Chapter 15
Lean
operations
and JIT
Source: Tibbet and Britten
Slack, Chambers and Johnston, Operations Management 5th Edition © Nigel Slack, Stuart Chambers, and Robert Johnston 2007
Lean operations and JIT
Operations
strategy
Lean operations and JIT
The market requires …
specified time, quantity and
quality of products and
services
The operation supplies …
the delivery of products and
services only when needed
Design
Operations
management
Improvement
Planning and
control
Slack, Chambers and Johnston, Operations Management 5th Edition © Nigel Slack, Stuart Chambers, and Robert Johnston 2007
‘The key principle of lean operations is relatively
straightforward to understand: it means moving
towards the elimination of all waste in order to
develop an operation that is faster and more
dependable, produces higher quality products
and services and, above all, operates at low cost.’
Slack, Chambers and Johnston, Operations Management 5th Edition © Nigel Slack, Stuart Chambers, and Robert Johnston 2007
Synonyms
continuous flow manufacture
high value-added manufacture
stockless production
low-inventory production
fast-throughput manufacturing
lean manufacturing
Toyota production system
short cycle time manufacturing
Source: Corbis/Denis Balihouse
Slack, Chambers and Johnston, Operations Management 5th Edition © Nigel Slack, Stuart Chambers, and Robert Johnston 2007
JIT material flow
Traditional approach
stage A
buffer
inventory
stage B
buffer
inventory
stage
C
JIT approach
orders
orders
stage B
stage A
deliveries
stage C
deliveries
Slack, Chambers and Johnston, Operations Management 5th Edition © Nigel Slack, Stuart Chambers, and Robert Johnston 2007
JIT and capacity utilization
Traditional
approach
focus on producing
only when needed
JIT
approach
fewer stoppages
focus on high
capacity utilization
lower capacity
utilization, but
more stoppages
because of
problems
more production
at each stage
high inventory
means less chance
of problems being
exposed and solved
extra production
goes into inventory
because of continuing
stoppages at stages
low inventory so
problems are
exposed and
solved
no surplus
production goes
into inventory
Slack, Chambers and Johnston, Operations Management 5th Edition © Nigel Slack, Stuart Chambers, and Robert Johnston 2007
JIT definitions
JIT aims to meet demand instantly, with perfect quality and no waste
More fully:
Improved overall productivity and elimination of waste
Cost-effective production and delivery of only the
necessary quantity of parts at the right quality, at
the right time and place, while using a minimum
amount of facilities, equipment, materials and
human resources
JIT is dependent on the balance between the
supplier’s flexibility and the user’s flexibility
JIT is accomplished through the application of
elements that require total employee involvement
and teamwork
Source: Empics
A key philosophy of JIT is simplification
Slack, Chambers and Johnston, Operations Management 5th Edition © Nigel Slack, Stuart Chambers, and Robert Johnston 2007
The lean philosophy of operations is the basis for JIT
techniques that include JIT methods of planning and control
The lean philosophy of operations
Eliminate waste
Involve everyone
Continuous
improvement
JIT as a set of techniques for managing
operations
Basic working practices
TPM
Design for manufacture
Set-up reduction
Operations focus
Total people involvement
Small, simple machines
Visibility
Flow layout
JIT supply
JIT as a method of
planning and control
Pull scheduling
‘Kanban’ control
Levelled scheduling
Mixed modelling
Synchronization
Slack, Chambers and Johnston, Operations Management 5th Edition © Nigel Slack, Stuart Chambers, and Robert Johnston 2007
The 5 S’s
Sort (Seiri) Eliminate what is not needed and keep what is needed.
Straighten (Seiton) Position things in such a way that they can be
easily reached whenever they are needed.
Shine (Seiso) Keep things clean and tidy; no refuse or dirt in the work
area.
Standardize (Seiketsu) Maintain cleanliness and order – perpetual
neatness.
Sustain (Shitsuke) Develop a commitment and pride in keeping to
standards.
Slack, Chambers and Johnston, Operations Management 5th Edition © Nigel Slack, Stuart Chambers, and Robert Johnston 2007
Delivering smaller quantities more often can reduce
inventory levels
Inventory
level
Inventory
level
Slack, Chambers and Johnston, Operations Management 5th Edition © Nigel Slack, Stuart Chambers, and Robert Johnston 2007
Waste (muda)
Activities:
operation
movement
Which of these symbols signify non-valueadding activities?
Types of waste:
over-production
waiting time
transport
inspection
process
inventory
delay
storage
motion
defective goods
 influencing the throughput efficiency
Slack, Chambers and Johnston, Operations Management 5th Edition © Nigel Slack, Stuart Chambers, and Robert Johnston 2007
The problem with inventory
productivity
problems
Reduce the level
of inventory (water)
to reveal the
operations’ problems
WIP
Defective
materials
Scrap
Rework
Downtime
WIP
Defective
materials
productivity
problems
Scrap
Rework
Downtime
Slack, Chambers and Johnston, Operations Management 5th Edition © Nigel Slack, Stuart Chambers, and Robert Johnston 2007
Small machines
The conventional Western approach is to purchase large
machines to get ‘economies of scale’.
These often have long, complex set-ups, and make big
batches, quickly creating ‘waste’.
Slack, Chambers and Johnston, Operations Management 5th Edition © Nigel Slack, Stuart Chambers, and Robert Johnston 2007
Using several small machines rather than one large one
allows simultaneous processing, is more robust
and is more flexible
JIT small machines approach:
easy to move (layout)
quick set-up
flexible scheduling options
cheaper tooling
planned maintenance easier
fewer set-ups needed
emphasis:
flexibility
economies of scope
Slack, Chambers and Johnston, Operations Management 5th Edition © Nigel Slack, Stuart Chambers, and Robert Johnston 2007
Visible, enforced improvement
‘Traditional’ production systems often accept waste and use the
insurance of all types of inventory
In JIT systems:
gradual reduction of inventory
identify exposed problems
eliminate these problems
repeat the cycle
emphasis:
continuous improvement in
small steps, to expose waste
and eliminate it
Slack, Chambers and Johnston, Operations Management 5th Edition © Nigel Slack, Stuart Chambers, and Robert Johnston 2007
JIT, MRP, or both?
complex
structures
PERT
MRP
JIT and/or
MRP
simple
structures
JIT
simple routings
complex
routings
Slack, Chambers and Johnston, Operations Management 5th Edition © Nigel Slack, Stuart Chambers, and Robert Johnston 2007
Key Terms Test
Just-in-time (JIT)
A method of planning and control and an operations
philosophy that aims to meet demand instantaneously
with perfect quality and no waste.
Kaizen
Japanese term for continuous improvement.
Set-up reduction
The process of reducing the time taken to change over a
process from one activity to the next; also called single
minute exchange of dies (SMED) after its origins in the
metal pressing industry.
Slack, Chambers and Johnston, Operations Management 5th Edition © Nigel Slack, Stuart Chambers, and Robert Johnston 2007
Key Terms Test
Single minute exchange of dies (SMED)
Alternative term for set-up reduction.
Andon
A light above a workstation that indicates its state: whether
working, waiting for work, broken down, etc. Andon lights
may be used to stop the whole line when one station
stops.
Slack, Chambers and Johnston, Operations Management 5th Edition © Nigel Slack, Stuart Chambers, and Robert Johnston 2007
Key Terms Test
Kanban
Japanese term for card or signal; it is a simple controlling
device that is used to authorize the release of materials
in pull control systems such as those used in JIT.
Levelled scheduling (Heijunka)
The idea that the mix and volume of activity should even
out over time so as to make output routine and regular,
sometimes known by the Japanese term ‘heijunka’.
Slack, Chambers and Johnston, Operations Management 5th Edition © Nigel Slack, Stuart Chambers, and Robert Johnston 2007