Chapter 1 Lean Systems

7/28/2019 Chapter 1 Lean Systems

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Lean Production

SystemsCopyright 2013 Pearson Education, Inc. publishing as Prentice Hall 08- 01


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Systems

What is a Lean System?

Lean Systems

Operations systems that

maximize the valueadded by each of a

companys activities by

removing waste and

delays from them.

08-02Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall


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Eight Types of Waste or Muda

1. Overproduction(Makingproduct before it is needed)

2. Inappropriate Processing(Using expensive equipment when

simple machines would suffice)

3. Waiting (Wasted time whenproduct is not being processed)

4. Transportation (Excessivehandling of product)

5. Motion (Unnecessary effort)

6. Inventory(Excess

Inventory)

7. Defects (Result in rework &scrap. Add wasteful costs)

8. Underutilization of

Employees (Failure tolearn from employees)

Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall 08 - 03


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Continuous Improvement KaizenExcess capacity or inventory hides underlying

problems with the processes

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Lean Systems

Supply Chain Considerations

Close Supplier Ties

Look for ways to improve efficiency and reduce inventories

throughout the supplier chain

Small Lot Sizes Single-digit setup (A setup time less than 10 minutes)

Lean systems use lot sizes that are as small as possible


Lean systems help to reveal problems by systematically loweringcapacities or inventories until the problems are exposed. Look for

ways to improve efficiency throughout the supply chain.


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Process Considerations

Pull Method ofWorkflow-Customer demand activates

the production of a good orservice item.

Push Method

Usingforecasts of demand and

producing the item before

the customer orders it.



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Quality at the Source

Defects are caught and corrected

where they are created

Jidoka

Mistake-proofing methods

Poka-Yoke

(minimize human error)



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Uniform Workstation Loads

Takt time (Cycle time matching production rate to sales)

Heijunka

The leveling of production load by both volume and

product mix (same amount made each day)

Mixed-model assembly

(producing a mix of models in smaller lots)

Standardized Components and Work

Methods (Standardization of common components)



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Flexible Workforce

(Perform more than one job)

Automation (A key to low cost operations)

5S(Methodology for wastereduction)

Total Preventative

Maintenance - TPM

(Reduce machine downtime)



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5S



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Toyota Production System

1. All work should be specified as to content,

sequence, timing, and outcome.

2. All customer-supplier connections should bedirect and unambiguous.

3. All pathways should be simple and direct.

4. All improvements should be made under theguidance of a teacher using the scientific

method.



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House of Toyota

Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall 08- 12


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One-Worker, Multiple MachinesFlexibility / Cellular Production



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Group Technology


Jumbled Flows

without GroupTech.

Lines Flows with 3 Group

Technology cells


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What is a Value Stream Mapping?

Value Stream Mapping

A qualitative lean tool for

eliminating waste or mudathat involves a (1) current

state drawing, a (2) future

state drawing and an (3)

implementation plan.

08- 15Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall


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Value Stream Mapping Metrics

Takt Time Cycle time needed to match the rate of production to

the rate of sales or consumption.

Daily availability/Daily Demand

Cycle Time The average time between completed units taking

into account all resources available at a process step.

Processing Time The time to complete one unit.



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What is a Kanban?

Kanban

A Japanese word

meaning card or

visible record that

refers to cards used to

control the flow ofproduction through a

factory

08- 17Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall


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The Kanban System

Receiving postKanban card

for product 1

Kanban card

for product 2

Fabrication cell

O1

O2

O3

O2

Storage

area

Empty containers

Full containers

Assembly line 1

Assembly line 2



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The Kanban System

Storage

area

Empty containers

Full containers

Receiving post Kanban card for

product 1

Kanban card for

product 2

Fabricationcell

O1

O2

O3

O2

Assembly line 1

Assembly line 2



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The Kanban System

Storage

area

Empty containers

Full containers


product 1

Kanban card for

product 2

Fabricationcell

O1

O2

O3

O2

Assembly line 1

Assembly line 2



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The Kanban System

Storage

area

Empty containers

Full containers


product 1

Kanban card for

product 2

Fabrication cell

O1

O2

O3

O2

Assembly line 1

Assembly line 2



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The Kanban System

Storage

area

Empty containers

Full containers


product 1

Kanban card for

product 2

Fabricationcell

O1

O2

O3

O2

Assembly line 1

Assembly line 2



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The Kanban System

Storage

area

Empty containers

Full containers


product 1

Kanban card for

product 2

Fabricationcell

O1

O2

O3

O2

Assembly line 1

Assembly line 2



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The Kanban System

Storage

area

Empty containers

Full containers

Receiving postKanban card for

product 1

Kanban card for

product 2

FabricationcellO1

O2

O3

O2

Assembly line 1

Assembly line 2



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The Kanban System

1. Each container must have a card.

2. Assembly always withdraws from fabrication(pull system).

3. Containers cannot be moved without a kanban.

4. Containers should contain the same number ofparts.

5. Only good parts are passed along.

6. Production should not exceed authorization.



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Number of Containers

Two determinations

1. Number of units to be held by each container

2. Number of containers Littles Law

oAverage work-in-process inventory equals the

average demand rate multiplied by the average

time a unit spends in the manufacturing process



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Other Kanban Signals

Container System

Using the container itself as a signal device.

Works well with containers specifically designed forparts.

Containerless System

Using visual means in lieu of containers as a signal

device.

Examples: a painted square on a workbench = one

unit.



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Organizational Considerations

The Human Costs of Lean Systems (Whencombined with Statistical Process Control, some systems

may make workers feel stressed)

Cooperation and Trust (The workforce andmanagement must be willing to trust each other and

cooperate in order to achieve their goals)

Reward Systems and Labor Classification(Former reward systems and labor contracts may have to be

revamped in order for lean systems to perform effectively)



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Inventory and Scheduling

Schedule Stability (High-volume lean systems cannotrespond quickly to scheduling changes)

Setups (Lean systems use small lot sizes, but thatrequires a large number of setups)

Purchasing and Logistics (Frequent, small shipmentsof materials from suppliers must be arranged in order to

realize large inventory savings)


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Chapter 1 Lean Systems

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