The first step to an understanding of ultrasonics is to understand the physics of sound. Sound is vibration conducted from a vibrating or pulsing source. Sound is transmitted by all matter with variations in efficiency and speed depending on the nature of the matter and its environment. In general, solids are the best sound conductors …
The next series of blogs will explore ultrasonic cleaning in some detail. Today’s blog is an introduction to the world of ultrasound. The theory of sound was first defined and understood a little over 100 years ago when Lord Rayleigh published The Theory of Sound. Rayleigh was a Nobel Prize winner and, was also responsible for a number of …
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 …
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 …
Some substrate materials are inherent particle generators and may never be cleaned to the point of there being no particles present. With these materials, particles are a way of life and can not be avoided. This, of course, makes cleanliness testing using particle analysis a difficult if not impossible task. The difficulty is exacerbated by …
Before we leave the subject of particles and particle counting, there are some things we need to touch on regarding “exceptional” particles. In an earlier blog, Particles That Don’t Count?, we discussed briefly some particles that may or may not count when it comes to analyzing the cleanliness of a part. These and several other kinds of …
In recent blogs we have been talking, for the most part, about particles that are relatively large – ones you can see, touch and feel. There is a world out there, however, that worries about particles that are very tiny. I’m talking about particles that are smaller than tens of microns in dimension. An earlier …
Now it’s time to see the results! Particles have been harvested, collected and are ready to either be weighed or counted. The first step in evaluating cleanliness using either method is to examine the specification. There are two basic types, part-specific and generic. Part-Specific Specifications – Part-specific specifications will state the sample size in number …
In preceding blogs we have talked about harvesting particles for evaluation and talked about specifications. Specifications may or may not dictate the harvesting process but almost always provide detail on how to evaluate the particles harvested in a process involving re-washing. The first step is to concentrate the harvested particles for evaluation. This usually involves a filtration and evaporation process. …
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 …
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