Transcript Just-In-Time Manufacturing

Session 19
Just-In-Time Manufacturing
• JIT Impact on the MPC System
• JIT Continuous Improvement
– JIT Building Blocks
– Elements of JIT
• Kanban Systems
– Single Card Kanban
– Kanban Calculations
• JIT Impact on the MPS
– Mixed Model Final Assembly
– JIT Assembly/Component Scheduling
1
JIT Impact on the MPC System
• Eliminating discrete batches in floor of
production rates
• Level, mixed model MPS
• Paperless, visual shop floor control
• Eliminating transactions/Backflushing
• Streamlined vendor scheduling
2
Manufacturing Planning and
Control System and JIT
3
Building Blocks for Just-in-Time
4
JIT Benefit Summary
Improvement
Aggregate
percentage
(3-5 years)
Manufacturing cycle time reduction 80-90%
Inventory reductions:
Raw materials
35-70
Work-in-process
70-90
Finished goods
60-90
Labor cost reductions:
Direct
10-50
Indirect
20-60
Space requirements reduction
40-80
Quality cost reduction
25-60
Material cost reduction
5-25
Annual percentage
30-40%
10-30
30-50
25-60
3-20
3-20
25-50
10-30
2-10
5
JIT Objectives
Ultimate objectives:
• Zero Inventory.
• Zero lead time.
• Zero failures.
• Flow process.
• Flexible manufacture.
• Eliminate waste.
6
JIT Building Blocks
• Product design:
Few bill of material levels.
Manufacturability in production cells.
Achievable quality.
Appropriate quality.
Standard parts.
Modular design.
7
JIT Building Blocks
• Process design:
Setup/lot size reduction.
Quality improvement.
Manufacturing cells.
Limited work-in-process.
Production bandwidth.
No stockrooms.
Service enhancements.
8
JIT Building Blocks
• Human/organizational elements:
Whole person.
Cross training/job rotation.
Flexible labor.
Continual improvement.
Limited direct/indirect distinction.
Cost accounting/performance measurement.
Information system changes.
Leadership/project management.
9
JIT Building Blocks
• Manufacturing planning and control:
Pull systems.
Rapid flow times.
Small container sizes.
Paperless systems.
Visual systems.
Level loading.
MRP interface.
Close purchasing/vendor relationships.
JIT software.
Reduced production reporting/inventory transaction
processing
Hidden factory cost reductions.
10
Single Kanban System
11
Kanban Calculation
1. Calculate the number of kanbans
required for the following two components
produced in a factory that works five days
per week:
A
B
Usage
240/week
120/day
Lead time
1 week
2 weeks
Container size 20 units
30 units
Safety stock 25 percent
0
12
Kanbans Calculations
Usage (per week)
A
240
B
600
Lead time
Container size
Safety %
Kanbans
1
20
25
15
2
30
0
40
Number of Kanbans = Usage x Lead time x (1 + safety stock) / container size
Note that B's Usage must be converted to weeks
A: 240 u/week x 1 week x (1 + .25)
20
= 15
B: 120 u/day x 10 days x (1 + 0)
30
= 40
13
Master Production Schedule Data
Model
_______________________________________________________________
151A
151B
151C
151D
Option configurations:
Handle
Basic
Basic
Executive Executive
Pan
Sheet
Clad
Sheet Clad
Annual forecast (units)
200,000 2,500
25,000 100,000
Possible mixed model
master production
schedules:
Daily batch MPS
800
Hourly batch MPS
100
Minimum batch MPS 80
10
1.25
1
100
12.5
10
400
50
40
* data are based on a 250-day year and an eight-hour work day.
14
Mixed Model Final Assembly
5. The Yakima Lash Company produced four models. The
forecasts of annual demand for each of the four are as
follows:
Model
I
II
III
IV
Forecast of annual demand
500 1,500 3,500 4,500
a. Use a 250-day year and an eight-hour day to determine
the mixed-model-level master schedule for a daily batch
and hourly batch with minimum batch sizes.
b. What would the schedule of production look like for an
eight-hour day using mixed-model minimum batch size
production?
15
Problem 5. Yakima Lash Company
a. Product line
Forecast for year
Daily batch
Hourly batch
Mixed model
I
500
2
.25
1
II
1,500
6
.75
3
III
3,500
14
1.75
7
IV
4,500
18
2.25
9
b. Schedule for the day-order of the products' production
and number of each produced.
8-12: IV,IV,IV,IV,IV,IV,IV,IV,IV,III,III,III,III,III,III,III,II,II,II,I
12-4: IV,IV,IV,IV,IV,IV,IV,IV,IV,III,III,III,III,III,III,III,II,II,II,I
16
Assembly/Component Scheduling
Hofmann Enterprises produces three products using a
mixed-model assembly line. This line is operated eight
hours a day for 250 days per year, and produces 14
units per hour of all products. The forecasts of annual
demand for each of the three products are as follows:
Product
Annual
(code names)
forecast
John
16,000 units
Goldie
8,000 units
Ziggy
4,000 units
17
Hoffman Enterprises Example
a.
Determine the mixed-model master production schedule for a
daily batch with minimum batch size for all three products.
Calculation made assuming a 250 day year
Annual
Daily
Mixed Model
Product
Forecast
Production
Minimum Batch Size
John
16000
64
4
Goldie
8000
32
2
Ziggy
4000
16
1
18
Hoffman Enterprises Example
b.
Prepare a daily schedule indicating the number of Johns, Goldies,
and Ziggys to be produced each day.
Hours of the Day
1
2
3
4
5
6
7
8
John John
John
John
John
John
John
John
John John
John
John
John
John
John
John
John John
John
John
John
John
John
John
John John
John
John
John
John
John
John
Goldie Goldie
Goldie Goldie Goldie Goldie Goldie Goldie
Goldie Goldie
Goldie Goldie Goldie Goldie Goldie Goldie
ZiggyZiggy
Ziggy Ziggy Ziggy Ziggy Ziggy Ziggy
John John
John
John
John
John
John
John
John John
John
John
John
John
John
John
John John
John
John
John
John
John
John
John John
John
John
John
John
John
John
Goldie Goldie
Goldie Goldie Goldie Goldie Goldie Goldie
Goldie Goldie
Goldie Goldie Goldie Goldie Goldie Goldie
ZiggyZiggy
Ziggy Ziggy Ziggy Ziggy Ziggy Ziggy
19
Hoffman Enterprises Example
c.
Product John requires 2 units of component X and one unit of
component Y to make a finished unit of John. Component X is
produced on a JIT pull system basis by a separate manufacturing
department. Determine the number of kanbans required for
component X if the lead time is 2 days, the safety factor is 10%,
and the container size is 20 units.
# Kanbans = [ 2 x 64 x 2 x (1 + .10) ] / 20= 15
Usage
128/day
Lead Time
2 days
Safety Percent Container Kanbans
10%
20 units
15
20