Page 37 - How To Implement Lean Manufacturing

18 Cha pte r T w o

Frequently, there will be specific tools at the line to signal if cycle time is being met
or not. Common among these tools are the heijunka board. Where heijunka boards are
not used, it is common to see counters and/or clocks to assist the workers and advise
them if the process has slowed for some reason. These tools are not supervisory in
nature, they are supplied for diagnostic purposes so process deterioration can be found
and corrected. In addition, the concept of transparency of Lean systems has the element
known as Standard Work (SW). SW is a set of tools, one of which is a flow chart with
cycle times for each process step, so a supervisor, engineer, or manager can evaluate
how well the process is performing and assist in process improvement.

How Line Availability Is Managed
In MassProd, line and machine availability, like cycle time, is seldom measured, thus it
is typically not known or managed. If production should fall behind schedule, the typi-
cal response is usually overtime and expediting. In the Lean facility, availability is
known, understood, and managed. The key issues in availability problems usually center
on two issues. The first issue is materials, either defective material not allowing the
process to perform, or stock outs. The answer to both can be kanban or other pull system
tools. The second problem that adversely affects availability is usually equipment
downtime. Tools like andons exist to signal problems, but the key tool used in the
improvement of availability is Total Productive Maintenance (TPM).

Summary of Technical Issues
The following essentially summarizes the majority of the technical issues in the TPS:
• Production cells flowing using pull production systems
• Balanced, so synchronized flow is achieved
• Producing at takt rate
• Using kanban to reduce inventory
• Rate and product mix leveled to minimize inventory
• Using cycle/buffer/safety stocks to handle internal and external rate fluctua-
tions (while keeping cell production stable)
What we find by reviewing this list of tools and techniques in the Lean facility is a
clear lack of uniqueness. The use of cells and line balancing to minimize labor costs are
engineering techniques that have been around for a long time and clearly preceded the
TPS. The use of strict inventory controls, operating at takt, SMED and poka-yoke tech-
niques are not really new, but are applied with a rigor and a vigor in Lean not seen in
MassProd. So they are different only in the way they are applied, but they certainly are
not revolutionary. So technically there is a difference in the application, but compared
to the last three aspects of the five-part definition of the TPS definition, the technical
and operational differences are relatively minor.

The Integrity of the TPS
The third major difference is the integrity of the system. Most people think honesty is a
synonym for integrity. It is not. Integrity has come to mean honesty because so many