Lean thinking and methodology have resulted in many organizations instituting powerful initiatives and gaining major improvements, but most still associate Lean principles with low-mix high-volume (LMHV) manufacturers. There are, however, a gamut of high-mix low-volume (HMLV) manufacturers that wonder if the power of Lean is really applicable to them given their very different factors regarding volume, variety, and scheduling.
I recently spoke with Shahrukh Irani – who
actually just published a book entitled Job Shop Lean: An Industrial Engineering Approach to Implementing Lean in High-Mix Low-Volume Production Systems –
and asked him the very specific question: “How is Lean applicable in High-Mix Low-Volume (HMLV) manufacturing?” Here is his detailed answer:
Of all high-mix low-volume (HMLV)
manufacturers, a job shop has the most complex production system. The classification of different production
systems that is shown in Figure 1 provides the simplest evidence that forcing a
job shop to adopt a production system and tools that were designed to improve a
repetitive assembly line’s performance is like fitting a square peg into a
round hole.
Figure 1: Comparison of an Assembly Plant and a
Custom Fabrication Job Shop
Currently, nearly every job shop has failed to realize the full gains from Lean because they have stopped at implementing only the Lean tools listed in the left-hand column of Table 1. In contrast, the Lean tools in the right-hand column of Table 1 are ineffective, often inapplicable, in any job shop. So how does any Lean job shop reap additional benefits from Lean? By implementing a new “Job Shop Lean Toolbox” in which the Lean tools in the right-hand column of Table 1 have been replaced with other tools that were developed for job shops!
Table 1: A
New “Job Shop Lean Toolbox” for High-Mix Low-Volume Manufacturers
|
Lean tools that will work in job shops
also |
Lean Tools that will not work in job
shops |
|
Strategic Planning |
Pencil-and-Paper Problem Solving |
|
Top-Down Leadership |
Value Stream Mapping |
|
Gemba Walks by Managers |
Assembly Line Balancing |
|
Employee Engagement |
One-Piece Flow Cells |
|
Workplace Design with 6S |
Product-specific Kanbans |
|
TPM (Total Productive Maintenance) |
FIFO Sequencing of Orders |
|
Setup Reduction (SMED) |
Pacemaker Scheduling |
|
Error-Proofing (Poka-Yoke) |
Inventory Supermarkets |
|
Quality At Source |
Work Order Release based on Pitch |
|
Visual Workplace |
Production based on Level Loading |
|
Product and Process Standardization |
Mixed Model Production with Takt Time |
|
Right-sized Flexible Machines |
Right-sized Inflexible Machines |
|
Standard Work |
Pull-based Production Scheduling |
|
Continuous Problem-Solving |
Manual Scheduling with Whiteboards |
If
the Tool Works for High-Mix Low-Volume, Then Job Shop Lean Uses It!
In Table 1, the tools in the
left-hand column will also work in HMLV production systems. “Top-down
Leadership” and “Employee Involvement” are essential. “Standard
Work Instructions” and “Setup Reduction”
are needed to minimize variation in setup times on any machine (or
manufacturing cell) due to different parts having varying setup sequences,
tooling packages, material sizes, tolerances, etc. “Quality at Source” empowers employees to
reduce costs, take pride in their workmanship and have ownership for their
work. “Right-sized Machines” appears in
both columns of Table 1 because simple machines are easy to learn to use,
setup, operate and maintain.
If
the Tool Does Not Work for High-Mix Low-Volume, Then Job Shop Lean Replaces It!
In Table 1, the tools in the
right-hand column will almost never work in HMLV production systems because
those tools are simply not applicable to MTO (Make-To-Order) HMLV production
systems that do not operate like assembly lines. It is these tools that have been replaced by
a more effective set of tools, often enabled by software, to successfully implement
Job Shop Lean.
What do you think of Shahrukh's observations? What are the experiences of those who work in a HMLV environment and have been part of a Lean initiative?
