copyright © 2014 by mcgraw-hill education (asia). all rights reserved. 15 jit and lean operations
TRANSCRIPT
Copyright © 2014 by McGraw-Hill Education (Asia). All rights reserved.
1515
JIT andLean Operations
15-2
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.
15-3
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”
15-4
Toyota ApproachToyota Approach
Muda
Kanban
Pull System
Heijunka
Kaizen
Jidoka
Poka-yoke
Team concept
15-5
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.
15-6
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
15-7
Supporting GoalsSupporting Goals
Eliminate disruptions
Make system flexible
Eliminate waste, especially excess inventory
15-8
Sources of WasteSources of Waste
Overproduction
Waiting time
Unnecessary transportation
Processing waste
Inefficient work methods
Product defects
Copyright 2009 John Wiley & Sons,
Inc.
16-9
Waste in OperationsWaste in Operations
Copyright 2009 John Wiley & Sons,
Inc.
16-10
Waste in Operations (cont.)Waste in Operations (cont.)
Copyright 2009 John Wiley & Sons,
Inc.
16-11
Waste in Operations (cont.)Waste in Operations (cont.)
15-12
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
16-18Copyright 2009 John Wiley & Sons, Inc.
Inventory Hides ProblemsInventory Hides Problems
Small Lot sizesSmall Lot sizes
16-19Copyright 2009 John Wiley & Sons, Inc.
Less Inventory Exposes ProblemsLess Inventory Exposes Problems
15-20
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
15-21
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
Copyright 2009 John Wiley & Sons,
Inc.
16-22
Common Techniques for Common Techniques for Reducing Setup TimeReducing Setup Time
Copyright 2009 John Wiley & Sons,
Inc.
16-23
Common Techniques for Common Techniques for Reducing Setup Time (cont.)Reducing Setup Time (cont.)
Copyright 2009 John Wiley & Sons,
Inc.
16-24
Common Techniques for Common Techniques for Reducing Setup Time (cont.)Reducing Setup Time (cont.)
15-30
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
16-31Copyright 2009 John Wiley & Sons, Inc.
15-32
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
15-33
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
Copyright 2009 John Wiley & Sons,
Inc.
16-34
Sample KanbanSample Kanban
Copyright 2009 John Wiley & Sons,
Inc.
16-35
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
Q - R
KanbanKanban
RR
QQ = order quantity = order quantity
RR = reorder point - demand during lead time = reorder point - demand during lead time
15-36
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
16-37Copyright 2009 John Wiley & Sons, Inc.
16-38Copyright 2009 John Wiley & Sons, Inc.
Types of KanbanTypes of Kanban
16-39Copyright 2009 John Wiley & Sons, Inc.
Types of KanbanTypes of Kanban
Copyright 2009 John Wiley & Sons,
Inc.
16-40
Examples of Visual ControlExamples of Visual Control
Copyright 2009 John Wiley & Sons,
Inc.
16-41
Examples of Visual Control (cont.)Examples of Visual Control (cont.)
Copyright 2009 John Wiley & Sons,
Inc.
16-42
Examples of Visual Control (cont.)Examples of Visual Control (cont.)
15-43
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
15-44
Traditional Supplier NetworkTraditional Supplier Network
BuyerBuyer
SupplierSupplierSupplierSupplier SupplierSupplier SupplierSupplier
SupplierSupplier
SupplierSupplierSupplierSupplier
Figure 15.4A
15-45
Tiered Supplier NetworkTiered Supplier NetworkFigure 15.4B
SupplierSupplier
SupplierSupplier
SupplierSupplier
SupplierSupplierSupplierSupplier SupplierSupplier
BuyerBuyer
SupplierSupplierFirst Tier SupplierFirst Tier Supplier
Second Tier SupplierSecond Tier Supplier
Third Tier SupplierThird Tier Supplier
15-46
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.
15-47
Housekeeping Five S’sHousekeeping Five S’s
1. Sort
2. Straighten
3. Sweep
4. Standardize
5. Self-discipline
15-48
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
15-49
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
15-50
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
15-51
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?
15-52
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
15-53
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
15-54
JIT II: a supplier representative works right in the company’s plant, making sure there is an appropriate supply on hand.
JIT IIJIT II
15-55
Summary of Benefits of JITSummary of Benefits of JIT
Reduced inventory levels
High quality
Flexibility
Reduced lead times
Increased productivity
15-56
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