Copyright © 2014 by McGraw-Hill Education (Asia). All rights reserved. 15 JIT and Lean Operations.

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JIT andLean Operations

Learning ObjectivesLearning Objectives

Explain what is meant by the term lean operations system.

List each of the goals of JIT and explain its importance.

List and briefly describe the building blocks of JIT. List the benefits of the JIT system. Outline the considerations important in converting

a traditional mode of operations to a JIT system. List some of the obstacles that might be

encountered when converting to a JIT system.

JIT/Lean ProductionJIT/Lean Production

Just-in-time (JIT): A highly coordinated processing system in which goods move through the system, and services are performed, just as they are needed,

JIT lean production

JIT pull (demand) system

JIT operates with very little “fat”

Toyota ApproachToyota Approach

Kanban

Pull System

Heijunka

Kaizen

Jidoka

Poka-yoke

Team concept

Goal of JITGoal of JIT

The ultimate goal of JIT is a balanced system.

Achieves a smooth, rapid flow of materials through the system.

Makes processing time as short as possible by using resources in best possible way.

Summary JIT Goals and Building BlocksSummary JIT Goals and Building BlocksFigure 15.1

Product Design

ProcessDesign

PersonnelElements

Manufactur-ing Planning

Eliminate disruptions

Make the system flexible Eliminate waste

Abalancedrapid flow

UltimateGoal

SupportingGoals

Building Blocks

Supporting GoalsSupporting Goals

Eliminate disruptions

Make system flexible

Eliminate waste, especially excess inventory

Sources of WasteSources of Waste

Overproduction

Waiting time

Unnecessary transportation

Processing waste

Inefficient work methods

Product defects

Waste in OperationsWaste in Operations

Waste in Operations (cont.)Waste in Operations (cont.)

Kaizen PhilosophyKaizen Philosophy

Waste is the enemy Improvement should be done gradually and

continuously Everyone should be involved Built on a cheap strategy Can be applied anywhere

Small Lot sizesSmall Lot sizes

Inventory Hides ProblemsInventory Hides Problems

Small Lot sizesSmall Lot sizes

Less Inventory Exposes ProblemsLess Inventory Exposes Problems

Benefits of Small Lot SizesBenefits of Small Lot Sizes

Reduces inventory

Less storage space

Less rework

Problems are more apparent

Increases product flexibility

Easier to balance operations

Setup Time ReductionSetup Time Reduction

Single-minute exchange of die (SMED): A system for reducing changeover time

Categorize changeover activities Internal – activities that can only be done while

machine is stopped External – activities that do not require stopping

the machine

Common Techniques for Common Techniques for Reducing Setup TimeReducing Setup Time

Common Techniques for Common Techniques for Reducing Setup Time (cont.)Reducing Setup Time (cont.)

Manufacturing Planning and ControlManufacturing Planning and Control

Level loading

Pull systems

Visual systems

Limited work-in-process (WIP)

Close vendor relationships

Reduced transaction processing

Preventive maintenance

Level LoadingLevel Loading

Pull/Push SystemsPull/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 SystemKanban 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 production control system

Authority to pull, or produce comes from a downstream process

Sample KanbanSample Kanban

Origin of KanbanOrigin of Kanban

a) Two-bin inventory systema) Two-bin inventory system b) Kanban inventory systemb) Kanban inventory system

Reorder Reorder cardcard

Bin 1Bin 1

Bin 2Bin 2

KanbanKanban

QQ = order quantity = order quantity

RR = reorder point - demand during lead time = reorder point - demand during lead time

Kanban FormulaKanban Formula

N = DT(1+X)C

N = Total number of containersD = Planned usage rate of using work centerT = Average waiting time for replenishment of parts plus average production time for a container of partsX = Policy variable set by management to reflect possible inefficiency in the systemC = Capacity of a standard container

Types of KanbanTypes of Kanban

Examples of Visual ControlExamples of Visual Control

Examples of Visual Control (cont.)Examples of Visual Control (cont.)

Limited Work-in-Process (WIP)Limited Work-in-Process (WIP)

Benefits Lower carrying costs Increased flexibility Aids scheduling Saves cost of rework and scrap

Two general approaches Kanban – focuses on individual work stations Constant work-in-process (CONWIP) – focuses

on the system as a whole

Traditional Supplier NetworkTraditional Supplier Network

BuyerBuyer

SupplierSupplierSupplierSupplier SupplierSupplier SupplierSupplier

SupplierSupplier

SupplierSupplierSupplierSupplier

Figure 15.4A

Tiered Supplier NetworkTiered Supplier NetworkFigure 15.4B

SupplierSupplier

SupplierSupplierSupplierSupplier SupplierSupplier

BuyerBuyer

SupplierSupplierFirst Tier SupplierFirst Tier Supplier

Second Tier SupplierSecond Tier Supplier

Third Tier SupplierThird Tier Supplier

Preventive Maintenance and Preventive Maintenance and HousekeepingHousekeeping

Preventative maintenance: Maintaining equipment in good condition and replacing parts that have a tendency to fail before they actually fail.

Housekeeping: Maintaining a workplace that is clean and free of unnecessary materials.

Housekeeping Five S’sHousekeeping Five S’s

1. Sort

2. Straighten

3. Sweep

4. Standardize

5. Self-discipline

Benefits of Five S’sBenefits of Five S’s

1. Increased productivity

2. Improved employee morale

3. Decreased risk of accidents

4. Improved appearance for visitors

Comparison of JIT and Traditional SystemsComparison of JIT and Traditional Systems

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 15.3

Transitioning to a JIT SystemTransitioning to a JIT System

Get top management commitment

Decide which parts need most effort

Obtain support of workers

Start by trying to reduce setup times

Gradually convert operations

Convert suppliers to JIT

Prepare for obstacles

Obstacles to ConversionObstacles to Conversion

Management may not be committed

Workers/management may not be cooperative

Difficult to change company culture

Suppliers may resist Why?

Why Suppliers Resist JITWhy Suppliers Resist JIT

Unwilling to commit resources Uneasy about long-term commitments Frequent, small deliveries may be difficult Burden of quality control shifts to supplier Frequent engineering changes may cause

JIT changes

JIT in ServicesJIT in Services

The basic goal of the demand flow technology in the service organization is to provide optimum response to the customer with the highest quality service and lowest possible cost. Eliminate disruptions Make system flexible Reduce setup and lead times Eliminate waste Minimize WIP Simplify the process

JIT II: a supplier representative works right in the company’s plant, making sure there is an appropriate supply on hand.

JIT IIJIT II

Summary of Benefits of JITSummary of Benefits of JIT

Reduced inventory levels

High quality

Flexibility

Reduced lead times

Increased productivity

Increased equipment utilization

Reduced scrap and rework

Reduced space requirements

Pressure for good vendor relationships

Reduced need for indirect labor

Summary of Benefits of JITSummary of Benefits of JIT

Copyright © 2014 by McGraw-Hill Education (Asia). All rights reserved. 15 JIT and Lean Operations.

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