Just In Time ….
Just in Time Philosophy
Salient features
 The notion of waste in any operating
system
 JIT as a philosophy of elimination of
waste
 As a deliberate and a systematic attempt
 On a continuous basis
Just In Time Manufacturing
Water Flow Analogy
Unrealistic
Variable
Defective
Poor
schedules
Lack
Processing
Material
Quality
of
Times
training
Machine
Inadequate
Bottleneck
Breakdown
Information
Behavioural/Managerial constraints
JIT Philosophy
Core Logic
Deliberate withdrawal
of buffer inventories
Heightened
awareness of
problems & causes
Ideas for
cutting
lot sizes
Lot size
reductions
Less
inventory
Ideas for
improving
JIT delivery
Ideas for
controlling
defects
JIT
Productions
Reduced buffer
inventories
Fast feedback
on defects
Scrap/quality
control
Less indirect costs
Smoother
output rates
Fewer
rework
Less
material waste
High quality
Finished goods
Less material, labour, indirect costs & better quality
Source: Schonberger, R..J. (1982), “Japanese Manufacturing Techniques: Nine hidden lessons in simplicity”, Free Press, pp 26.
JIT Philosophy
Overall Impact
JIT Logic




Withdraw buffer “deliberately”
Thereby expose hidden
problems in the system
Identify solutions to the
problems, implement and
attain smooth production rates
Repeat the above steps
JIT Overall Impact


Faster feedback on Quality
Quality Improvement

Tightly linking preceding and
subsequent processes

Increased responsibility effects
JIT Manufacturing
Basic Elements
 It originally referred to the production of goods
to meet customer demand exactly, in time,
quality and quantity, whether the `customer' is
the final purchaser of the product or another
process further along the production line.
 It has now come to mean producing with
minimum waste. "Waste" is taken in its most
general sense and includes time and resources
as well as materials.
Elements of JIT include:

Just-in-time' is a management philosophy and not a technique.

Continuous improvement.

Attacking fundamental problems - anything that does not
add value to the product.

Striving for simplicity - simpler systems may be easier to
understand, easier to manage and less likely to go wrong.

Quality control at source - each worker is responsible for the
quality of their own output.
Poka-yoke - `foolproof' tools, methods, jigs etc.
prevent mistakes
Preventative maintenance, Total productive
maintenance - ensuring machinery and equipment
functions perfectly when it is required, and continually
improving it.
Good housekeeping - workplace cleanliness and
organisation.
Set-up time reduction - increases flexibility and allows
smaller batches. Ideal batch size is 1item.
Multi-process handling - a multi-skilled workforce has
greater productivity, flexibility and job satisfaction.
Kanbans - simple tools to `pull' products and
components through the process.
Jidoka (Autonomation) - providing machines with the
autonomous capability to use judgement, so workers can
do more useful things than standing watching them
work.
Andon (trouble lights) - to signal problems to initiate
corrective action.
Eliminating waste. There are seven types of waste:
waste from overproduction.
waste of waiting time.
transportation waste.
processing waste.
inventory waste.
waste of motion.
waste from product defects.
Lean Manufacturing
Eliminating waste. There are seven types of waste:
14
PUSH Scheduling
Internal
Focus
Long Lead
Times
Utilisation
Push
Quantity
Driven
Measurements
High
Demand
Forecast
High Fixed
Costs
INVENTORIES
Forecast drives production
PULL Scheduling
Profit Based
Measurement
Low
Demand
PULL
Finished Goods
External Focus
Factory
Flexibility
Faster
Response
Customer Order
Customer triggers production
PUSH – PULL
Impact on the system
Issues to Consider
Responsibility to
monitor
Flow control
Signal to build
Inventory
Problems
Communication
between Operations
React time:
Changes/problems
Visible indication of
problem
Shop floor control
Push Scheduling
Scheduler/system
Pull Scheduling
People in mfg.
If all standards are met Always
Schedule/system
Visible - from customer
No limit – higher
Limits – lower
Can be hidden
Exposed - creates
urgency
By chance – operations By necessity
work on their orders
Through the system rescheduling required
Immediate - on-line
and visible
Inventory
Production Stops
System, transactions,
paper work
Automatic, Visible &
Simple
Just in Time Manufacturing
 JIT systems have an unambiguous definition of
what constitutes waste in the system.
 The philosophy of Just in Time system is one of
continuous waste elimination.
 Contrary to the traditional thinking, the inventory in
a JIT system is deliberately removed to expose
hidden problems.
 These problems are solved resulting in fewer
inventory and waste in the system and greater
productivity.
 Implementation of JIT requires that the
manufacturing architecture is converted into a
chain of internal customers.
 Lot size reduction and use of standard containers
are other elements of a JIT system.
Just in Time Manufacturing
 Production Planning and control in JIT systems is
achieved through the use of Kanban
 Kanban enables waste elimination from the system
by preventing overproduction and exposing
problems in processes.
 JIT systems utilise a Pull type scheduling
 Pull type scheduling are very effective in providing
visible control of the processes and bringing the
problems to the surface rapidly.
End of Session