Transcript Chapter 11

Chapter 11
Just-In-Time and
Lean Production
To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved.
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JIT: Definitions?
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JIT Head
Chicken JIT
Oh JIT (O´JIT)
Tough JIT
Strate JITs
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JIT Planes
Bull JIT
Le JIT
JIT Lag
When the JIT hits
the fan.
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What is JIT ?
 Producing only what is needed,
when it is needed
 A philosophy
 An integrated management system
 JIT’s mandate:
Eliminate all waste
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What is JIT?
• a corporate system designed to produce
output within the minimum lead time and
at the lowest total cost by continuously
identifying and eliminating all forms of
corporate waste and variance.
• a corporate strategy
• a philosophy
• Focus of JIT:
• variance & waste
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Seven Basic Types of
Waste
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Waste from overproduction
Waste from waiting times
Transportation waste
Process Waste
Inventory Waste
Waste of motion
Waste from product defects
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Waste in Operations
Figure 11.1
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Waste in Operations
Figure 11.1
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Waste in Operations
Figure 11.1
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Common Causes of
Waste
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• Inconsistent
Layout (distance)
performance
Long setup time
measures
Incapable processes • Ineffective
production
Poor maintenance
planning
Poor work methods • Lack of workplace
organization
Lack of training
• Poor supply
quality/reliability
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Objectives of JIT
• Produce only the products the customer wants.
• Produce products only at the rate that the
customer wants them.
• Produce with perfect quality
• Produce with minimum lead time.
• Produce products with only those features the
customer wants.
• Produce with no waste of labor, material or
equipment -- every movement must have a
purpose so that there is zero idle inventory.
• Produce with methods that allow for the
development of people
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Basic Elements of JIT
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Flexible resources
Cellular layouts
Pull production system
Kanban production control
Small-lot production
Quick setups
Uniform production levels
Quality at the source
Total productive maintenance
Supplier networks
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Flexible Resources
 Multifunctional workers
 General purpose machines
 Study operators & improve
operations
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Standard Operating Routine
for a Worker
Standard Operating Routine
Sheet 1
Order of
Operations
:10
:20
:30
:40
Worker:
Cycle Time:
Operations time
:50
1:00 1:10
1:20
Russell
2 min
1:30
1:40
1:50
2:00
Pick up
material
Unload/
load
machine 1
Unload/
load
machine 2
Unload/
load
machine 3
Inspect/
pack
Figure 11.2
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Cellular Layouts
 Group dissimilar machines in
manufacturing cell to produce
family of parts
 Work flows in one direction
through cell
 Cycle time adjusted by changing
worker paths
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Manufacturing Cell with
Worker Routes
Cell 1
Worker
1
Worker
2
Worker
3
Figure 11.3
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Worker Routes Lengthened
as Volume Decreases
Cell 1
Cell 2
Worker
1
Worker
2
Worker
3
Cell 3
Figure 11.4
Cell 4
Cell 5
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JIT Principles
• Create flow production
• one piece flow
• machines in order of processes
• small and inexpensive equipment
• U cell layout, counter clockwise
• multi-process handling workers
• easy moving/standing operations
• standard operations defined
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Balanced Production
• TAKT time
• Objective -- Build at rate that the
customer wants work
• Balance the system to maximize
efficiency at this rate
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TAKT Time
• TAKT
• the beat
• (Net Available Operating Time) /
Customer Requirements
• time periods must be consistent
• Example of calculation
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TAKT Time Example
•
Net Available Operating Time
• Time per shift
480´
• Breaks (2 @ 10´) - 20´
• Clean-up
- 20
• Lunch
- 30
• NAOT/shift
410´
• Customer Requirements
• Monthly
26,000
• No. Working Days
20
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• CR/Day
1,300
T/T
• 410´/shift*60"/min*3 shifts/1,300
• 56.769" per part or 57"
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The 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
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Kanban Production
Control System
 Kanban card indicates standard quantity
of production
 Derived from two-bin inventory system
 Kanban maintains discipline of pull
production
 Production kanban authorizes production
 Withdrawal kanban authorizes movement
of goods
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A Sample Kanban
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The Origin of Kanban
a) Two-bin inventory system
b) Kanban inventory system
Bin 1
Kanban
Bin 2
Reorder
card
Q-R
R
R
Q = order quantity
R = reorder point - demand during lead time
Figure 11.5
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Types of Kanbans
Figure 11.6
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Types of Kanbans
Figure 11.6
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Types of Kanbans
Figure 11.6
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Types of Kanbans
 Kanban Square
 Marked area designed to hold items
 Signal Kanban
 Triangular kanban used to signal
production at the previous workstation
 Material Kanban
 Used to order material in advance of a
process
 Supplier Kanbans
 Rotate between the factory and suppliers
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Determining Number of
Kanbans
average demand during lead time + safety stock
No. of Kanbans =
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 the 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)
Example 11.1
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Small-Lot Production
 Requires less space & capital
investment
 Moves processes closer together
 Makes quality problems easier to
detect
 Makes processes more dependent
on each other
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Inventory Hides Problems
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Lower Levels of Inventory
Expose 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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SMED Principles
1. Separate internal setup from
external setup
2. Convert internal setup to external
setup
3. Streamline all aspects of setup
4. Perform setup activities in
parallel or eliminate them entirely
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Common Techniques for
Reducing Setup Time
Figure 11.8
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Common Techniques for
Reducing Setup Time
Figure 11.8
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Common Techniques for
Reducing Setup Time
Figure 11.8
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Uniform Production
 Results from smoothing production
requirements
 Kanban systems can handle +/- 10%
demand changes
 Smooths demand across planning
horizon
 Mixed-model assembly steadies
component production
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Mixed-Model Sequencing
Example 11.2
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Quality at the Source
 Jidoka is authority to stop production
line
 Andon lights signal quality problems
 Undercapacity scheduling allows for
planning, problem solving &
maintenance
 Visual control makes problems visible
 Poka-yoke prevents defects
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Visual Control
Figure 11.9
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Visual Control
Figure 11.9
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Visual Control
Figure 11.9
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Kaizen
 Continuous improvement
 Requires total employment
involvement
 Essence of JIT is willingness of
workers to
Spot quality problems
Halt production when necessary
Generate ideas for improvement
Analyze problems
Perform different functions
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Total Productive
Maintenance (TPM)
 Breakdown maintenance
 Repairs to make failed machine operational
 Preventive maintenance
 System of periodic inspection & maintenance
to keep machines operating
 TPM combines preventive maintenance &
total quality concepts
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TPM Requires
Management to:
 Design products that can be easily
produced on existing machines
 Design machines for easier operation,
changeover, maintenance
 Train & retrain workers to operate machines
 Purchase machines that maximize
productive potential
 Design preventive maintenance plan
spanning life of machine
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Supplier Policies
1. Locate near to the customer
2. Use small, side loaded trucks and ship
mixed loads
3. Consider establishing small warehouses
near to the customer or consolidating
warehouses with other suppliers
4. Use standardized containers and make
deliveries according to a precise delivery
schedule
5. Become a certified supplier and accept
payment at regular intervals rather than
upon delivery
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Benefits of JIT
1. Reduced
inventory
2. Improved quality
3. Lower costs
4. Reduced space
requirements
5. Shorter lead time
6. Increased
productivity
7. Greater flexibility
8. Better relations
with suppliers
9. Simplified
scheduling and
control activities
10. Increased capacity
11. Better use of
human resources
12. More product
variety
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JIT Implementation
 Use JIT to finely tune an operating
system
 Somewhat different in
USA than Japan
 JIT is still evolving
 JIT isn’t for everyone
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JIT In Services
 Competition on speed & quality
 Multifunctional department store
workers
 Work cells at fast-food restaurants
 Just-in-time publishing for
textbooks
 Construction firms receiving
material just as needed
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