Production Systems Flashcards
(38 cards)
What is a process?
A piece of equipment for
carrying out a manufacturing task
What is a strategy?
A sequence of processes
appropriate to turn the raw material into the finished product, with the
necessary Quality Assurance
What is a system?
The physical representation
of the strategy within an industrial environment, with appropriate factory
management (e.g production lines,
batching, inspection)
What are the five production types?
● Project*
● Job
● Batch
● Flow - Assembly
● Flow - Continuous
What is job production?
One-off manufacture of individual, customised products; highly-skilled workers moving between processes; low equipment utilisation; flexible production schedule; can be difficult to plan
What is batch production?
Batches of standardised products move between
processes; higher utilisation than Job production; cost of storing WIP; batch size dependent on product and process
What is flow production?
Continuous manufacture of standardised products along a production line with high equipment utilisation; rigid production schedule
with limited flexibility; relies on predictable customer demand
What does a process plan include?
○ Operation number
○ Features to process/create
○ Tools and machines to use
○ Fixtures to use
○ Set up time
○ Processing time
○ Inspection requirements
In a process plan, how are the operations numbered?
● Often, the operation numbering will be in steps of 10 or 20
● This allows for additional processes to be added in later without needing to renumber the whole sequence
What does scheduling determine?
How many components to produce and in what order
● Good scheduling:
○ Meets the customer demand
○ Avoids overproduction
○ Avoids excessive Work In Progress (WIP)
What is product-driven layout?
● Used for discrete flow production (e.g
Glass bottles, alloy wheels, steel making)
● ʻProduction linesʼ or ʻAssembly linesʼ
dedicated to each product
● Process plan indicates the sequence of
processes
● Conveyors/rollers manage transport
between processes
● Lines may converge at shared processes
(e.g. heat treatment)
What are the advantages of product-driven layout?
● Highly visual for the operator and
management
● Products are visible all along the line
● Easy to see if the processes are running
smoothly
● Bottlenecks and breakdowns can be
readily identified
● Easy to monitor production rates
What is process-driven layout?
Used for job (and batch) production (e.g. a machine
shop, or a gym!)
● Driven by efficient use of space and access
for services
● Machines are often grouped by type
● Little similarity in the process plan across
products, so no single ʻbestʼ route
● Travel time and route different for every
product
What are the advantages of process-driven layout?
● Tooling & services can be shared
● Operators can see machine availability
● Maintenance can be carried out on all
machines simultaneously
● Easy to spot when one machine is
operating poorly compared with the
others
What are the disadvantages of process driven layout?
● Often poor line of sight across the factory
● Cannot see how WIP is moving from start
to finish
● Harder to spot breakdowns and
bottlenecks
● Higher risk of products getting lost
What is multi-factory layout?
● Used for continuous flow production (e.g.
oil, water, electricity)
● Factory spread across multiple buildings
and facilities
● Each dedicated to a particular function
What are the advantages of multi-factory layout?
High level of automation across the facility
Physical pipelines used to transport product between processes
What are the disadvantages of multi-factory layout?
● High investment in buildings,
equipment and processes
● Too large for direct visibility of flow
● Requires remote monitoring
What is fixed product layout?
● Used in project production (e.g. house
building, aircraft assembly)
● The product is large and cannot be moved
between processes
● Normally used for assembly rather than
manufacture
● Operators and equipment must come to
the product
What is Processing (Touch, Cycle) Time?
● The ʻadding valueʼ time that workers
spend doing ʻstuffʼ to the product
● E.g. drilling, painting, filling a mould
What is Repositioning (Set-Up) Time?
● Moving parts, tools, people etc. to
enable the ʻadding valueʼ activities
● E.g. parts moving on conveyor,
workers fetching components
What is Work Content?
Processing time + Repositioning time
What is Waiting (Idle) Time?
The time that a part waits after completing one process before
starting the next one
What is a Bottleneck?
● A process restricting throughput
● Normally identified by an increase
in waiting time or WIP
