This is one of those columns you have to read (and write) every couple of years or so. It’s like taking a physical—necessary to the long-term health of the business, but otherwise a boring waste of time. It’s not going to be quite as tedious as answering “Why am I here?” or “Why is there air?” but it’s in that realm.
The purpose of this short column is to supplement your thinking about what it is you’re trying to do in your controlled environment with why you’re trying to do it. One should think this way when contemplating changes in design, purchase, or cleaning systems.
WHY IS THERE TIME?
How does critical cleaning differ from precision cleaning, and how does precision cleaning differ from metal cleaning? Since this is not a scientific definition, others will have different opinions. Here are mine.
WHAT’S IN SPACE?
My simplest definition of critical cleaning is less inclusive than that of Supreme Court Justice Potter Stewart who said that he couldn’t define pornography but he could recognize it when he saw it. Nearly everyone thinks the cleaning work they do is critical—to them.
My best definition, based on the details associated with cleaning work, of metal, precision, and critical cleaning is shown in Table 1.
CAN ONE HAVE TOO MUCH VACUUM?
Yet, this definition isn’t perfect. I have found metal cleaning at a site making instruments via micro machining technology and critical cleaning at a site making kitchen faucets.
We teach that there are common principles in all three types of cleaning work. For example, metal, precision, and critical cleaning are based on some combination of three factors: heat or temperature, mechanical force, and detergency or solvency. But the details of implementation are totally dependent upon the application.
Further, in one sense the distinctions among metal, precision, and critical cleaning are artificial— one uses what toys, techniques, tests, etc. one needs to meet the requirements of the operation. So, often the real question is: What are the requirements of the operation?
WHAT IF TWO BLACK HOLES COLLIDE?
Finally, more than one type of cleaning work with the same piece can be done in different or sequential treatment steps. That is, a precision cleaning operation may precede one of critical cleaning. However, the reverse would be a mistake!