When I tell people at cocktail parties that
I have finally decided to answer that question.
Well, it seems that most companies that perform milling or grinding have a vital interest in the size and distribution of the resulting particles. These include companies in the fields of Pharmaceuticals, Chemicals, Mining, Building Materials, Food Processing to name a few.
Soooo.... there really is a significant need for particle-size analysis.
How is this accomplished? The most economical and easiest method is to utilize a series of sieves,
Standard test sieves, which are made of woven wire mesh, can work to sizes down to the 25 micron range -- smaller than a human hair. As wire mesh sieves reach their limits, sieve mesh made with the Electroforming Process may be needed. (Electroforming is a process for fabricating high-precision mesh by electro-deposition in a plating bath.
Some powder materials and small particles are difficult to separate. In these cases, particle-size distribution analysis calls for sophisticated shaking or separation methods such as ultrasonic vibrating or vacuum sieving.
After the capabilities of mechanical sieving have been exhausted, one of the new measuring methods available is Particle Sizing by Laser Diffraction. In a recent article, Bryn McDonagh of ATA Scientific did a magnificent job of describing this highly complex technique.
“Laser diffraction has become one of the most commonly used particle sizing methods,
Laser diffraction is often the method-of-choice when particles are very small or hard to separate mechanically.
If the test material can be separated mechanically and the particles are within the size ranges of wire or electroformed mesh, sieving provides the most economical approach by a wide margin. Sieve testing is easy to administer and requires little training.
Bottom line: If sieving will work, use it. Otherwise, you need to consider more elaborate processes such as Laser Diffraction.
Now that I have prepared this discourse, perhaps I can get more people at cocktail parties excited about Particle Size Analysis.
Thanks for listening,
P.S. How do you do your particle size analysis?