Chapter
6 Lean Systems
How does a lean system affect a firm’s internal linkages between its core and supporting
processes and its external linkages with its customers and suppliers?
1. Marketing:
2. Human resources:
3. Engineering:
4. Operations:
5. Accounting:
1. Continuous Improvement Using a Lean Systems Approach
1. Define just-in-time
2. Define Kaizen
3. Eight types of waste
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
4. Lean systems provide what mechanism and philosophy?
5. Describe the philosophy
a. In services
b. In manufacturing
c. What do the rocks represent?
2. Strategic Characteristics of Lean Systems
1. Supply Chain Considerations in Lean Systems
a. Close supplier ties
b. Small lot sizes
• Advantages
• Disadvantages
2. Process Considerations in Lean Systems
a. Pull method of work flow
• Describe a push method
• Describe a pull method
• How can the choice between the push and pull methods be determined?
b. Quality at the source
• How obtained and defined?
• Poka-yoke
• Jidoka or andon
c. Uniform workstation loads
• takt time
• heijunka
• mixed-model assembly
• lot size of one
d. Standardized components and work methods
e. Flexible workforce
f. Automation
g. Five S practices
• Sort
• Straighten
• Shine
• Standardize
• Sustain
h. Total preventive maintenance
3. Toyota Production System
a. House of Toyota
• The roof
• The twin pillars
• The base
3. Designing Lean System Layouts
1. One worker, multiple machines (OWMM)
2. Group Technology
4. The Kanban System
Define Kanban
1. General operating rules
a.
b.
c.
d.
e.
f.
2. Determining the number of containers
a. Management must make two determinations
• The number of units to be held by each container
• The number of containers flowing back and forth between the supply station and the
user station
b. Formula for the number of containers
containerper units ofNumber
stocksafety timelead during demand Average +
=k
( )
( )
c
d
++
=1
c. Application 6.1: Determining the Number of Containers
Item B52R has an average daily demand of 1000 units. The average waiting time per
container of parts (which holds 100 units) is 0.5 day. The processing time per container is
0.1 day. If the policy variable is set at 10 percent, how many containers are required?
( )
( )
=
++
=c
d
k
1
where
number of containers for a part
=d
expected daily demand for the part, in units
=
average waiting time during the production process plus materials handling time per
container, in fractions of a day
=
average processing time per container, in fractions of a day
=c
quantity in a standard container of the part
=
a policy variable that adds safety stock to cover for unexpected circumstances
4. Other Kanban Signals
a. Container System
b. Containerless System
5. Value Stream Mapping
Define value stream mapping (VSM)
Why is VSM helpful?
1. Current State Map
a. Value Stream Mapping Steps
•
•
•
•
2. Application 6.1: Determining the Value Stream Map, Takt Time, and Total Capacity
The manager at Gilman’s Inc. collected the value stream mapping data from the plant’s
most problematic manufacturing cell that fabricates parts for vending machines. This
data is shown below. Using this data, calculate the current state performance of the cell
and answer the following questions.
Overall Process
Attributes
Average demand: 200/day
Batch size: 20
Number of shifts per day: 2
Availability:8 hours per shift with a 45-minute break
Processing Step 1
Cut
Cycle time = 160 seconds
Setup time = 3 minutes
Up time = 100%
Operators = 1
WIP = 600 units (Before Cut)
Processing Step 2
Grind
Cycle time = 120 seconds
Setup time = 1 minute
Up time = 99%
Operators = 1
WIP = 800 units (Before Grind)
Processing Step 3
Bend
Cycle time = 240 seconds
Setup time = none
Up time = 100%
Operators = 1
WIP = 400 units (Before Bend)
WIP = 600 units (After Bend)
Customer Shipments
One shipment of 1000 units each week
Information Flow
All communications with the customer are electronic
There is a weekly order release to Cutting
All material is pushed
a. What is the cell’s current inventory level?
b. What is the takt time for this manufacturing cell?
c. What is the production lead time at each process in the manufacturing cell?
d. What is the total processing time of this manufacturing cell?
e. What is the capacity of this manufacturing cell?
3. Future State Map
6. Operational Benefits and Implementation Issues
1. Organizational considerations
a. Human costs of lean systems
b. Cooperation and trust
c. Reward systems and labor classifications
2. Process considerations
3. Inventory and scheduling
a. Scheduling stability
b. Setups
c. Purchasing and logistics