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LEAN system. Supporting goals. A balanced system, smooth, rapid flow of materials and/or work Supporting goals: Eliminate disruption Make the system flexible eliminate waste, especially exess inventory. Value. That customer is willing to pay - PowerPoint PPT Presentation
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LEAN system
Supporting goals
• A balanced system, smooth, rapid flow of materials and/or work
• Supporting goals:– Eliminate disruption– Make the system
flexible– eliminate waste,
especially exess inventory
Value• That customer is
willing to pay• That changes products
color, function, shape, other attributes so that the product is getting closer to the customers requirements
• That we do right at first time
Wastes• Those processes which directly do not create
value for customers (muda, mura, muri) :– that are not necessary, and must be eliminated– That are necessary, because these are
supporting value-add processes, cannot be eliminated (like transporting)
• Muda – 7 wastes of lean• Mura – not leveled workflow• Muri – overloading of workers and assets
There are 7 wastes in LEAN (TIMWOOD):
• Inventory • Overproduction • Waiting• Unnecessary
transportation• Processing waste• Inefficient work
methods• Defects
Lean thinking
Operation
Traditional improvement
Lean improvement
Non value-add process
Value-add process
JIT Building Blocks
• Process design
• Product design
• Personnel/organizationalelements
• Manufacturing planning and control
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 storage space
Less rework
Problems are more apparent
Increases product flexibility
Easier to balance operations
Setup time
• reducing changeover time ( because small lots require frequent setups)
• SMED (single minute exchange of die)
–External
–Internal activities.
Manufacturing cells
• 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
• Kaizen – continuous improvement of the system
• Jidoka (Autonomation) – automatic detection of defects during production. It consist two activities:– One for detecting defects
when they occur– Another for stopping
production to correct the cause of defects.
• Poka Yoke safeguards built into the process to reduce the possibility of errors.
Work flexibility• Overall goal of lean is to achieve the ability to process mix of
products in a smooth flow.• One potential obstacle is bottlenecks, which occur when portions of
the system become overloaded. Because of – The absence of workers cross trained workers– Not leveled workflow use takt time
• 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 cycle 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 storage
• Inventory storage is a waste, • a buffer which can cover up problems, partly
because inventory makes them seem less serious.
Product Design• Standard parts – fewer parts to deal with lower training costs
• Modular design – easy to satisfy different needs
• Highly capable production systems – quality is designed into the product and the production process
• Concurrentengineering
Personnel/Organizational Elements
• Workers as assets
• Cross-trained workers
• Continuous improvement
• Cost accounting
• Leadership/project management
Manufacturing Planning and Control
• Level loading
• Pull systems
• Visual systems
• Close vendor relationships
• Reduced transaction processing
• Preventive maintenance
Mixed model sequencing
• the sequence (on the base of setup time and setup cost – let it be now A,C,B)
• how many times the sequence should be repeated (determine the smallest integer)
• how many units to produce
Model Daily quantity Units per cycle
A 10 10/5=2
B 15 15/5=3
C 5 5/5=1
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
Visual system
• Kanban- a manual system responds to signals of the need for delivery of parts and materials (both to the factory and between the workstation)– Production kanban– Conveyance kanban
Traditional Supplier NetworkTraditional Supplier Network
BuyerBuyer
SupplierSupplierSupplierSupplier SupplierSupplier SupplierSupplier
SupplierSupplier
SupplierSupplierSupplierSupplier
Figure 12.4a
Tiered Supplier NetworkTiered Supplier NetworkFigure 12.4b
SupplierSupplier
SupplierSupplier
SupplierSupplier
SupplierSupplierSupplierSupplier SupplierSupplier
BuyerBuyer
SupplierSupplierFirst Tier SupplierFirst Tier Supplier
Second Tier SupplierSecond Tier Supplier
Third Tier SupplierThird Tier Supplier
Comparison of JIT and Traditional
Factor Traditional JIT
Inventory Much to offset forecast errors, late deliveries
Minimal necessary to operate
Deliveries Few, large Many, small
Lot sizes Large Small
Setup; runs Few, long runs Many, short runs
Vendors Long-term relationships are unusual
Partners
Workers Necessary to do the work
Assets
Table 12.3
Preventive maintenance
• Total Productive Maintenance – operators responsible for the equipments they use
• Housekeeping – 5S– Sort– Straighten– Sweep– Standardize– Self-discipline
Thank you for your attention!