Process choice
and production layout
Marja Blomqvist, Patrick Appelqvist
19.10.2005
The product-process matrix
High
variety
Project
Too expensive
Jobbing
Batch
Repetitive
Not competitive
Continuous
Low
variety
Low
Volume
High
Volume
Project: Wedding cake
The product is unique
The product is
assembled on-site because it is
so large
Variety
Not to be confused with
projects in general
Proj
Job
Batch
Rep
Cont
Volume
How projects are arranged:
Fixed lay-out
•
•
•
•
Variety
•
Keeping the
timetable
Schedule resources
Continuous
replanning
Extreme material
flow (T-shaped)
Approached with
planning software
Proj
Job
Batch
Rep
Cont
Volume
Jobbing:
Restaurant kitchen
Special products are
made in low volumes
by skilled workers.
Variety
Not ”industrial-level”
efficiency
Proj
Job
Batch
Rep
Cont
Volume
Challenges in jobbing
Variety
• High product variety,
low volumes (e.g.
consulting, handicraft
furniture makers)
• Requires skilled
people.
• Investments are low.
Proj
Job
Batch
Rep
Cont
Volume
How jobbing is arranged:
Functional lay-out
• Same type of machines
together.
Rep
Cont
Paint
booth
Batch
Boring
machine
Job
Milling
machines
Drilling
machines
Lathes
Variety
• Workers move products
depending on needed
processes.
Proj
Work benches
Work benches
– Functional layout
– Alternatively cellular
production
Batch process: Bakery
A batch of similar
products are made
at a time.
Provides higher
efficiency than
jobbing.
Variety
Usually implosive
material flow.
Proj
Job
Batch
Rep
Cont
Volume
How batch is arranged:
Process lay-out
Variety
Proj
Job
Batch
Rep
Cont
Volume
Sonic welding
Injection moulding machines
• Stop-and-go
processes
• Processspecialised
machines and
workers
• Production
scheduling
• Process lay-out
D
Work-inprogress
Final
assembly
D
Work-inprogress
Screen
printing
D
Hot-roll
stamping
Final
assembly
Repetitive: Pizza manufacturing
The product moves
according to a fixed
route.
Variety
Possible for very
high volumes as
investments are
huge
Proj
Stopping
the line is
Job
Batch
very expensive
Rep
Cont
Volume
How repetitive mfg is arranged:
Product lay-out
•
•
Processes divided in steps of equal
duration and arranged in the
sequence product needs them.
Fixed production / assembly line
– Cycle time; forced movements of
products
– Stopping the line is very expensive
•
Flow line
– Non-forced; buffers between the
stations
Variety
•
Low skills needed, boring work;
Taylorism
Proj
Stopping
the
line
is
Job
Batch
very expensive
Rep
Cont
Volume
Continuous flow process:
Beer brewing
A homogenous product
flows through dedicated
pipes.
High investment on facilities;
capacity level changes slow
and costly.
Variety
In contrary to batch and
repetitive, often explosive
material flow.
Proj
Job
Batch
Rep
Cont
Volume
How continuous production is arranged
Variety
• Expensive, specialpurpose equipment
• Few, skilled
workers
• Focus in capacity
utilisation
Proj
Job
Batch
Rep
Cont
Volume
Summary of the layout options
Functional
i.e. Process
lay out
Cellular
Flow
i.e. Product layout
(Group Technology!)
Line
Improvement of production flow
•
•
Importance of production flow: main indicator of manufacturing smoothness
Indicators for improvement need:
– Many units on carts, shelves, conveyors floors waiting to be assembled or further
processed
– Visible reject parts that have not been disposed or repaired
– Numerous rework benches or large amount of rework operations in the normal
production
– Workers hanging around idle
– Expensive machinery or known bottleneck that is idle
– Expediting of high priority work orders on factory floor
– Trash on the floor, on the tables, on the shelves
– Unplanned partial assemblies carried out due to part shortages / unplanned
capacity problems
– Machine operators sorting out defect incoming parts
– Daily or frequent ad hoc production status meetings on firefighting basis.
– Delivery on time, throughput time, yield and other main measures not visible on
factory floor
Summary
1.
High
variety
2.
3.
4.
Process choice is a strategic
choice.
Depending on process, both
challenges and solutions are
different
Production lay-out is the
implementation of the chosen
process
The process types are
presented as stereotypical
cases: however, in reality the
line between different types is
sometimes fuzzy.
Low
variety
Low
Volume
High
Volume
Backup
Burbidge’s six laws on production
system design (1)
• Law of the whole and its form: The whole is not a
mere sum of its parts, and a set of subobtimised
solutions never yield to a truly optimal whole
solution.
• Law of material flow: The efficiency of production
is inversely proportional to the complexity of
material flow.
• Law of forecasting: Only few have psychic skills
of seeing things before they happen. Use short
planning cycles.
Burbidge’s six laws on production
system design (2)
• Law of system dynamics: If demand variations
have a chance to amplify throughout the steps of
production chain due to its structure, this is bound
to happen even under normal circumstances.
• Law of ordering cycles: If parts and components
are manufactured and orderd in different cycles,
large variances and unexpected changes both in
inventories and capacity needs are unavoidable.
• Law of interdepencences: Every consequence
has many root causes and vice versa.