Chapter 16
Lean Systems
Russell and Taylor
Operations and Supply Chain Management,
8th Edition
Lecture Outline
•
•
•
•
•
•
Basic Elements of Lean Production – Slide 4
Implementing Lean Systems – Slide 47
Lean Six Sigma – Slide 49
Value Stream Mapping – Slide 50
Lean and the Environment – Slide 54
Lean Services – Slide 56
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Learning Objectives
• Explain how the basic elements of lean eliminate waste,
create flow and continuously improve operations
• Assess the benefits of lean, as well as the difficulties in
implementing lean systems
• Explain how the complementary concepts of lean and six
sigma work together for process improvement
• Construct and interpret a value stream map
• Create strategies for implementing lean in service
industries
• Use lean concepts and techniques to enhance
environmental initiatives
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Basic Elements of Lean Production
• Doing more with less inventory, fewer workers,
less space
• Just-in-time (JIT)
• smoothing the flow of material to arrive just as it is
needed
• “JIT” and “Lean Production” are used interchangeably
• Muda
• waste, anything other than that which adds value to
product or service
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Waste in Operations
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Waste in Operations
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Waste in Operations
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Elements of Lean Production
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Flexible resources
Cellular layouts
Pull system
Kanbans
Small lots
Quick setups
Uniform production levels
Quality at the source
Total productive
maintenance
Supplier networks
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Flexible Resources
• Multifunctional workers
• perform more than one job
• General-purpose machines perform several
basic functions
• Cycle time
• time required for the worker to complete one pass
through the operations assigned
• Takt time
• paces production to customer demand
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Standard Operating Routine
for a Worker
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Cellular Layouts
• Manufacturing cells
• 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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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 requests
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Kanbans
• Card which indicates standard quantity of
production
• Derived from two-bin inventory system
• Maintain discipline of pull production
• Authorize production and movement of goods
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Sample Kanban
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Origin of Kanban
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Types of Kanban
• Production kanban
– authorizes production of
goods
• Withdrawal kanban
– authorizes movement of
goods
• Kanban square
• Signal kanban
– triangular kanban to
signal production at the
previous workstation
• Material kanban
– to order material in
advance of a process
– a marked area designated
• Supplier kanban
to hold items
– rotates between the
factory and suppliers
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Dual Kanban System
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Other Kanbans
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Other Kanbans
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Determining Number of Kanbans
No. of Kanbans =
average demand during lead time + safety stock
container size
dL + S
N =
C
where
N
d
L
S
C
= number of kanbans or containers
= average demand over some time period
= lead time to replenish an order
= safety stock
= container size
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Determining Number of Kanbans
d
L
S
C
N=
= 150 bottles per hour
= 30 minutes = 0.5 hours
= 0.10 (150 x 0.5) = 7.5
= 25 bottles
dL + S
=
C
© 2014 John Wiley & Sons, Inc. - Russell and Taylor 8e
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Determining Number of Kanbans
d
L
S
C
= 150 bottles per hour
= 30 minutes = 0.5 hours
= 0.10 (150 x 0.5) = 7.5
= 25 bottles
(150 x 0.5) + 7.5
dL + S
N=
=
25
C
75 + 7.5
=
= 3.3 kanbans or containers
25
Round up to 4 (to allow some slack) or
down to 3 (to force improvement)
© 2014 John Wiley & Sons, Inc. - Russell and Taylor 8e
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Small Lots
•
•
•
•
Require less space and capital investment
Move processes closer together
Make quality problems easier to detect
Make processes more dependent on each other
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Inventory Hides Problems
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Less Inventory Exposes Problems
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Components of Lead Time
• Processing time
• Reduce number of items or improve efficiency
• Move time
• Reduce distances, simplify movements, standardize
routings
• Waiting time
• Better scheduling, sufficient capacity
• Setup time
• Generally the biggest bottleneck
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Quick Setups
• Internal setup
– Can be performed only
when a process is
stopped
•
SMED Principles
–
–
• External setup
– Can be performed in
advance
–
–
© 2014 John Wiley & Sons, Inc. - Russell and Taylor 8e
Separate internal setup
from external setup
Convert internal setup
to external setup
Streamline all aspects
of setup
Perform setup activities
in parallel or eliminate
them entirely
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Techniques for Reducing Setup Time
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Uniform Production Levels
• Result from smoothing production requirements
on final assembly line
• Kanban systems can handle +/- 10% demand
changes
• Reduce variability with more accurate forecasts
• 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
– makes problems visible
• Poka-yokes
– prevent defects from
occurring
• Kaizen
– a system of continuous
improvement; “change for
the good of all”
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• Jidoka
– authority to stop the
production line
• Andons
– call lights that signal quality
problems
• Under-capacity
scheduling
– leaves time for planning,
problem solving, and
maintenance
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Examples of Visual Control
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Examples of Visual Control
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Examples of Visual Control
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5 Whys
• A key part in an effective Kaizen is finding the
root cause of a problem and eliminating it
• A practice of asking “why?” repeatedly until the
underlying cause is identified (usually requiring
five questions)
• Simple, yet powerful technique for finding the
root cause of a problem
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Total Productive Maintenance (TPM)
• Breakdown maintenance
• Repairs to make failed machine operational
• Preventive maintenance
• System of periodic inspection and maintenance to
keep machines operating
• TPM combines preventive maintenance and
total quality concepts
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TPM Requirements
• Design products that can be easily produced on
existing machines
• Design machines for easier operation,
changeover, maintenance
• Train and retrain workers to operate machines
• Purchase machines that maximize productive
potential
• Design preventive maintenance plan spanning
life of machine
© 2014 John Wiley & Sons, Inc. - Russell and Taylor 8e
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5S Workplace Scan
5S Scan
Goal
Eliminate or Correct
Seiri
(sort)
 Keep only what you
need
 Unneeded equipment, tools, furniture;
unneeded items on walls, bulletins; items
blocking aisles or stacked in corners;
unneeded inventory, supplies, parts; safety
hazards
Seiton
(set in order)
 A place for
everything and
everything in its
place
 Items not in their correct places; correct places
not obvious; aisles, workstations, & equipment
locations not indicated; items not put away
immediately after use
Seisou
(shine)
 Cleaning, and
looking for ways to
keep clean and
organized
 Floors, walls, stairs, equipment, & surfaces not
clean; cleaning materials not easily accessible;
lines, labels, signs broken or unclean; other
cleaning problems
© 2014 John Wiley & Sons, Inc. - Russell and Taylor 8e
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5S Workplace Scan
5S Scan
Seiketsu
(standardize)
Shisuke
(sustain)
Goal
Eliminate or Correct
 Maintaining and
monitoring the first
three categories
 Necessary information not visible; standards
not known; checklists missing; quantities and
limits not easily recognizable; items can’t be
located within 30 seconds
 Sticking to the rules
 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
© 2014 John Wiley & Sons, Inc. - Russell and Taylor 8e
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Supplier Networks
•
•
•
•
•
•
•
Long-term supplier contracts
Synchronized production
Supplier certification
Mixed loads and frequent deliveries
Precise delivery schedules
Standardized, sequenced delivery
Locating in close proximity to the customer
© 2014 John Wiley & Sons, Inc. - Russell and Taylor 8e
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Benefits of Lean Production
•
•
•
•
•
•
Reduced inventory
Improved quality
Lower costs
Reduced space requirements
Shorter lead time
Increased productivity
© 2014 John Wiley & Sons, Inc. - Russell and Taylor 8e
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Benefits of Lean Production
•
•
•
•
•
•
Greater flexibility
Better relations with suppliers
Simplified scheduling and control activities
Increased capacity
Better use of human resources
More product variety
© 2014 John Wiley & Sons, Inc. - Russell and Taylor 8e
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Implementing Lean Systems
• Use lean production to finely tune an operating
system
• Somewhat different in USA than Japan
• Lean production is still evolving
• Lean production is not for everyone
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Drawbacks of Lean Production
•
•
•
•
•
Highly variable demand
Large variety of low-volume products
Custom engineered products
Mass production parts
Unexpected changes in demand or supply
© 2014 John Wiley & Sons, Inc. - Russell and Taylor 8e
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Lean Six Sigma
• Lean and Six Sigma are natural partners for
process improvement
• Lean
• Eliminates waste and creates flow
• More continuous improvement
• Six Sigma
• Reduces variability and enhances process
capabilities
• Requires breakthrough improvements
© 2014 John Wiley & Sons, Inc. - Russell and Taylor 8e
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Value Stream Mapping (VSM)
• A tool for analyzing process flows and
eliminating waste
• Specialized icons related to
• lean production
• material and information flows
• “aha” Kaizen bursts
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VSM Shapes
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VSM for Milling & Welding
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VSM for Emergency Room
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Lean and the Environment
• Identify environmental waste along with other
forms
• These can indicate poor process design
• Reduce costs of
• material
• energy
• regulatory compliance
• Reduce worker health and safety risks
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US EPA Recommendations
• Commit to eliminate environmental waste
• Involve staff with environmental expertise in
planning for & implementing lean events
• Find & drive out environmental waste in specific
processes by using lean tools
• Empower & enable workers to eliminate
environmental waste in their work areas
• Use environmental, health & safety icons in VSM
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Lean Services
• Basic elements of lean production apply equally
to services
• Most prevalent applications
•
•
•
•
lean retailing
lean banking
lean health care
supply chain
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Leaning the Supply Chain
• “pulling” a smooth flow of material through a
series of suppliers to support frequent
replenishment orders and changes in customer
demand
• Firms need to share information and coordinate
demand forecasts, production planning, and
inventory replenishment with suppliers and
supplier’s suppliers throughout supply chain
© 2014 John Wiley & Sons, Inc. - Russell and Taylor 8e
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Leaning the Supply Chain
• Pull a smooth flow of material through the
system
• Build a highly collaborative business
environment
• Adopt the technology to support your system
• Consider “near shoring”
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