Transcript Lean Production

Chapter 15
Lean Production
Operations Management - 5th Edition
Roberta Russell & Bernard W. Taylor, III
Copyright 2006 John Wiley & Sons, Inc.
Beni Asllani
University of Tennessee at Chattanooga
Lecture Outline
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Basic Elements of Lean Production
Benefits of Lean Production
Implementing Lean Production
Lean Services
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Lean Production
 Doing more with less inventory, fewer
workers, less space
 Just-in-time (JIT)
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smoothing the flow of material to arrive
just as it is needed
“JIT” and “Lean Production” are used
interchangeably
 Muda
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waste, anything other than that which
adds value to the product or service
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Waste in Operations
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Waste in Operations (cont.)
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Waste in Operations (cont.)
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Basic Elements
1.
2.
3.
4.
5.
6.
7.
8.
9.
Flexible resources
Cellular layouts
Pull production system
Kanban production control
Small lot production
Quick setups
Uniform production levels
Total productive
maintenance
Supplier networks
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Flexible Resources
 Multifunctional workers
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perform more than one job
general-purpose machines perform
several basic functions
 Cycle time
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time required for the worker to complete
one pass through the operations
assigned
 Takt time
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paces production to customer demand
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Standard Operating
Routine for a Worker
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Cellular Layouts
 Manufacturing cells
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comprised of dissimilar machines brought
together to manufacture a family of parts
 Cycle time is adjusted to match takt time
by changing worker paths
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Cells with Worker Routes
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Worker Routes Lengthen as
Volume Decreases
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Inventory Hides Problems
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Less Inventory Exposes Problems
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Cost Impact of Inventory
 High inventory  high inventory holding costs
 High inventory hides problems, and the company
pays for the cost of the problems
 In manufacturing, high inventory requires large lot
sizes
 Long manufacturing lead times
 Harder to meet changing customer demand
 Delays in introducing new or improved products
Reducing Inventory
Kanban Pull System
 Production kanban: authorization to make a container
of parts
 No production can be done without a production
kanban and an empty container
 Withdrawal kanban: authorization to get a container
of parts for use in the next process step
 Work in process (WIP) inventory
 WIP < (number of kanbans)(lot size)
 Lot size = number of parts of a certain type
produced at one time
Reducing Inventory
Kanban Pull System
Pull System
 Material is pulled through the system when
needed
 Reversal of traditional push system where
material is pushed according to a schedule
 Forces cooperation
 Prevent over and underproduction
 While push systems rely on a predetermined
schedule, pull systems rely on customer
requirements
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Reducing Inventory
Small Lot Sizes and Quick Setups
 Benefits of small lot sizes
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Shorter manufacturing lead time  Faster response to
changes in customer demand
Lower inventory and inventory holding costs
 Small lot sizes require more setups
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Setups must be done more quickly and at lower costs. This
is necessary
 To ensure adequate capacity
 To control setup costs
 To avoid production delays
Uniform Production Levels
 Result from smoothing production
requirements
 Kanban systems can handle +/- 10%
demand changes
 Smooth demand across planning
horizon
 Mixed-model assembly steadies
component production
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Mixed-Model Sequencing
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Quality at the Source
 Visual control
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makes problems visible
 Poka-yokes
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prevent defects from
occurring
 Kaizen
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a system of continuous
improvement; “change for
the good of all”
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 Jidoka
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authority to stop the
production line
 Andons
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call lights that signal
quality problems
 Under-capacity
scheduling
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leaves time for planning,
problem solving, and
maintenance
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Examples of Visual Control
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Examples of Visual Control (2)
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Examples of Visual Control (3)
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Total Productive
Maintenance (TPM)
 Breakdown maintenance
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Repairs to make failed machine operational
 Preventive maintenance
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System of periodic inspection and
maintenance to keep machines operating
 TPM combines preventive maintenance
and total quality management concepts
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5S Scan
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Seiri
(sort)
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Seiton
(set in order)
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Seisou
(shine)
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Seiketsu
(standardize)
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Shisuke
(sustain)
Goal
 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
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Eliminate or Correct
 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 can’t 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
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Supplier Networks
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Long-term supplier contracts
Synchronized production with suppliers
Supplier certification
Mixed loads and frequent deliveries
Precise delivery schedules
Standardized, sequenced delivery
Locating in close proximity to the customer
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Benefits of Lean
Production
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Reduced inventory
Improved quality
Lower costs
Reduced space requirements
Shorter lead time
Increased productivity
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Benefits of Lean Production (2)
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Greater flexibility
Better relations with suppliers
Simplified scheduling
Increased capacity
Better use of human resources
More product variety than repetitive
manufacturing
 More efficient than intermittent manufacturing
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Limitations of lean production
 If the company makes only a small number of
high-volume items, then mass production or
continuous manufacturing will be more efficient
 Lean production does not work well when
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many low-volume items make scheduling hard
total demand is seasonal or highly variable
the company must accommodate large rush orders
the company is small and cannot afford enough
equipment for cellular manufacturing
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Lean Services
 Basic elements of lean production
apply equally to services
 Most prevalent applications
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lean retailing
lean banking
lean health care
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Copyright 2006 John Wiley & Sons, Inc.
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