In this series on filtration I have not mentioned much about filter ratings other than to say that most filters are rated based on the minimum size of particles they will capture. It is important to know that a filter rated at 5 microns, for example, may not prevent the passage of all particles with a … Continued
Having a definition of a “clean” part and a means to quickly and effectively determine if the the criteria for cleanliness has been met is very critical to the success of any cleaning process. The problem, however, is that there are so many ways to define and detect cleanliness that the task can be a … Continued
In most manufacturing processes where metal is formed or cut, oil is used in one form or another as a lubricant. Oil and other lubricants, in order to do their job, are formulated to have very low surface tension, and, because of their low surface tension, are difficult and often impossible to control or confine. Oil spreads … Continued
I will get to the “high power” stuff in upcoming blogs but thought it would be a good idea to introduce a few more tests that are simple and require little or no specialized paraphernalia. Simple is good in my opinion especially when you are troubleshooting in a remote location or when you are working … Continued
So far in this series we have concentrated primarily on the detection of oil and other hydrophobic films on surfaces. However, not all contaminating films are oil and all are not hydrophobic. What about contaminants that are not hydrophobic and may even by hydrophilic (residual soaps and surfactants, for example) as well as things like oxides? These are just … Continued
The evaluation of cleanliness is often based on a quantification of the particles left on a surface following the conventional or production cleaning process. The first step in evaluating a part for cleanliness with regard to particles is to harvest those particles that remain after cleaning. Once harvested, the particles can be counted, weighed, microscopically … Continued
Those of us who have played the particle counting game know that there are some tough calls when it comes to harvesting particles as part of the cleanliness testing procedure. In some cases, adhering strictly to the specification would result in the rejection of every part tested. Although I do not believe that rules are … Continued
Before we get into quantifying the particles we have harvested in the last few blogs, I would like to take a minute or two to talk about the specifications that define and govern the evaluation process. In upcoming blogs we will talk about the quantification of particles in general terms. In real life, there is … Continued
There are a number of metal finishing process which should be avoided in the manufacture of items subject to demanding specifications with regard to the presence of particles. These common processes, although employed with the best intent, result in the generation or unavoidable entrapment of particles which may be released under use conditions with potentially … Continued
The test laboratory is a special kind of place. The work conducted in the laboratory is experimental which usually indicates that we are trying things that have not been tried before to see what happens or doesn’t happen. Fortunately, at least in the cleaning laboratory, it is not likely that we will initiate an uncontrolled … Continued