|
Lean
Resources
Lean
Manufacturing Video
"The
Human Side of Lean Manufacturing"
Click
For Preview
Purchase
Video
Download
This series in
printer-friendly PDF format.
|
|
 The principle of Mixed Model
Production is simple enough.
Designing the process and system is often more difficult. In this
page we explore common
roadblocks and describe some
techniques to eliminate them.
When
people are enmeshed in an existing system they have difficulty
envisioning how mixed model, smoothly flowing production is
possible. It helps to ask two key questions:
1. What must be true for this to
work?
2. How could we make it true?
Thoroughness
and tenacity can often make various conditions true and achieve (or come close to) the ideal model
of a smoothly flowing stream. |
Mixed Model Pages
0. Mixed Model Introduction
1. Assembly Line With Changeover
2. Mixed Model Lines
3. Smoothing With Assembly Cells
4. Integrated Workcells
5. Problems To Address
Download
This series in
printer-friendly PDF format.
|
Mixed Model Assembly Lines
|
Problem |
Description |
Solutions |
|
Work Balance |
When different models have different work content,
operations must be flexible
enough to deal with the product mix. |
-
A constantly moving line only lends itself to
mixed model production when work content is nearly identical for
each station. See Balancing Workcells.
-
Small Queues between stations to
accommodate short-term variation.
-
Adjacent workers share tasks and help each other.
-
Fewer stations and longer task
times.
|
|
Part Availability |
For a mixed model assembly line to function,
every part for every product must be immediately available.
|
|
|
Tool Availability |
Tools and special fixtures must be
readily available. (This is seldom a problem when the
product is small. It may be a problem with large products such as
refrigerators or vehicles.) |
|
|
Fabrication Setup
Reduction |
Dedicated fabrication
equipment is not always available. Long,
expensive and/or inconsistent changeovers force
large
batches and high inventory between fabrication and the mixed model
line. |
- Setup Reduction In Fabrication
with small lots.
- Redesign fabrication processes
with more dedicated equipment, even (if necessary) at the cost of decreased
labor efficiency.
- Investigate alternate processes.
|
Dedicated Assemby Cells
|
Problem |
Description |
Solutions |
|
Demand Variability |
Variation
in demand for each dedicated cell may be larger than the variation
for a single line. (Peaks and valleys of demand often cancel
when combined.) |
- Design assembly cells for
multiple levels of staffing.
- Move people between cells to
balance output & demand.
- Provide excess equipment
capacity to handle peak demands.
|
|
Cell Design |
Workcells appear simple and this is especially true for assembly
cells. In reality they are complex and sometimes sensitive
socio-bio-technical systems. |
|
Integrated Cells
|
Problem |
Description |
Solutions |
|
Process
Incompatibility |
This
usually involves processes that must be isolated for environmental
reasons (Dust, Dirt, Chemicals or Noise). |
- Address the environmental
problem with dust control, noise control, etc.
- Investigate alternate processes.
|
|
Process Scale |
Large-scale fabrication processes have too much capacity for a
single assembly cell. |
- Investigate alternate equipment
and methods. (e.g. small, manual paint booth replacing a large
paint line)
|
|
Special Skills |
Certain
tasks require extensive skills, experience and/or training but do
not require a full-time operator for each cell. |
- Tools, fixtures or gages that
require less skill
- Train or cross train
- Train cell workers in basics
with consultant employee for difficult problems. The daily tasks often do
not require high skills or knowledge.
|
|
