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Transcript of chap012 v2
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McGraw-Hill/Irwin 2006 The McGraw-Hill Companies, Inc., All
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The McGraw-Hill Companies,
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McGraw-Hill/Irwin
Chapter 12
Lean Production
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Lean Production Defined
The Toyota Production System
Lean Implementation
Requirements
Lean Services
OBJECTIVES
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Lean Production
An integrated set of activitiesdesigned to achieve high-volumeproduction using minimal
inventories (raw materials, work inprocess, and finished goods) Involves the elimination of waste in
production effort Involves the timing of production
resources (i.e., parts arrive at thenext workstation just in time)
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Pull SystemHere the customer starts
the process, pulling an
inventory item from
Final Assembly
Here the customer starts
the process, pulling an
inventory item from
Final Assembly
Then sub-
assembly work is
pulled forward bythat demand
Then sub-
assembly work is
pulled forward by
that demand
The process continues
throughout the entire
production process and
supply chain
The process continuesthroughout the entire
production process and
supply chain
Customers
Sub
Sub
Fab
Fab
Fab
Fab
Vendor
Vendor
Vendor
Vendor
Final
Assembly
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Features of Lean Production
Management philosophy Pull system though the plant
WHAT IT IS
Employee participation Industrial engineering/basics Continuing improvement Total quality control Small lot sizes
WHAT IT REQUIRES
Attacks waste Exposes problems and bottlenecks Achieves streamlined production
WHAT IT DOES
Stable environment
WHAT IT ASSUMES
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The Toyota Production System
Based on two philosophies:
1. Elimination of waste
2. Respect for people
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Seven Types of Waste (Fujio Cho)
1. Waste from Overproduction
2. Waste of Waiting Time
3. Transportation Waste
4. Inventory Waste
5. Processing Waste
6. Waste of Motion
7. Waste from Product Defects
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Elements to Address Elimination
of Waste
1. Focused factory networks
2. Group technology
3. Quality at the source
4. JIT production
5. Uniform plant loading
6. Kanban production control system7. Minimized setup times
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Minimizing Waste:
Focused Factory
Networks
CoordinationSystem Integration
These are small specialized
plants that limit the range
of products produced
(sometimes only one type of
product for an entire
facility)
These are small specialized
plants that limit the range
of products produced
(sometimes only one type of
product for an entire
facility)
Some plants in
Japan have as
few as 30 and as
many as 1000
employees
Some plants in
Japan have as
few as 30 and as
many as 1000
employees
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Minimizing Waste: Group Technology (Part 1)
Saw Saw
Lathe PressPress
Grinder
LatheLathe
Saw
Press
Heat Treat
Grinder
Note how the flow lines are going back and forthNote how the flow lines are going back and forth
Using Departmental Specialization for plant layout can cause a
lot of unnecessary material movement
Using Departmental Specialization for plant layout can cause a
lot of unnecessary material movement
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Minimizing Waste:
Group Technology (Part 2)
Revising by using Group Technology Cells can reduce movement andimprove product flow
Revising by using Group Technology Cells can reduce movement andimprove product flow
Press
Lathe
Grinder
Grinder
A
2
BSaw
Heat Treat
LatheSaw Lathe
PressLathe
1
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Do it right the first time
When something goes wrong,
stop the process immediately andaddress
Workers are trained and
empowered to control their ownprocess
Minimizing Waste:
Quality at the Source
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Produce what is needed when it is
needed
Intended for repetitivemanufacturing
Low inventory, ordered only as
needed
Minimizing Waste:
JIT Production
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Minimizing Waste: Inventory
Hides Problems
Work in
process
queues
(banks)
Changeorders
Engineering design
redundancies
Vendor
delinquencies
Scrap
Design
backlogs
Machine
downtime
Decision
backlogs
Inspection
backlogs
Paperwork
backlog
Inven
to
ry
Productivity
Problems
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Work in
process
queues
(banks)
Changeorders
Engineering design
redundancies
Vendor
delinquencies
Scrap
Design
backlogs
Machine
downtime
Decision
backlogs
Inspection
backlogs
Paperwork
backlog
Inven
to
ry
Minimizing Waste: Inventory
Hides ProblemsExample: By identifyingdefective items from a
vendor early in the
production process the
downstream work is
saved
Example: By identifying
defective work by
employees upstream, the
downstream work is
saved
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Minimizing Waste:
Uniform Plant Loading (heijunka)
Not uniform Jan. Units Feb. Units Mar. Units Total
1,200 3,500 4,300 9,000
Uniform Jan. Units Feb. Units Mar. Units Total
3,000 3,000 3,000 9,000
Suppose we operate a production plant that produces a singleproduct. The schedule of production for this product could be
accomplished using either of the two plant loading schedules
below.
Suppose we operate a production plant that produces a singleproduct. The schedule of production for this product could be
accomplished using either of the two plant loading schedules
below.
How does the uniform loading help save labor costs?How does the uniform loading help save labor costs?
or
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Minimizing Waste: Kanban Production
Control Systems
Storage
Part A
Storage
Part AMachine
CenterAssembly
Line
Material Flow
Card (signal) Flow
Withdrawal
kanban
Once the Production kanban isreceived, the Machine Center
produces a unit to replace the
one taken by the Assembly Line
people in the first place
This puts thesystem back
were it was
before the item
was pulled
The process begins by the Assembly Line
people pulling Part A from Storage
Production kanban
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Determining the Number of
Kanbans Needed
Setting up a kanban system requiresdetermining the number of kanbanscards (or containers) needed
Each container represents the minimumproduction lot size
An accurate estimate of the lead time
required to produce a container is keyto determining how many kanbans arerequired
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The Number of Kanban Card Sets
C
SDL
k
)(1
containertheofSize
stockSafetytimeleadduringdemandExpected
+=
+=
k = Number of kanban card sets (a set is a card)
D = Average number of units demanded over some time
period
L = lead time to replenish an order (same units of time asdemand)
S= Safety stock expressed as a percentage of demand
during lead time
C= Container size
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Example of Kanban Card Determination:
Problem Data
A switch assembly is assembled in batches of4 units from an upstream assembly area anddelivered in a special container to adownstream control-panel assembly
operation The control-panel assembly area requires 5
switch assemblies per hour
The switch assembly area can produce acontainer of switch assemblies in 2 hours
Safety stock has been set at 10% of neededinventory
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Example of Kanban Card Determination:
Calculations
3or,75.2
4
5(2)(1.1))(1
containertheofSize
stockSafetytimeleadduringdemandExpected
==+
=
+
=
C
SDL
k
Always round up!
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Respect for People
Level payrolls Cooperative employee unions
Subcontractor networks
Bottom-round management style
Quality circles (Small GroupInvolvement Activities or SGIAs)
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Toyota Production Systems Four Rules
1. All work shall be highly specified as to content,sequence, timing, and outcome
2. Every customer-supplier connection must bedirect, and there must be an unambiguous yes-or-no way to send requests and receiveresponses
3. The pathway for every product and service mustbe simple and direct
4. Any improvement must be made in accordancewith the scientific method, under the guidance ofa teacher, at the lowest possible level in theorganization
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Accomplishing Lean Production
1. Design Flow Process
2. Total Quality Control
3. Stabilize Schedule
4. Kanban Pull
5. Work with Vendors
6. Reduce Inventory More
7. Improve Product Design
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Lean Implementation Requirements:
Design Flow Process Link operations
Balance workstation capacities
Redesign layout for flow
Emphasize preventive maintenance
Reduce lot sizes Reduce setup/changeover time
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Lean Implementation Requirements:
Total Quality Control
Worker responsibility
Measure: SQC (Statistical Quality Control)
Enforce compliance
Fail-safe methods Automatic inspection
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Lean Implementation Requirements:
Stabilize Schedule
Level schedule
Underutilize capacity
Establish freeze windows
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Lean Implementation Requirements:
Kanban-Pull
Demand pull
Backflush
Reduce lot sizes
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Lean Implementation Requirements:
Work with Vendors
Reduce lead times
Frequent deliveries
Project usage requirements
Quality expectations
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Lean Implementation Requirements:
Reduce Inventory More
Look for other areas
Stores
Transit
Carousels
Conveyors
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Lean Implementation Requirements:
Improve Product Design
Standard product configuration
Standardize and reduce number of
parts
Process design with product design
Quality expectations
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Lean Implementation Requirements:
Concurrently Solve Problems
Root cause Solve permanently
Team approach
Line and specialist responsibility
Continual education
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Lean Implementation Requirements:
Measure Performance
Emphasize improvement
Track trends
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Lean in Service Industry(How To)
1. Organize Problem-Solving Groups
2. Upgrade Housekeeping
3. Upgrade Quality
4. Clarify Process Flows
5. Revise Equipment and ProcessTechnologies
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6. Level the Facility Load
7. Eliminate Unnecessary Activities
8. Reorganize Physical Configuration
9. Introduce Demand-Pull Scheduling
10. Develop Supplier Networks
Lean in Service Industry(How To)
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Question Bowl
Lean Production seeks to achieve high
volume production using which of the
following?
a. Minimal inventory of raw materials
b. Minimal inventory of work-in-process
c. Minimal inventory of finished goods
d. All of the above
e. None of the above
Answer: d. All of the above
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Question Bowl
In the Toyota Production System,
the elimination of wasteinvolves which of the following?
a. Overproduction
b. Waiting time
c. Transportation
d. All of the above
e. None of the above
Answer: d. All of the above
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Question Bowl
In the Pull System the partner that begins
the process of pulling is which of the
following?
a. Customers
b. Vendors
c. Fabrication personnel
d. CEO
e. All of the above
Answer: a. Customer
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Question Bowl
A Lean Production program
requires which of the following?
a. Employee participation
b. Total quality control
c. Small lot sizes
d. Continuing improvement
e. All of the aboveAnswer: e. All of the above (Also included in Industrial
engineering/basics)
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Question Bowl
Inventory has been known to hide which
of the following productionproblems?
a. Scrap
b. Vendor delinquenciesc. Decision backlogs
d. All of the above
e. None of the aboveAnswer: d. All of the above
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Question BowlYou want to determine how many kanban card
sets you need for an operation. You findthat average number of units demanded is1,000 per hour, the lead time to replenish theorder for this item is 10 hours, the containersize is 10 units, and the safety stock isestimated to be 5% of the expected demand.
Which of the following is the desired numberof kanban card sets?
a. 1050
b. 1000
c. 605d. 500
e. None of the above
Answer: a. 1050 ([1000x10](1+0.05)/10=1050)
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Question Bowl
When trying to implement Lean
system a stabilized scheduleincludes which of the following?
a. Demand pull
b. Backflush
c. Fail-safe methods
d. All of the abovee. None of the above
Answer: e. None of
the above (Theseinclude: level
schedule,
underutilization
capacity, andestablish freeze
windows.)
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End of Chapter 12