
-Line and specialist
responsibiity
-Continual education
Measure Performance
-Emphasize
improvement
-Track trends
1) Design Flow Process
-Link operations
-Balance workstation
capacities
-Re-layout for flow
-Emphasize preventive
maintenance
-Reduce lot size
-Reduce setup/changeover time
7) Improve Product Design
-Standard product configuration
-Standardize and reduce
number of parts
-Process design with
product design
-Quality expectations
2) Total Quality Control
-Worker responsibility
-Measure: SQC
-Enforce compliance
-Fail-safe methods
-Automatic inspection
3) Stabilize Schedule
-Level schedule
-Underutilize capacity
-Establish freeze
windows
4) Kanban Pull
-Demand pull
-Backflush
-Reduce lot sizes
5) Work with Vendors
-Reduce lead times
-Frequent deliveries
-Project usage
requirements
-Quality expectations
6) Reduce Inventory More
-Look for other areas
-Stores
-Transit
-Carousels
-Conveyors
26. 26
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Limitations of JIT
Preconditions to JIT
• trust must be present
• labor/management
• suppliers/consumers
• recognition of processes
• familiarity with problem solving
• quality at the source
• agreement over value and waste
27. 27
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Limitations of JIT
Right Settings
• applicable in growth to maturity phases of
Product Life Cycle
• standard product
• Steinway and JIT
• standard/fixed pay-rate
• problems with piece-rate scheme
Universal agreement that change needed
28. 28
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Theoretical Benefits of JIT
Unpleasant surprises
eliminated
Less computerization
• visual control
Improved quality
WIP reduced
Better communications
Less pressure on receiving docks and
incoming inspection areas
Lower costs
Change in attitude
• Defects are treasures
29. 29
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Dealing with Variance
Four major stances:
• Buffer against it
• Ignore it
• Manage it
• Eliminate it
All forms of variance create cost
30. 30
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JIT & Variance
Variance a fact of life
Comes from many sources
• internal
scheduling changes, scheduling practices,
manufacturing planning & control systems,
absenteeism, process variability
• external
changes in forecasts, actual demand, customer
requested changes, government, competition, vendors
31. 31
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Japanese word for card
Authorizes production from downstream operations based
on physical consumption
May be a card, flag, verbal signal etc.
Used often with fixed-size containers
Kanban quantities are a function of lead-time and
consumption rate of the item being replenished (min
qty=(demand during lead-time + safety stock)/ container
quantity)
Kanban
32. 32
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Kanban Production Control Systems
A
B
Machine Center Assembly Line
Storage
Production
Kanban
Withdrawal
Kanban
....
34. 34
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Kanban Card
46-281247p1
27” Al Rim
Qty
23
Stock Loc:
RIP 1
Line Loc:
Asm. 1
Unique Part #
Description
Kanban Qty
Where to find
part when bin
is empty Where to return
filled Kanban
35. 35
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For JIT & Kanban to work, quality must be high
There can be no extra inventory to buffer against
the production or use of defective units
Producing poor-quality items, and reworking or rejecting
them is wasteful
The workers must be responsible for inspection &
production quality
The philosophy is, “NEVER pass along defective item”
Quality at the Source
36. 36
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A philosophy that rejects batch, lot or mass processing as
wasteful
States that product should move (flow) from operation to
operation, only when it is needed, in the smallest increment
One piece is the ultimate (one-piece-flow)
One Piece Flow
37. 37
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Continuous Flow
• Line up all of the steps that truly create value so they occur
in a rapid sequence
• Require that every step in the process be:
• Capable – right every time (6 Sigma)
• Available – always able to run (TPM)
• Adequate – with capacity to avoid bottlenecks
(right-sized tools)
38. 38
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Linking manual and machine operations into the most
efficient combinations to maximize value-added content
while minimizing waste
Elimination of work stagnation in and between processes
Ideal creation of one piece flow: making one part and
moving one part (in contrast to batch and queue material
handling)
In order to really get and hold the benefits of flow
production the organization must transition from a
functional structure to a product-focused, cross-functional
structure
Continuous Flow
39. 39
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Actual customer demand drives the manufacturing process
It creates a system of cascading production and delivery
instructions from downstream demand to upstream production in
which nothing is produced by the upstream supplier until the
downstream customer signals a need
The rate of production for each product is equal to the rate of
customer consumption
Pull Production
40. 40
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Pull Production
• Through lead time compression & correct value
specification, let customers get exactly what’s wanted
exactly when it’s wanted:
• For the short term: Smooth pull loops to reduce
inventory
• For the near term: Make-to-order with rapid response
time
• For the long term: Diagnostics and prognostics in a
stable relationship to take out the surprises for
consumers and producers
41. 41
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Pull System
Sub
Sub
Fab
Fab
Fab
Fab
Customers Final Assy
Vendor
Vendor
Vendor
Vendor
....
Production
Schedule
Leveled assembly
instructions
A
A
C
A
B
Vendor
42. 42
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20 20
Pull - The Continuing Need!
SHIPPING
Customer
X 0 X 0
Action A
Action B
Batch
tote
43. 43
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Standardized work consists of three elements:
Takt time
Matches the time to produce a part or finished product
with the rate of sales. It is the basis for determining
workforce size and work allocation
Standard in-process inventory
The minimum number of parts, including units in
machines, required to keep a cell or process moving
Standard work sequence
The order in which a worker performs tasks for various
processes
Once a standard work is set, performance is measured and
continuously improved
Standardized Work
44. 44
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Standardized work is the documentation and
application of the best practices of a manufacturing
process
It may include photographs and/or drawings
It ensures that production operations are performed
the same way each time
It is developed with the process/production operators
It is posted at each workstation
Standardized Work
45. 45
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Standardization/Simplification
Eliminate inherent sources of variance
Eliminate opportunity for human discretion error
Examples
• Container sizes
• MacDonalds with interaction with customers
Consistent with Deming Wheel
• Standardize expose problems solve
problems implement new methods
46. 46
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Work balancing maximizes operator efficiency by matching
work content to TAKT time
TAKT time is the rate at which customers require your
product
TAKT time is calculated as follows:
Available work time per day
Daily required customer demand in parts per day
Work Balancing / TAKT Time
47. 47
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TAKT Time
TAKT
• the beat
• (Net Available Operating Time) / Customer Requirements
• time periods must be consistent
48. 48
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TAKT Time Example
Net Available Operating Time
• Time per shift 480´ (minutes)
• Breaks (2 @ 10´) - 20´
• Clean-up - 20’
• Lunch - 30’
• NAOT/shift 410´
Customer Requirements
• Monthly 26,000 units/month
• No. Working Days 20 days/month
• CR/Day 1,300 units/day
TAKT Time
• 410’ x 60” x 3 shifts (73,800) divided by 1,300
• 57.769 seconds per part or 57"
49. 49
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Averaging both the volume and the production sequence of
different model types on a mixed-model production line
Example: Toyota Manufacturing
Toyota makes 3 car models - a convertible, hardtop, and an
SUV. Assume that customers are buying nine convertibles,
nine hardtops, and nine SUVs each day. What is the most-
efficient way to make those cars?
Production Smoothing / Leveling
50. 50
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One solution would be for Toyota to make all nine convertibles in
the morning, all nine hardtops in the afternoon, and all nine SUVs
in the evening. That would allow people to concentrate on one kind
of work at a time.
However, the people who make parts for the convertibles would be
busy in the morning, but they and their equipment would be idle in
the afternoon and evening. Similarly, the people and equipment
that make the parts for the hardtop and SUVs would be busy
sometimes and idle at other times.
.
Production Smoothing / Leveling
51. 51
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In the staging lot, vehicles would pile up between the plant and the
dealers. Customers don't buy nine convertibles in the morning, nine
hardtops in the afternoon, and nine SUVs in the evening. They buy
different kinds of cars through the day and week.
Ideally, an automaker needs to make different types of vehicles at more
or less the same pace that customers buy them. Otherwise, they will
end up with a lot of extra inventory in the form of unsold cars.
Production Smoothing / Leveling
Parts Factory Car Factory Dealer
52. 52
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Toyota solved the problem by production leveling.
If customers are buying nine convertibles, nine hardtops, and nine
SUVs each day, Toyota assembles three of each in the morning,
three of each in the afternoon, and three of each in the evening. It
also distributes the production of convertibles, hard tops, and SUVs
as evenly as possible through each shift: convertible, hard top, SUV,
convertible, hard top, SUV, and so on.
Production Smoothing / Leveling
53. 53
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Leveling production also helps to avoid the problem of excess
inventory of finished vehicles. The vehicle plants make the
different types of cars at about the same pace that customers buy
those cars. They can adjust the pace of production as buying
patterns change.
As the result, dealers only need to maintain a minimal inventory of
cars to show and sell.
Production Smoothing / Leveling
Parts Factory Car Factory Dealer
54. 54
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Wrap-up - Pull Manufacturing
Lean manufacturing is really about minimizing the
need for overhead
which is about concentrating precisely on only what
is necessary
which is about linking interdependent supply
system decisions, and actions
which needs to be visual, responsive and simple to
manage