Introduction to lean philosophy
Avoid all types of waste in an operation, and reduce
cost. Thereby increase the profit.
In all operations there are many types of wastes such
as:
•
•
•
•
•
•
Spoilage
Overproduction
Excessive materials handling
Scrap
Rework and repair
Accidents and breakdowns
JIT ( JUST-IN-TIME)
JIT is the technique used to achieve the goals set
forth by the Lean Philosophy.
What is JIT?
Produce goods and services exactly when they
are needed.
In other words not before they are needed,
because it costs inventory, not after they are
needed, because the customers will be in
queue.
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
JIT and capacity utilization
focus on producing only
when needed
JIT approach
Traditional
approach
focus on high capacity
utilization
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
fewer stoppages
lower capacity
utilization, but
low inventory so
problems are
exposed and solved
no surplus
production goes
into inventory
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
I.
Eliminate waste
Avoid any type of waste in production. Waste is
any activity which does not add value.
There two devices used in lean operations for
improving the wastage:
1. The Seven Forms of Waste
2. The 5S’s
The seven forms of waste
• Over-production
• Waiting time (equipment efficiency, labour efficiency)
• Transport (moving items around the operation costs
and creates no value)
• Process – some process creates cost and add no value,
so proper design should be made.
• Inventory – all types of inventory should be eliminated.
• Motion – simplify the work and avoid waste of motion.
Avoid unnecessary work that add no value.
• Defectives – avoid quality waste.
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.
Methods for eliminating waste
1. Throughput time.
Throughput time is the key to find out the waste
factor in an operation. Throughput time is the
time taken for a product to come from a
particular production facility.
2. Value stream mapping
It is a technique that maps a product or service
production path from start to finish. It records
the direct activities and indirect information
systems in the production process.
‘Value stream’ mapping
‘Value
stream’ mapping focuses on value-adding activities. It
distinguishes between value-adding and non-value-adding activities.
It is similar to process mapping but different in four ways:
It uses a broader range of information than most process
maps.
It is usually at a higher level (5–10 activities) than most process
maps.
It often has a wider scope, frequently spanning the whole
supply chain.
It can be used to identify where to focus future improvement
activities.
There are four steps in the value
stream mapping as follows:
•
•
•
•
Identify (process, supply chain,opertion)
Mapping process
Diagnose problems and suggest changes.
Implement changes.
II. The Involvement of everyone
It is an approach to people management.
It encourages team based problem solving.
Job enrichment
Job rotation, multi-skilling
The main objective of this approach is to
encourage a high degree of personal
responsibility, engagement and ownership.
III. Continuous improvement
This approach is to achieve the ultimate goals of
lean philosophy over time or step-by-step.
The objective is to achieve good quality with no
waste, but any operation will be far from the
point, so it is continuous improvement
process.
JIT Techniques
1.Adopt basic working practices
This is same as involving everyone.
It includes the following:
1. Discipline – standard for safety, environment, quality of product.
2. Flexibility – ability to expand responsibilities
3. Equality – treat all the employees at the same level. For example
uniform and so on.
4. Autonomy – give responsibility
5. Development of personnel – preparing employees competitive.
6. Quality of working life- involvement in decision making,job
security, facilities in working area
7. Creativity – improve the job every time.
8. Total people involvement- staff use ability for the benefit of the
company .
2. Design for ease of processing
Design improvements can reduce the
production cost.
3. Emphasize operation’s focus
The main objectives are simplicity, repetition
and competence. Learn to focus each process
on limited, manageable sets of products,
technologies, volumes and markets.
4. Use small, simple machines
Small machines process different products and
services simultaneously.
5. Layout for smooth flow
Flow of materials, data, people must be in
smooth manner to avoid delay, increased
inventory and waste.
In lean philosophy work stations are closer to
avoid inventory.
6.Adopt total productive maintenance
This is to avoid unplanned breakdowns. This is achieved
by giving responsibility to process owners or staffs.
6. Reduce step times
Setup time is the time required to change the process
from one activity to other. Also known as single minute
exchange dies. This is achieved by:
1. pre-select tools so that a complete unit is fixed to
machines.
2. Attaching different tools to a standard fixture.
3. Facilitate loading and unloading of new tools.
7.Ensure visibility
The more transparent the operation the more
will be chances of improvement.
9. Adopt JIT through the supply chain
JIT can be used in whole supply chain. Here
stages in a process are the whole business.
JIT PLANING AND CONTROL
1. JIT uses the pull scheduling.
Poor inventory timing creates problems in
operations. Inventory timing is controlled by
two factors:
Push planning and control – parts or material
released as it finished.
Pull planning and control – material release is
only by request.
Methods of JIT planning and control
2. Kanban control(card or signal)
It is a method of operating pull-based control system,
where material is released when required.
Three types of Kanban:
1. The move or conveyance Kanban – it is a signal to the
previous stage for withdrawing the materials from
inventory.
2. The production kanban – signal asking to start
producing an item to be placed in inventory.
3. The vendor kanban – signal for suppliers to feed parts
or materials.
Two procedures for controlling
Kanbans:
• Single –card systems
• Dual –card systems
1.Single –card systems – used when receiving
supply of material from an outside source.
2.Dual-card system – uses both production
kanban and move kanban
3.Synchronization
It means the pacing of output at each stage in the process
to make sure that the same flow characteristics in the
whole process.
4. Mixed Modeling
Producing steady stream of each item. For example if
200As, 120Bs, 80Cs, to be produced the mixed model
will produce it like AABABCABCA….
5.Levelled delivery schedule
Deliver smaller quantities of all the products in a delivery.
JIT in service industry
JIT can be used in service industry.
Examples of service JIT – PAGE 485
JIT and MRP
JIT is pull system of planning and control, while
MRP is push system. But it can be combined in
many operations.
Characteristics of MRP and JIT – PAGE 486
How JIT and MRP can be
combined?(coexist)
Both JIT and MRP re different approaches, but it
can be combined in several ways.
The way in which it can be combined depend on
the complexity of product structures, the
complexity of product routing, the volume –
variety charestristics and the level of control
needed.