pom - chapter 12 lean production 190111

POM/sem2/divB/AA/Ch12 1

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©The McGraw-Hill Companies, Inc., 2006

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McGraw-Hill/Irwin

Chapter 12Chapter 12

Lean ProductionLean Production


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• Lean Production Defined

• The Toyota Production System

• Lean Implementation Requirements

• Lean Services

OBJECTIVES


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Lean ProductionLean Production

• Lean Production can be defined as an integrated set of activities designed to achieve high-volume production using minimal inventories (raw materials, work in process, and finished goods)

• Lean Production also involves the elimination of waste in production effort

• Lean Production also involves the timing of production resources (i.e., parts arrive at the next workstation “just in time”)


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Pull SystemPull System

Customers

Sub

Sub

Fab

Fab

Fab

Fab

Vendor

Vendor

Vendor

Vendor

Final Assembly

Here the customer starts the process, pulling an inventory item from Final Assembly…

Here the customer starts the process, pulling an inventory item from Final Assembly…

Then sub-assembly work is pulled forward by that demand…

Then sub-assembly work is pulled forward by that demand…

The process continues throughout the entire production process and supply chain

The process continues throughout the entire production process and supply chain


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Features of Lean ProductionFeatures of Lean Production

• Management philosophy• “Pull” system though the plant

WHAT IT IS

• Employee participation• Industrial engineering/basics• Continuing improvement• Total quality control• Small lot sizes

WHAT IT REQUIRES

• Attacks waste• Exposes problems and bottlenecks• Achieves streamlined production

WHAT IT DOES

• Stable environment

WHAT IT ASSUMES


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The Toyota Production SystemThe Toyota Production System

•Based on two philosophies:

– 1. Elimination of waste

– 2. Respect for people


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Elimination of WasteElimination of Waste

1. Focused factory networks

2. Group technology

3. Quality at the source

4. JIT production

5. Uniform plant loading

6. Kanban production control system

7. Minimized setup times


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Minimizing Waste: Minimizing Waste: Focused Factory Focused Factory

NetworksNetworks

CoordinationSystem Integration

These are small specialized plants that limit the range of products produced (sometimes only one type of product for an entire facility)

These are small specialized plants that limit the range of products produced (sometimes only one type of product for an entire facility)

Some plants in Japan have as few as 30 and as many as 1000 employees

Some plants in Japan have as few as 30 and as many as 1000 employees


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Minimizing Waste: Minimizing Waste: Group TechnologyGroup Technology (Part 1) (Part 1)

• Using Departmental Specialization for plant layout can cause a lot of unnecessary material movement

• Using Departmental Specialization for plant layout can cause a lot of unnecessary material movement

Saw Saw

Lathe PressPress

Grinder

LatheLathe

Saw

Press

Heat Treat

Grinder

Note how the flow lines are going back and forthNote how the flow lines are going back and forth


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Minimizing Waste: Minimizing Waste: Group Technology (Part 2)Group Technology (Part 2)

• Revising by using Group Technology Cells can reduce movement and improve product flow

• Revising by using Group Technology Cells can reduce movement and improve product flow

Press

Lathe

Grinder

Grinder

A

2

BSaw

Heat Treat

LatheSaw Lathe

PressLathe

1


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Minimizing Waste: Minimizing Waste: Uniform Plant Loading (heijunka)Uniform Plant Loading (heijunka)

Not uniform Jan. Units Feb. Units Mar. Units Total

1,200 3,500 4,300 9,000

Uniform Jan. Units Feb. Units Mar. Units Total

3,000 3,000 3,000 9,000

Suppose we operate a production plant that produces a single product. The schedule of production for this product could be accomplished using either of the two plant loading schedules below.

Suppose we operate a production plant that produces a single product. The schedule of production for this product could be accomplished using either of the two plant loading schedules below.

How does the uniform loading help save labor costs?How does the uniform loading help save labor costs?

or


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Minimizing Waste: Inventory Minimizing Waste: Inventory Hides ProblemsHides Problems

Work in

process

queues

(banks)

Change

orders

Engineering design

redundancies

Vendor

delinquencies

Scrap

Design

backlogs

Machine

downtime

Decision

backlogsInspection

backlogs

Paperwork

backlog

Example: By identifying defective items from a vendor early in the production process the downstream work is saved

Example: By identifying defective work by employees upstream, the downstream work is saved


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Minimizing Waste: Kanban Production Minimizing Waste: Kanban Production Control SystemsControl Systems

Storage Part A

Storage Part AMachine

Center Assembly Line

Material Flow

Card (signal) Flow

Withdrawal kanban

Once the Production kanban is received, the Machine Center produces a unit to replace the one taken by the Assembly Line people in the first place

This puts the system back were it was before the item was pulled

The process begins by the Assembly Line people pulling Part A from Storage

Production kanban


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Determining the Number of Determining the Number of Kanbans NeededKanbans Needed

• Setting up a kanban system requires determining the number of kanbans cards (or containers) needed

• Each container represents the minimum production lot size

• An accurate estimate of the lead time required to produce a container is key to determining how many kanbans are required


16The Number of Kanban Card The Number of Kanban Card SetsSets

C

SDL

k

)(1

container theof Size

stockSafety timelead during demand Expected

C

SDL

k

)(1



k = Number of kanban card sets (a set is a card)D = Average number of units demanded over some time periodL = lead time to replenish an order (same units of time as demand)S = Safety stock expressed as a percentage of demand during leadtimeC = Container size


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Example of Kanban Card Example of Kanban Card Determination: Problem DataDetermination: Problem Data

• A switch assembly is assembled in batches of 4 units from an “upstream” assembly area and delivered in a special container to a “downstream” control-panel assembly operation

• The control-panel assembly area requires 5 switch assemblies per hour

• The switch assembly area can produce a container of switch assemblies in 2 hours

• Safety stock has been set at 10% of needed inventory


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Example of Kanban Card Example of Kanban Card Determination: CalculationsDetermination: Calculations

3or ,75.24

5(2)(1.1))(1



C

SDL

k

3or ,75.24

5(2)(1.1))(1



C

SDL

k

Always round up!


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Respect for PeopleRespect for People

• Level payrolls

• Cooperative employee unions

• Subcontractor networks

• Bottom-round management style

• Quality circles (Small Group Involvement Activities or SGIA’s)


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Toyota Production System’s Four RulesToyota Production System’s Four Rules

1. All work shall be highly specified as to content, sequence, timing, and outcome

2. Every customer-supplier connection must be direct, and there must be an unambiguous yes-or-no way to send requests and receive responses

3. The pathway for every product and service must be simple and direct

4. Any improvement must be made in accordance with the scientific method, under the guidance of a teacher, at the lowest possible level in the organization


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Lean Implementation Lean Implementation Requirements: Design Flow Requirements: Design Flow

ProcessProcess

• Link operations

• Balance workstation capacities

• Redesign layout for flow

• Emphasize preventive maintenance

• Reduce lot sizes

• Reduce setup/changeover time


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Lean Implementation Lean Implementation Requirements: Total Quality Requirements: Total Quality

ControlControl

• Worker responsibility

• Measure SQC

• Enforce compliance

• Fail-safe methods

• Automatic inspection


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Lean Implementation Lean Implementation Requirements: Stabilize ScheduleRequirements: Stabilize Schedule

• Level schedule

• Underutilize capacity

• Establish freeze windows


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Lean Implementation Lean Implementation Requirements: Kanban-PullRequirements: Kanban-Pull

• Demand pull

• Backflush

• Reduce lot sizes


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Lean Implementation Lean Implementation Requirements: Work with VendorsRequirements: Work with Vendors• Reduce lead times

• Frequent deliveries

• Project usage requirements

• Quality expectations


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Lean Implementation Lean Implementation Requirements: Reduce Inventory Requirements: Reduce Inventory

MoreMore

• Look for other areas

• Stores

• Transit

• Carousels

• Conveyors


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Lean Implementation Requirements: Lean Implementation Requirements: Improve Product DesignImprove Product Design

• Standard product configuration

• Standardize and reduce number of parts

• Process design with product design

• Quality expectations


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Lean Implementation Requirements: Lean Implementation Requirements: Concurrently Solve ProblemsConcurrently Solve Problems

• Root cause • Solve permanently

• Team approach

• Line and specialist responsibility

• Continual education


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Lean Implementation Requirements: Lean Implementation Requirements: Measure PerformanceMeasure Performance

•Emphasize improvement

•Track trends


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Lean in Services (Examples)Lean in Services (Examples)

• Organize Problem-Solving Groups

• Upgrade Housekeeping

• Upgrade Quality

• Clarify Process Flows

• Revise Equipment and Process Technologies


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Lean in Services (Examples)Lean in Services (Examples)

• Level the Facility Load

• Eliminate Unnecessary Activities

• Reorganize Physical Configuration

• Introduce Demand-Pull Scheduling

• Develop Supplier Networks

pom - chapter 12 lean production 190111

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