PPG manufactures powder coatings for various applications and industries. They have a new product line designed specifically for one new customer.


Over-sized particles are getting mixed in with the final product instead of being screened out by the Rota-Sieve. These oversize particles are adversely affecting the finish and causing blemishes in the powder coating. This problem has not been seen before, even on material being run on screens of same fineness (as fine as 200 mesh). This issue does not appear to be caused by either the chemistry of the new product or the process leading up to the Prater sifter. Time is critical as this problem has the potential to threaten a global opportunity for PPG with this new customer/product.


Service techs were all booked up, and were not available to get out to the customer as fast as was desired. PPG wanted someone on site to help them find a solution. Arrangements were made to send a customer service representative who was familiar with the equipment out to PPG that same night. The following morning after meeting with all the responsible personnel at PPG, and being given a quick tour of the facility to see their process, the Prater customer service rep went out onto the production floor to examine the equipment. It became readily apparent that over the years the fit of certain parts had gotten sloppy and some pieces were moving around and allowing the oversize particles to slip by between the worn parts and into the good product. Suggestions were made to use additional gaskets to take up the slop until new parts could be ordered. PPG had also requested a design change to act as a secondary preventative measure against this happening again. This ended the trip to PPG but there was still more to do. Upon return to Prater and evaluating the parts involved for PPG the engineering team discovered a design issue that had never caused a problem before.

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A unique part number was created for PPG to satisfy their need. As a result of looking into this issue and redesigning a part a revision was made to improve all the sifters being produced from that point forward. The customers problem was solved and Prater Rota Sieves were improved.