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Copyright 2006 John Wiley & Sons, Inc. Beni Asllani
University of Tennessee at Chattanooga
Lean Production
Operations Management - 5th Edition
Roberta Russell & Bernard W. Taylor, III
Copyright 2006 John Wiley & Sons, Inc. 15-2
Lecture Outline
w Basic Elements of Lean Productionw Benefits of Lean Productionw Implementing Lean Productionw Lean Services
Copyright 2006 John Wiley & Sons, Inc. 15-3
Lean Production
w Doing more with less inventory, fewer workers, less space
w Just-in-time (JIT)n smoothing the flow of material to arrive
just as it is neededn JIT and Lean Production are used
interchangeablyw Muda
n waste, anything other than that which adds value to the product or service
Copyright 2006 John Wiley & Sons, Inc. 15-4
Waste in Operations
Copyright 2006 John Wiley & Sons, Inc. 15-5
Waste in Operations (cont.)
Copyright 2006 John Wiley & Sons, Inc. 15-6
Waste in Operations (cont.)
Copyright 2006 John Wiley & Sons, Inc. 15-7
Basic Elements
1. Flexible resources2. Cellular layouts3. Pull production system4. Kanban production control5. Small lot production6. Quick setups7. Uniform production levels8. Total productive
maintenance9. Supplier networks
Copyright 2006 John Wiley & Sons, Inc. 15-8
Flexible Resources
w Multifunctional workersn perform more than one jobn general-purpose machines perform
several basic functionsw Cycle time
n time required for the worker to complete one pass through the operations assigned
w Takt timen paces production to customer demand
Copyright 2006 John Wiley & Sons, Inc. 15-9
Standard Operating Routine for a Worker
Copyright 2006 John Wiley & Sons, Inc. 15-10
Cellular Layouts
w Manufacturing cellsn comprised of dissimilar machines brought
together to manufacture a family of partsw Cycle time is adjusted to match takt time
by changing worker paths
Copyright 2006 John Wiley & Sons, Inc. 15-11
Cells with Worker Routes
Copyright 2006 John Wiley & Sons, Inc. 15-12
Worker Routes Lengthen as Volume Decreases
Copyright 2006 John Wiley & Sons, Inc. 15-13
Pull System
w Material is pulled through the system when needed
w Reversal of traditional push system where material is pushed according to a schedule
w Forces cooperationw Prevent over and underproductionw While push systems rely on a predetermined
schedule, pull systems rely on customer requests
Copyright 2006 John Wiley & Sons, Inc. 15-14
Kanbans
w Card which indicates standard quantity of production
w Derived from two-bin inventory systemw Maintain discipline of pull productionw Authorize production and movement of
goods
Copyright 2006 John Wiley & Sons, Inc. 15-15
Sample Kanban
Copyright 2006 John Wiley & Sons, Inc. 15-16
Origin of Kanban a) Two-bin inventory system b) Kanban inventory system
Reorder card
Bin 1
Bin 2
Q - R
Kanban
R R
Q = order quantity R = reorder point - demand during lead time
Copyright 2006 John Wiley & Sons, Inc. 15-17
Types of Kanban
w Production kanbann authorizes production of
goodsw Withdrawal kanban
n authorizes movement of goods
w Kanban squaren a marked area designated
to hold items
w Signal kanbann a triangular kanban
used to signal production at the previous workstation
w Material kanbann used to order material in
advance of a processw Supplier kanban
n rotates between the factory and suppliers
Copyright 2006 John Wiley & Sons, Inc. 15-18
Copyright 2006 John Wiley & Sons, Inc. 15-19
Copyright 2006 John Wiley & Sons, Inc. 15-20
Copyright 2006 John Wiley & Sons, Inc. 15-21
Determining Number of Kanbans
where
N = number of kanbans or containers d = average demand over some time period L = lead time to replenish an order S = safety stock C = container size
No. of Kanbans = average demand during lead time + safety stock
container size
N = dL + S C
Copyright 2006 John Wiley & Sons, Inc. 15-22
Determining Number of Kanbans: Example
d = 150 bottles per hour L = 30 minutes = 0.5 hours S = 0.10(150 x 0.5) = 7.5 C = 25 bottles
Round up to 4 (to allow some slack) or down to 3 (to force improvement)
N = =
= = 3.3 kanbans or containers
dL + S C
(150 x 0.5) + 7.5 25
75 + 7.5 25
Copyright 2006 John Wiley & Sons, Inc. 15-23
Small Lots
w Require less space and capital investment
w Move processes closer togetherw Make quality problems easier to
detectw Make processes more dependent
on each other
Copyright 2006 John Wiley & Sons, Inc. 15-24
Inventory Hides Problems
Copyright 2006 John Wiley & Sons, Inc. 15-25
Less Inventory Exposes Problems
Copyright 2006 John Wiley & Sons, Inc. 15-26
Components of Lead Time
w Processing timen Reduce number of items or improve efficiency
w Move timen Reduce distances, simplify movements, standardize
routingsw Waiting time
n Better scheduling, sufficient capacityw Setup time
n Generally the biggest bottleneck
Copyright 2006 John Wiley & Sons, Inc. 15-27
Quick Setups
w Internal setupn Can be performed
only when a process is stopped
w External setupn Can be performed
in advance
w SMED Principlesn Separate internal setup from
external setupn Convert internal setup to external
setupn Streamline all aspects of setupn Perform setup activities in
parallel or eliminate them entirely
Copyright 2006 John Wiley & Sons, Inc. 15-28
Common Techniques for Reducing Setup Time
Copyright 2006 John Wiley & Sons, Inc. 15-29
Common Techniques for Reducing Setup Time (cont.)
Copyright 2006 John Wiley & Sons, Inc. 15-30
Common Techniques for Reducing Setup Time (cont.)
Copyright 2006 John Wiley & Sons, Inc. 15-31
Uniform Production Levels
w Result from smoothing production requirements
w Kanban systems can handle +/- 10% demand changes
w Smooth demand across planning horizon
w Mixed-model assembly steadies component production
Copyright 2006 John Wiley & Sons, Inc. 15-32
Mixed-Model Sequencing
Copyright 2006 John Wiley & Sons, Inc. 15-33
Quality at the Source
w Visual controln makes problems visible
w Poka-yokesn prevent defects from
occurringw Kaizen
n a system of continuous improvement; change for the good of all
w Jidokan authority to stop the
production linew Andons
n call lights that signal quality problems
w Under-capacity schedulingn leaves time for planning,
problem solving, and maintenance
Copyright 2006 John Wiley & Sons, Inc. 15-34
Examples of Visual Control
Copyright 2006 John Wiley & Sons, Inc. 15-35
Examples of Visual Control (cont.)
Copyright 2006 John Wiley & Sons, Inc. 15-36
Examples of Visual Control (cont.)
Copyright 2006 John Wiley & Sons, Inc. 15-37
Total Productive Maintenance (TPM)
w Breakdown maintenancen Repairs to make failed machine operational
w Preventive maintenancen System of periodic inspection and
maintenance to keep machines operatingw TPM combines preventive maintenance
and total quality concepts
Copyright 2006 John Wiley & Sons, Inc. 15-38
TPM Requirements
w Design products that can be easily produced on existing machines
w Design machines for easier operation, changeover, maintenance
w Train and retrain workers to operate machinesw Purchase machines that maximize productive
potentialw Design preventive maintenance plan spanning
life of machine
Copyright 2006 John Wiley & Sons, Inc. 15-39
Unneeded equipment, tools, furniture; unneeded items on walls, bulletins; items blocking aisles or stacked in corners; unneeded inventory, supplies, parts; safety hazards Items not in their correct places; correct
places not obvious; aisles, workstations, & equipment locations not indicated; items not put away immediately after use Floors, walls, stairs, equipment, & surfaces
not lines, clean; cleaning materials not easily accessible; labels, signs broken or unclean; other cleaning problems Necessary information not visible; standards
not known; checklists missing; quantities and limits not easily recognizable; items cant be located within 30 seconds Number of workers without 5S training;
number of daily 5S inspections not performed; number of personal items not stored; number of times job aids not available or up-to-date
Keep only what you need
A place for everything and everything in its place Cleaning, and
looking for ways to keep clean and organized
Maintaining and monitoring the first three categories Sticking to the rules
Seiri (sort)
Seiton (set in order)
Seisou (shine)
Seiketsu (standardize)
Shisuke (sustain)
5S Scan Goal Eliminate or Correct
Copyright 2006 John Wiley & Sons, Inc. 15-40
Supplier Networks
w Long-term supplier contractsw Synchronized productionw Supplier certificationw Mixed loads and frequent deliveriesw Precise delivery schedulesw Standardized, sequenced deliveryw Locating in close proximity to the customer
Copyright 2006 John Wiley & Sons, Inc. 15-41
Benefits of Lean Production
w Reduced inventoryw Improved qualityw Lower costsw Reduced space requirementsw Shorter lead timew Increased productivity
Copyright 2006 John Wiley & Sons, Inc. 15-42
Benefits of Lean Production (cont.)
w Greater flexibilityw Better relations with suppliersw Simplified scheduling and control activitiesw Increased capacityw Better use of human resourcesw More product variety
Copyright 2006 John Wiley & Sons, Inc. 15-43
Implementing Lean Production
w Use lean production to finely tune an operating system
w Somewhat different in USA than Japanw Lean production is still evolvingw Lean production isnt for everyone
Copyright 2006 John Wiley & Sons, Inc. 15-44
Lean Services
w Basic elements of lean production apply equally to services
w Most prevalent applicationsn lean retailingn lean bankingn lean health care
Copyright 2006 John Wiley & Sons, Inc. 15-45
Copyright 2006 John Wiley & Sons, Inc. All rights reserved. Reproduction or translation of this work beyond that permitted in section 117 of the 1976 United States Copyright Act without express permission of the copyright owner is unlawful. Request for further information should be addressed to the Permission Department, John Wiley & Sons, Inc. The purchaser may make back-up copies for his/her own use only and not for distribution or resale. The Publisher assumes no responsibility for errors, omissions, or damages caused by the use of these programs or from the use of the information herein.