Clean can be Lean, Part I
By Ed Kanegsberg
[Note: An expanded version of this article, with examples, will be presented
at CleanTech2005, during National Manufacturing Week, in March. Please
see link under “Upcoming Events”]
We are constantly preached the doctrine of Lean Manufacturing. We are told
that if you’re not lean, you’re not manufacturing competitively;
and your business will fail. Many actually have Lean Manufacturing techniques
in place in their production facilities.
A key premise for a process step to be lean is that it be value-added. However,
some managers think that any cleaning step is a necessary annoyance, not
a value added step. So how can clean be lean?
There are instances where, for a fiscally significant percentage of the parts
being processed:
coating won’t stick
adhesives won’t bond
surface quality degrades after heat treatment
As an engineer or process chemist, you may know that improved cleaning avoids lost product and saves money. Your boss may balk at a new process. Put yourself in the position of the bean-counters – do the math. A little time spent calculating value-added can justify the new process.
Failures, whether during or after manufacturing, are all too often attributable
to inadequately removed contamination. So cleaning, or any other euphemism
for a process that removes contamination that could potentially cause product
failure, is a value-added step.
The following three examples, all related to product failure, illustrate ways
in which inadequate or inappropriate cleaning gives rise to additional
costly processes and costly consequences.
a. Rework
Rework stemming from a process-related failure is one of the largest cost drivers
in manufacturing. A part that doesn’t yield must either be reworked or
scrapped. There are two aspects to the costs when you have to rework. One aspect
is the time, labor, and materials involved in repeating a process that has
already been performed. A second aspect is that backtracking may involve additional
processes to undo what has been done before. For example, suppose a coating
adheres inadequately. Rework involves first removing the coating, appropriately
disposing of the coating, again preparing the surface, and reapplying the coating.
b. Scrap
With scrap, the product cannot be repaired or reworked. Therefore, we lose
the time and other costs it took to produce the defective product. The scrap
has to be disposed of; and the complete build process must be repeated.
c. Latent failure
Product failures that are detected by appropriate in-line inspection techniques
are costly. Product failures that escape detection or fail after delivery to
the customer are usually more costly. In this case, not only do you have the
costs of replacing the part, but, more importantly, of repairing your reputation
as a supplier of quality parts. Product failure, especially in the bio-medical
arena, can lead to nasty and extremely costly litigation.
In the next issue of “Clean Source,” we will address how to apply lean principles to a cleaning process.
