Transcript Document

Lean Manufacturing
Continuous Flow
Dr. Richard A. Wysk
[email protected]
http://www.engr.psu.edu/cim
June 12, 2002
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Readings
• “Even in a topsy-turvy world, just-in-time supply works,”
by James P. Womack and Daniel T. Jones. Automotive
News, Oct. 29, 2001.
• “Lean Time, Lean Measures,” by Michael San Filippo,
January/February 2002 Interview.
• “Building the Lean Machine,” Advanced Manufacturing,
January 2000.
• Chapter 18 of Computer Aided Manufacturing, Wang,
H.P., Chang, T.C. and Wysk, R. A., 3rd Edition (2004
expected)
http://www.engr.psu.edu/cim/active/chapter18.pdf
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Exercise
Readiness Assessment Test
A.K.A. RAT
AS A INDIVIDUAL, look at the detailed
requirements for a production process. We will
look at the Case Study and Key holder.
• What is the operation time for the Key holder at
each workstation in a production system?
• How is this time related to the time required to
produce a key holder?
• What is the difference between production time
and setup time?
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Open Book / Open Notes
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Exercise
Readiness Assessment Test
A.K.A. RAT
AS A TEAM, take 3 minutes to provide a written
to answer the following questions:
• Did all operations require the same time?
• What is best operation to focus attention of for the
key holder?
• Why?
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Closed Book / Closed Notes
Objectives
• To apply the principles of flow to a
complex manufacturing system
• To design the layout of process, product
and cellular manufacturing systems
• To implement a pull system in a
manufacturing environment
• To analyze efficiencies of reduced batch
sizes
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Exercise (3 – 5 minutes)
• Individually answer the following
questions
• What percent of time does a part spend
having “value added” to it while the part
is on the shop floor?
• What are the top 5 causes of “non-value
added” times?
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Quick Change Over
QCO is used to:
• Reduce time needed to change over from
one set-up to another.
• Improve first time capability.
• Improve repeatability of change over
operations
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Total Productive Maintenance
• TPM is a structured approach to
maintaining equipment and insuring stable
manufacturing processes.
• Everybody gets involved.
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What to Expect in the Future
•
•
•
•
•
•
•
•
•
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Training
Communication
Elimination of Waste (NVA)
Continuous Improvement
Visual Factory
More efficient layouts
Roles & Responsibilities
More involvement / ownership
Long term GROWTH!!
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Types of Manufacturing Layout
• Process Layout
• Product Layout
• Cellular Layout
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FUNCTIONAL LAYOUTS ARE INEFFICIENT
Drilling
Milling
Lathe
L
L
M
M
L
L
M
M
D
D
D
D
Grinding
L
L
M
M
Assembly
L
L
A
A
Receiving and
Shipping
A
A
G
G
G
G
G
G
PROCESS-TYPE LAYOUT
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Process Layout Characteristics
• Advantages
– Deep knowledge of the process
– Common tooling and fixtures
– Most Flexible -- can produce many different part types
• Disadvantages
– Spaghetti flow -- everything gets all tangled up (can not
“pull” materials with this layout)
– Lots of in-process materials
– Hard to control inter-department activities
– Can be difficult to automate
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PRODUCT LAYOUT
Part #1
L
L
M
D
G
A
Receiving
L
M
G
A
G
Part #2
Part #3
L
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M
D
Shipping
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Product Layout Characteristics
• Advantages
– Easy to control -- input control
– Minimum material handling -- frequently linked to the
next process
– Minimal in-process materials
– Can be more easily automated
• Disadvantages
– Inflexible -- can only produce one or two parts
– Large setup
– Duplicate tooling is required for all cells
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CELLULAR LAYOUT
Cell #2
Cell #1
D
D
M
I
D
I
L
Cell #3
L
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L
D
M
M
I
M
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Cellular Layout Characteristics
• Advantages
– Control is simplified
– Common tooling and fixtures
– Flexible -- can produce many different part types - a
part family??
• Disadvantages
– Setup ??
– Need to know about many different processes
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Evidence of Progress toward Lean
•
•
•
•
•
•
•
•
•
•
Smaller lot sizes
Increased capacity / throughput
Higher inventory turns
More available floor space
Improved workplace organization
Improved quality : reduced scrap / re-work
Reduced inventories : raw, WIP, FG
Reduced lead times
Greater gross margin
Improved participation & morale
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Lean Mfg Implementation
Timeline
•
•
•
•
•
•
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LMA – 6 to 12 weeks
(Prototype line/experimentation?)
Management commitment – 4 to 6 months
Prep for implementation – 6 to 8 months
Model line development – 6 months to 1 year
Program expansion – 1 to 3 yrs
Beginnings of the ‘Lean Enterprise’ – 3 to 5
yrs
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Price Increase
3
Price to
Sell
3
Some Profit
Cost to
Produce
2
1
Bigger Profit
2
1
Cost + Profit = Price
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Cost Reduction
Price to
Sell
1
Some Profit
Cost to
Produce
1
3
2
Bigger Profit
3
2
Price - Cost = Profit
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Counting
Storing
Sorting
Moving
Acknowledgments
Invoices
Expediting
What value is
Added by:
Rework
Inspecting
Loading / Unloading
Scrap
Returns to Suppliers
Repackaging
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Receiving Report
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Toyota Production System
Best Quality - Lowest Cost - Shortest Lead Time
Through shortening the Production Flow by Eliminating Waste
Just in Time
Jidoka
“The right part
at the right time
in the right amount”
“Built in Quality”
• Continuous Flow
• Pull System
• Level Production
(Heijunka)
Standardized Work
Total Productive Maintenance
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Flexible, Capable,
Highly Motivated
People
Operational Stability
• Manual / Automatic
Line Stop
• Labor-Machine
Efficiency
• Error Proofing
• Visual Control
Robust Products & Processes
Supplier Involvement
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Just in Time Manufacturing
Produce according to customer demands:
• What is needed
• When it is needed
• In the quantity it is needed
Utilize
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- Continuous flow processing
- Pull system
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Push System
Lot arrival triggers production
Material
Information
MRP Schedule triggers Production
Example: MRP
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Pull Systems
Material
Information
Withdrawal of
material triggers
production
Production schedule is issued only to final assembly line.
Production schedule for each of the preceding process is
determined by transfer of parts
Parts are pulled through the system from the end of the line
to the start
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• Parts are produced only when needed (or
just in time)
• less delay or lead time, lower inventory
• KANBAN - is the manual system to
implement the pull system
• JIT - refers to the whole system, the
material flow and management philosophy
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JIT Systems
• Combines both the production control
component and a management philosophy
• 4 basic tenets for the success of JIT
–
–
–
–
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Elimination of waste
Employee Involvement
Supplier Participation
Total Quality Management
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Kanban
• Manual information system to control
production. Material transportation, and
inventory
• Literally means “visible record” or card
• In the the broad sense it is a communication
signal from a downstream process
(customer) to a upstream process (producer)
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Kinds of Kanban
• Two most common kanbans
– production kanbans (P- Kanban)
• authorizes a process to produce a fixed amount of
product
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Kanban continued
• Transportation kanban (T- Kanban)
– authorizes transporting a fixed amount of
product downstream
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JIT Element - Continuous Flow Processing
Batch Processing
10 minutes
10 minutes
10 minutes
Total Batch A processing time : 30 minutes
Continuous Flow Processing
Total Batch A processing time : 12 minutes
Only 3 minutes for 1st part
•Product requires three processes that take one minute each
•Processing first batch in batches of 10 requires 30 minutes
•Processing first “batch” one-at-a-time requires only 12 minutes
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JIT Element - Pull System
• Following processes withdraw what they need when they need it.
• Preceding processes replenish what is taken away.
Production Kanban
Withdrawal Kanban
Upstream
Processes
New
Product
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
Store
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Pull
Downstream
Processes
Needed
Product
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Production Scheduling
Assumptions
• Production Schedules will always change
• Production will never go according to
schedule.
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Takt time
Takt time - takt, is a German term for rhythm. Takt time is the
allowable time to produce one product at the rate customers are
demanding it. This is NOT the same as cycle time, which is the normal
time to complete an operation on a product (which should be less than or
equal to takt time).
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Takt Time
Takt Time
Time (Available seconds per working day)
=
Volume (Daily production requirement)
Sets pace of production to
match pace of sales.
Cycle Time
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=
Actual time required for a worker to
complete one cycle of his process
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Balanced Cycle Times
Takt Time (1 min.)
1 min.
Cycle Time
Operators
A
B
C
D
E
Takt Time (1 min.)
1 min.
Operators
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A
B
C
D
E
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Very Frequent Change-over
Left Hand
Left Hand
change over
change over
Right Hand
change over
Right Hand
Left Hand
change over
change over
Right Hand
change over
Left Hand
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8 hours
Left Hand
change over
change over
Right Hand
change over
Right Hand
Left Hand
change over
change over
Right Hand
change over
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Building in Quality
JIDOKA
Machines
intelligence to be self-operating and
self-stopping
People
served by machines, not vice versa
Quality
built-in, not inspected-in
Efficiency human work separated from machine
work, people freed to do value-added
work
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Quality Processes Yield Quality Results
Inconsistent
Process
Inconsistent
Results
Traditional = People doing whatever they can to get results
Consistent
Process
Desired
Results
Lean = People using standard process to get results
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Impact on You!!
First Time Quality
•
Standardized Work
People
•
Error Proofing
•
•
Root Cause Analysis
– Problem Solving
•
Change Request Forms
•
Predictable Processes
– Machine Reliability
– Total Productive
Maintenance
– Improved up-time
•
•
•
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Reduced scrap & repairs
•
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Skilled, multi-function
workers
– Training
– Employee development
Small Group Activity
– Quality
– Safety
– Productivity
– Cost
Structured feedback meetings
Empowerment
– Involvement
– Accountability
– Responsibility
– Authority
Safety & Ergonomics
Just in Time
•
Kanban production
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Min / Max levels
•
Smaller Lots
•
Quick Change Over
•
Less inventory
•
Less reliance on schedules
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Exercise – (3 – 5 minutes)
• As a group, discuss a situation that you
are familiar with where continuous
flow would improve a systems
performance.
• Is this flow limited to manufacturing?
• Prepare to respond to the entire class?
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Questions?
There are no stupid questions!
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