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Mass production*
– Automation easily justified
– Objectives: (1) reduce operation cycle time, (2) increase system reliability
– Line is rarely changed - setup time not critical
– Inflexible: not suitable for products with many options or limited
production runs
Discrete Manufacturing
* Check the textbook on the two types: quantity and flow line
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Job shop production
– Products produced in small volume
– Automation difficult to justify unless products are too complex to
be produced manually
– Objectives: (1) reduce setup time, (2) reduce processing time, (3)
reduce WIP
– Most flexible of production strategies
Discrete Manufacturing
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Batch production
– Products produced in batches, lots or groups
– Trade-off between job shop and mass production
– Single setup for each batch
– Increase batch size, but increase in waiting time, WIP and
inventory result
– Objectives are same as job shop
Discrete Manufacturing
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Facility Layout
Four types of layouts:
Process: suitable for job shop
Fixed Position: suitable for large products
Cellular: suitable when products are similar in batch
production and sometimes in job shop
Product flow: suitable for mass production
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Process layout
– For small, discrete-parts manufacturing
– Machines are grouped into departments according to type of
operation
– Advantages: work schedule more flexible
– Disadvantages: WIP is large (cost in inventory and storage
space), high material handling cost, larger batches are made than
are required (to justify setup), difficulty in maintaining control of
parts, highest skill level required from operators
Facility Layout
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Fixed position layout
– Product must remain stationary throughout production sequence
– Machines are brought to the product
– Higher expense due to robustness and accuracy of equipment
Facility Layout
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Product flow layout
– Suited for high volume production
– Advantages: minimized material handling, easy to automate
material handling, less WIP, easier to control
– Disadvantages: inefficient to alter the sequence of operations,
breakdown on one machine can stop the entire line
Facility Layout
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Group technology (cellular) layout
– Several different types of machines are grouped together to form a
cell - each cell is designed to produce a family of parts
– Suitable for small to mid-volume production of parts
– Advantages: setup time is reduced, lead time is reduced, WIP is
reduced, finished inventory is reduced, improved quality (group of
workers responsible for a cell)
– Disadvantages: parts must be grouped into families, layout is less
flexible than process layout, batches from same family cannot be
run simultaneously, higher skill level required from operators
Facility Layout
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Example Industries
Aerospace
– Typically, complex, three-dimensional shapes, exotic
materials, medium-volume to low-volume production
quantities
– Military and space technology filters down to industrial
applications
– Pioneered work in NC machining, CAD/CAM,
composites and flexible manufacturing system
applications
– Goals: energy efficiency, high strength-to-weight ratio
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Example Industries
Automotive
– Relatively large production quantities, multiple options: automated
assembly is difficult
– Traditionally, primary processes were metalworking: machining of
power train parts, forming and bending sheet metal; assembly by
spot welding and mechanical fasteners; finishing by spray painting
and plating
– New materials: plastics, fiberglass
– Increasing automation: robots for spot welding and spray painting
– Improved quality with production groups that assemble large
portions of the automobile
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Example Industries
Chemical
– Chemical processes for man-made fibers and plastics,
oil distillation and pharmaceutical industries
– Continuous flow of product and byproducts; some batch
processing
– reasonably easy to automate
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Example Industries
Food
– Large volume industry
– Standard products and operations, therefore reasonably
easy to automate
– Many products use continuous processes; discrete
processes includes packaging
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Example Industries
Semiconductor
– Large volume industry
– Emphasis on design and production of low-cost
integrated circuits
– Smaller size and more stringent requirements for
cleanliness
– Process requirements have forced automation
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Increase production rate
eliminate portions of process that directly increase production time:
machine processing time, handling time, setup times (SMED)
Remove humans from hazardous environments
exposure to chemicals, fumes, temperature or radiation
robotic applications: L/UL furnaces, spray painting, welding
Remove humans from processes that require extremely clean
environments: e.g., semiconductors, drugs
Reduce number of defective products
Reduce direct labor
one worker monitors a larger number of machines
Reasons for Automating
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Reduce work-in-process
parts being processed, part waiting to be processed
large WIP: longer time to fill orders, more storage space, value of
unfinished goods that could be invested elsewhere
reduced WIP: better control and scheduling
Reduce manufacturing lead time
processing time, setup time, waiting time
setup time: flexible automation, common fixtures and tooling
processing time: combining or eliminating operations, increase
speed (work measurement principles)
Increase quality
repeatable operations through every cycle - tighter control limits,
easier detection when process is out of control
status of manufacturing operations
Reasons for Automating
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Increase productivity
Reduce labor cost
Address labor shortages
Reduce or eliminate routine manual and clerical tasks
Health and Safety
May be the only option
Stay up-to-date (avoid cost of catching up)
Reasons for Automating
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OSHA
Occupational Safety and Health Administration
The mission of the Occupational Safety and Health
Administration (OSHA) is to save lives, prevent injuries
and protect the health of America's workers. To
accomplish this, federal and state governments must
work in partnership with the more than 100 million
working men and women and their six and a half million
employers who are covered by the
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Machines
Transfer lines
Assembly
Material Handling
Inspection (coordinate measuring machines, CMM)
Automated Manufacturing Systems
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Fixed Automation (transfer lines)
– Hard automation, automation for mass production
– Produces large numbers of nearly identical parts
– High initial investment for custom engineered equipment
– Product design must be stable over its life
– Advantages: equipment fine tuned to application -
decreased cycle time, infrequent setups, automated
material handling - fast and efficient movement of parts,
very little WIP
– Disadvantage: inflexible
Types of Automation
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Programmable Automation (NC, CNC, robots)
– Sequence controlled by a program
– High investment in general purpose equipment
– Lower production rates
– Flexibility to deal with variation
– Suitable for batch production
– Smaller volumes (than fixed) of many different parts
– More flexible than fixed automation
– Major disadvantage: setup prior to each new part
– Large batch size (due to setups)
– Speed sacrificed for flexibility
Types of Automation
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Flexible Automation (FMS)
– Extension of programmable automation
– No time lost for change over
– High investment in custom-engineered systems
– Production of product mix
– Flexibility to deal with design variations
– Low to medium quantities
– Compromise between fixed and programmable automation in speed
and flexibility
– Advantage: programming and setup performed off-line
– More expensive - size and tool change capabilities
– Small batch sizes are justified - reduced WIP and lead time
– Typical parts are expensive, large and require some complex
machining
Types of Automation
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Strengths of Humans
– Sense unexpected stimuli
– Develop new solutions to problems
– Cope with abstract problems
– Adapt to change
– Generalize from observations
– Learn from experience
– Make difficult decisions based on incomplete data
Manual Labor in Automated Systems
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Strengths of (computer-based) machines
– Perform repetitive tasks consistently
– Store large amounts of data
– Retrieve data from memory reliably
– Perform multiple tasks simultaneously
– Apply high forces and power
– Perform computations quickly
Manual Labor in Automated Systems
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Manual Labor in Automated Systems
Even if all of the manufacturing systems in the factory are
automated, there will still be a need for the following kinds of
work to be performed:
•Equipment maintenance. Maintain and repair, improve the
reliability, of automated systems.
•Programming and computer operation.
•Engineering project work. Upgrades, design tooling, continuous
improvement.
•Plant management.
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AUTOMATION PRINCIPLES AND STRATEGIES
USA Principle:
1. Understand the existing process
2. Simplify the process
3. Automate the process
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AUTOMATION PRINCIPLES AND STRATEGIES
Ten Strategies for Automation
1. Specialization of operations.
2. Combined operations.
3. Simultaneous operations.
4. Integration of operations.
5. Increased flexibility.
6. Improved material handling and storage.
7. On line inspection.
8. Process control and optimization.
9. Plant operations control.
10. Computer integrated manufacturing (CIM).
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AUTOMATION PRINCIPLES AND STRATEGIES
Automation Migration Strategy
Phase 1: Manual production using single station manned cells
operating independently.
Phase 2: Automated production using single station automated
cells operating independently.
Phase 3: Automated integrated production using a multi-station
automated system with serial operations and automated transfer
of work units between stations.
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3500 BC Use of Wheel and axle for transportation
500 BC Lathe used for wood turning
1569 Screw-cutting lathe developed -- Jacques Besson
1769 James Watt invented the steam engine -- later used to
provide power to industry
1774 Precylinder-boring mill developed -- John Wilkinson
1790 Samuel Slater opens the first successful textile mill in the
United States
1793 Eli Whitney builds the first cotton gin
1798 Eli Whitney invents a milling machine to produce
standardized parts in muskets
Historical Development of Manufacturing
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1801 J.M. Jacquard invented a silk-loom-- punched cards controlled
the machine
1851 Issac Singer patented his sewing machine
1900 High-speed steel cutting tools developed
1903 Oxyacetylene welding torch developed
1903 First fully automated machine-made bottles produced
1907 Paint spray gun developed
1913 Ford Motor Co. opens first moving assembly line
1914 Centrifugal casting of cast iron pipe -- re-usable molds are used
1920 Ford introduces continuous casting of cast iron for engine
blocks
Historical Development of Manufacturing
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1921 Jigs and fixtures used in the jig-boring machine to make rifles
and revolvers -- Enfield, England
1930 First automatic factory -- Made chassis frames for cars: one
every six seconds
1952 First commercial NC machine
1962 First industrial robot
1963 Electro-coating methods for painting car bodies is developed
1964 Technique for fast-breaking electric motors developed --
machine tools can now be stopped quickly
1985 First products manufactured in space went on sale -- tiny plastic
beads, perfectly round and uniform in size
Historical Development of Manufacturing
