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V. D. Shikhare

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The McGraw-Hill Companies, Inc., 2006

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McGraw-Hill/Irwin

Lean Production(JUST IN TIME)

Session 10

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Lean Production Defined

The Toyota Production System

Lean Implementation

Requirements

Lean Services

OBJECTIVES

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Lean Production Lean Production can be defined as an

integrated set of activities designed toachieve high-volume production usingminimal 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 arriveat the next workstation just in time)

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Characteristics of Lean Systems

Pull Method of work flow

Quality at the source

Small Lot sizes

Uniform Workstation Loads

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Characteristics of Lean Systems

Standardized components and

work methods

Close supplier ties

Flexible workforce

Line Flows

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Characteristics of Lean Systems

Automation

Five S

Preventive Maintenance

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Pull 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

Then sub-

assembly work is

pulled forward by

that demand

The process continues

throughout the entire

production process and

supply chain

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Features 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 SystemBased on two philosophies:

1. Elimination of waste

2. Respect for people

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11Toyota Production Systems FourRules1. All work shall be highly specified as to content,

sequence, timing, and outcome

2. Every customer-supplier connection must bedirect, and there must be an unambiguous yes-

or-no way to send requests and receiveresponses

3. The pathway for every product and service mustbe simple and direct

4. Any improvement must be made in accordancewith the scientific method, under the guidanceof a teacher, at the lowest possible level in theorganization

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12Respect for People Level payrolls

Cooperative employee unions

Subcontractor networks

Quality circles (Small GroupInvolvement Activities or SGIAs)

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13Elimination of Waste1. Focused factory networks2. Group technology

3. Quality at the source

4. JIT production

5. Uniform plant loading

6. Kanban production controlsystem

7. Minimized setup times

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Minimizing Waste:Focused FactoryNetworks

CoordinationSystem Integration

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

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Minimizing Waste: Group Technology (Part 1) 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 forth

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Minimizing Waste:Group Technology (Part 2) 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: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 singleproduct. 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?

or

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Minimizing Waste: InventoryHides Problems

Work in

process

queues

(banks)

Changeorders

Engineering design

redundancies

Vendor

delinquencies

Scrap

Design

backlogs

Machine

downtime

Decision

backlogs

Inspection

backlogs

Paperwork

backlog

Example: Byidentifying defective

items from a vendor

early in the

production process

the downstream work

is saved

Example: Byidentifying defective

work by employees

upstream, the

downstream work is

saved

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Minimizing Waste: Kanban ProductionControl Systems

Storage

Part A

Storage

Part AMachine

CenterAssembly

Line

Material Flow

Card (signal) Flow

Withdrawal

kanban

Once the Production kanban isreceived, the Machine Center

produces a unit to replace the

one taken by the Assembly Line

people in the first place

This puts the

system backwhere 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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20Determining the Number ofKanbans NeededSetting up a kanban system requires

determining the number of kanbanscards (or containers) needed

Each container represents the minimumproduction lot size

An accurate estimate of the lead time

required to produce a container is keyto determining how many kanbans arerequired

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The Number of Kanban Card Sets

C

SDL

k

)(1

containertheofSize

stockSafetytimeleadduringdemandExpected

k =Number of kanban card sets (a set is a card)D = Average number of units demanded over some timeperiod

L = lead time to replenish an order (same units of time asdemand)

S = Safety stock expressed as a percentage of demandduring lead time

C = Container size

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Example of Kanban CardDetermination: Problem Data A switch assembly is assembled in batches of

4 units from an upstream assembly areaand delivered in a special container to adownstream control-panel assembly

operation

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

The switch assembly area can produce acontainer of switch assemblies in 2 hours

Safety stock has been set at 10% of neededinventory

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Example of Kanban CardDetermination: Calculations

3or,75.2

4

5(2)(1.1))(1

containertheofSize

stockSafetytimeleadduringdemandExpected

C

SDL

k

Always round up!

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Lean Implementation Requirements:Design Flow Process Link operations

Balance workstation capacities

Redesign layout for flow

Emphasize preventive maintenance

Reduce lot sizesReduce setup/changeover time

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Lean Implementation Requirements:Total Quality Control

Worker responsibility

Measure SQC

Enforce compliance

Fail-safe methods

Automatic inspection

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Lean Implementation Requirements:Stabilize Schedule

Level schedule

Underutilize capacity

Establish freeze windows

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Lean ImplementationRequirements: Kanban-Pull

Demand pull

Backflush

Reduce lot sizes

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Lean Implementation Requirements:Work with Vendors

Reduce lead times

Frequent deliveries

Project usage requirements

Quality expectations

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Lean Implementation Requirements:Reduce Inventory More Look for other areas

Stores

Transit

Carousels

Conveyors

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Lean Implementation Requirements:Improve Product Design Standard product configuration

Standardize and reduce number ofparts

Process design with product design

Quality expectations

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Lean Implementation Requirements:Concurrently Solve ProblemsRoot cause

Solve permanently

Team approach

Line and specialist responsibility

Continual education

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Lean Implementation Requirements:Measure Performance

Emphasize improvementTrack trends

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Lean in Services (Examples)Organize Problem-Solving Groups

Upgrade Housekeeping

Upgrade Quality

Clarify Process Flows

Revise Equipment and ProcessTechnologies

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Lean in Services (Examples)Level the Facility Load

Eliminate Unnecessary Activities

Reorganize Physical Configuration

Introduce Demand-Pull Scheduling

Develop Supplier Networks

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Thank You