LEAN system
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LEAN referred as JIT (because the activities
and delivery of goods occur just as they are
needed)
Begun in the mid 1900’s, developed by
Toyota its goal is to eliminate every waste
from every aspects of the process
Waste – didn’t add value to the process
Value ws.waste
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"value" is defined as any action or process
that a customer would be willing to pay for
Waste
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muda ("non-value-adding work"),
muri ("overburden"), and
mura ("unevenness"),
The toyota approach
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Muda: waste and inefficiency must be
minimized by using the following technics
Kanban – a manual system responds to
signals of the need for delivery of parts and
materials (both to the factory and between
the workstation)
Pull system – produce only what is needed
Heijunka – work load must be leveled to
achive stedy flow of work
time
Not leveled workload
Worksteps
time
Leveled workload
Worksteps
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Kaizen – continuous improvement of the
system
Jidoka – each worker is expected to perform
ongoing quality assurance, objective is to
avoid passing defective products to the
following work station
Poka-Yoke – safeguards built into the
process to reduce the possibility of errors
JIT vs Ford system
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the JIT system rooted in the system of Henry
Ford,
But it can accomplish that Ford coludn’t: the
system that colud handle with variety
(product variety and range of volume)
Supporting goals
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A balanced system, smooth, rapid flow of
materials and/or work
To make a process time as short as possible
Supporting goals:
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Eliminate disruption
Make the system flexible
eliminate waste, especially exess inventory
1. Disruption
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It upsets the smooth flow of the system
It is caused by
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poor quality,
equipment breakdowns,
late deliveries
2. Flexible system
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A system which is robust enough to handle a mix of
products and changes in the level of output
Short setup time (Period required to prepare a
device, machine, process, or system for it to be
ready to function or accept a job.)
Short lead time (is the period of time between the
initiation of any process of production and the
completion of that process.)
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Lead time for ordering a new car from a manufacturer may be anywhere
from 2 weeks to 6 months
3. waste
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The key step in LEAN is the identification of which
steps add value and which do not:
A process adds value by producing goods or
providing a service that a customer will pay for.
value-adding work has been separated from waste
then waste can be subdivided into 'needs to be done
but non-value adding' waste and pure waste.
There are 7 wastes in LEAN
(TIMWOOD):
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Inventory - represents a capital outlay that has not yet produced
an income either by the producer or for the consumer. It takes up
floor space and adds to cost.  inventory must be minimized
Overproduction – engage more resources than needed to deliver
to the customers. It is because batch production. Because of
productivity improvement, operators are required to produce
more than customer needs. It generates all other wastes,
especially inventory.
Waiting - Whenever goods are not in transport or being
processed, they are waiting. (becouse of not leveled workload.
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Unnecessary transportation - Each time a product is moved it
stands the risk of being damaged, lost, delayed, etc. as well as
being a cost for no added value. Transportation does not make
any transformation to the product that the consumer is supposed
to pay for.
Processing waste – unecessary steps of production, moves of
workers, searching activities for tools,
Defects - Whenever defects occur, extra costs are incurred
reworking the part, rescheduling production,
Inefficient work methods – decrease productivity, for example
inefficient replacement of inventory’s, continuous quality check
Kaizen
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The wastes are potential tartgets for
continuous improvement, called kaizen.
JIT Building Blocks
 Product
design
 Process
design
 Personnel/organizational
elements
 Manufacturing
planning and control
Product Design
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Standard parts – fewer parts to deal with lower
training costs
use standard processing
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Modular design – clusters of partsn treated as a
single unit.  easy to satisfy different needs
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Highly capable production systems – quality is
designed into the product and the production
process
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Concurrent
engineering
Process Design
 Small
lot sizes
 Setup time reduction
 Manufacturing cells
 Limited
work in process
 Quality improvement
 Production flexibility
 Little
inventory storage
Benefits of Small Lot Sizes
Reduces inventory
Less rework
Less storage space
Problems are more apparent
Increases product flexibility
Easier to balance operations
Production Flexibility
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Reduce downtime by reducing
changeover time - small lots require
frequent setups.
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SMED (single minute exchange of die)
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External
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Internal activities.
Use preventive maintenance to reduce
breakdowns
Manufacturing cells
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In Functional Manufacturing
similar machines are placed
close together (e.g. lathes,
millers, drills etc)
In Cellular Manufacturing
systems machines are
grouped together according to
the families of parts produced.
The major advantage is that
material flow is significantly
improved, which reduces the
distance travelled by materials,
inventory and cumulative lead
times.
Quality improvement
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Autonomation – automatic detection of
defects during production. It referres to jidoka
It consist two activities:
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One for detecting defects when they occure
Another for stopping production to correct the
cuase of defects.
Work flexibility
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Overall goal of lean is to achieve the ability to process
mix of products in a smooth flow.
One potential obstacel is botlenecks, which occure
when portions of the system become overloaded.
Balanced system
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Distributing te workload evenly among workstations
Takt time – is the cycle time needed in the production system to
match th pace of production to the demand rate
Example:
 Total time per shift is 480 minutes per day
 There are two shifts per day
 There are two 20-minutes break and a 30 minutes lunch break
per shift.
 Daily demand is 80 pieces
Net time available per day= 2*(480-20*2-30)=820minutes
Takt time=820minutes/80 pieces=10,25 minutes
If the actual ciycle time is higher, our customers won’t get their
needs, if the actual cycle time is lower, there will be
overproduction, and we have to inventory surplus products.
Inventory sorage
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Inventory storage in the lean philosophy is a waste, a buffer
which can cover up problems, partly beause iventory makes
them seem less serious.
When a machine breaks down it won’t disrupt the system if there
is a sufficient inventory of the machine’s output.
Lean approach is to eliminate inventories in order to uncover the
problems and solved. Then the systme removes more inventory,
finds and solves additional problems.
One way of minimizing inventory is to have delivers from
suppliers go directly to the product floor . At the end of the
process completed units shipped out as soon as possible-JIT
But less inventory has also some risk: if a problem arises there is
no safety net.
Fail- Safe methods
The same as poka-yoke, when safeguards are
built into a process to reduce or eliminate the
potential errors.
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The contact method identifies product defects by testing
the product's shape, size, color, or other physical
attributes.
The fixed-value (or constant number) method alerts the
operator if a certain number of movements are not
made.
The motion-step (or sequence) method determines
whether the prescribed steps of the process have been
followed.
Alarm if the weight of a packaged item is too low,
ATM signal ifthe card is left in the machine
Personnel/Organizational Elements
 Workers
as assets
 Cross-trained
workers
 Continuous
improvement
 Cost
accounting
 Leadership/project
management
Manufacturing Planning and Control
 Level
 Pull
loading
systems
 Visual
systems
 Close
vendor relationships
 Reduced
transaction
processing
 Preventive
maintenance
Level loading
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Mixed model sequencing
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Choice of sequencing (minimal setup
cost, or time)
The number of cycles per day –
smallest integer
Number of units – daliy demand
divided by number of cycles
Pull/Push Systems
 Pull
system: System for moving work
where a workstation pulls output from the
preceding station as needed. (e.g.
Kanban)
 Push
system: System for moving work
where output is pushed to the next
station as it is completed
Kanban Production Control System
 Kanban:
Card or other device that
communicates demand for work or
materials from the preceding station
 Kanban
is the Japanese word meaning
“signal” or “visible record”
 Paperless
 Authority
production control system
to pull, or produce comes
from a downstream process.
Close vendor relatonship
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JIT
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Frequent small delivers
Deliver next to the workstation
No quality check
Local vendors
Tradtitonal
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List of suppliers
Buyer play vendors off against each other
Price is the most important
No loyalty
Traditional Supplier Network
Figure 12.4a
Buyer
Supplier
Supplier
Supplier
Supplier
Supplier
Supplier
Supplier
Tiered Supplier Network
Figure 12.4b
Buyer
First Tier Supplier
Second Tier Supplier
Third Tier Supplier
Supplier
Supplier
Supplier
Supplier
Supplier
Supplier
Supplier
Preventive maintenance and housekeeping
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5S
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Sort –decide which item is needed
Straighten – needed items can be assessed
quickly
Sweep – clean workplace
Standardize – use standard intructions
Self discipline – make sure that employees
understand the need for uncluttered workplace
Thank you for your attention!