Lab Tales – “Worst Case Scenario” Testing?

Cleaning sample parts in a test laboratory is one of the logical first steps in the development of a cleaning process and the subsequent specification of cleaning hardware to perform that process.  Earlier in my life, as the test lab manager for one of the largest suppliers of ultrasonic cleaning equipment in the world, I often encouraged potential customers to forward their “worst case” cleaning challenges to the laboratory thinking that if I could conquer the “worst case,” anything less would be easily handled by the cleaning process I developed for that worst case.  Since then, I have learned a few things.

First off, inviting the “worst case” is almost invariably taken as a challenge by the person preparing the samples on the other end to provide something that can not be cleaned.  I have learned that almost any potential customer, if given the opportunity and the challenge, can provide a part that absolutely CAN NOT BE CLEANED!  I have further learned that the “worst case” scenario may or may not fall within the realm of reasonability – and that, more often than not, it is outside.  Most “worst case” parts, if encountered in production, would be the result of very serious problems not at all related to cleaning and, in all likelihood, would never make it to the cleaning process anyway.  In dedication to my job, I developed many, many cleaning processes which were designed to handle “worst case” scenarios that, in the end, turned out to be far too expensive and complex to meet the customers’ needs.

It turns out that typical production samples, without any effort to make things even more difficult, already offer a greater challenge in the lab than the same parts would when cleaned on site.  Most contaminants age with time and become more difficult to remove due to the effects of drying and changes in nature both chemical and physical.  A matter of several minutes or hours let alone days or weeks, can make the difference between a contaminant that can be removed easily versus one that is difficult or impossible to remove.  Buffing compound residue is a good example of a contaminant that must be removed within minutes or hours of being deposited – if it is going to be removed at all!.

Use common sense when submitting samples to a laboratory for test cleaning.  Make sure that the samples are typical and have been processed using the same equipment and procedures that will be used in production.  “Doped up” parts will only lead to trouble in the end.  Make sure to provide details of processing to the lab along with any particular “quirks” that you may already know about the parts or the contaminants on them.  If the parts are wet, make sure they stay wet and are shipped promptly after production.  On the lab end, receipt of the samples should be anticipated so that testing can be performed as soon as possible after they arrive.

An open dialog between the potential customer and the laboratory is very important to assure that the recommended cleaning process is appropriate and cost effective.  Avoid the temptation to design for the “worst case” unless it is absolutely necessary!  And if it is absolutely necessary, be prepared for possible “sticker shock.”