Transcript Intorduction to Project Management

MENG 447
Manufacturing Systems Automation
Chapter 1*
*Based on information from
Groover, 2001. Automation,
Production Systems, and
Computer-Integrated
Manufacturing.
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The Production System
Manufacturing
support systems
Manufacturing facilities:
factory, equipment
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Discrete Manufacturing
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Variety
Job shop
Batch Production
Mass Production
Material Handling Complexity
Discrete Manufacturing
Quantity
Automation
Specialization
Skills
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Discrete Manufacturing
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Mass production*
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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
* Check the textbook on the two types: quantity and flow line
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Discrete Manufacturing
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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
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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
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Facility Layout
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Four types of layouts:
Fixed Position: suitable for large products
Process: suitable for job shop
Cellular: suitable when products are similar in batch
production and sometimes in job shop
Product flow: suitable for mass production
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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
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Facility Layout
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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
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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
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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
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Facility Layout/Production Level
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Manufacturing Support Systems
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Automated Manufacturing Systems 3
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Machines
Transfer lines
Assembly
Material Handling
Inspection (coordinate measuring machines, CMM)
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Types of Automation
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Fixed Automation (transfer lines)
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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
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Types of Automation
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Programmable Automation (NC, CNC, robots- e.g., chess)
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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
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Types of Automation
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Flexible Automation (e.g., piston head)
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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
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Types of Automation
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Reasons for Automating
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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
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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
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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)
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Manual Labor in Automated Systems 5
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Strengths of Humans
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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
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Manual Labor in Automated Systems 5
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Strengths of (computer-based) machines
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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
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Manual Labor in Automated Systems
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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
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USA Principle:
1. Understand the existing process
2. Simplify the process
3. Automate the process (if needed)
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AUTOMATION PRINCIPLES AND STRATEGIES
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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
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