Plastics Technology

OCT 2018

Plastics Technology - Dedicated to improving Plastics Processing.

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of the guide bushing. The bushing does not need to be keyed or oriented for the grease to travel into the internal grease grooves. What's a Zerk fitting? Oskar Zerkowitz immigrated to the U.S. from Austria and changed his name to Oscar Ulysses Zerk. He has more than 300 patents, one of which was a grease fitting known as "The Zerk." At the time of his death in 1968, it was estimated that 20 billion of these fittings had been manufactured. That was 50 years Diverse Feeding Solutions for Plastics Processing From polymers to fillers and additives Schenck Process has the most diverse loss-in-weight feeder line to precisely handle your materials. Whether it's a specific agitation method, throughput capacity or helix design, we will find the right solution to meter the most challenging dry materials for plastics compounding applications. Also, for pre- and post-extrusion dry material handling we offer complete pneumatic conveying packages and dry material handling solutions. Schenck Process LLC 7901 NW 107th Terrace Kansas City, MO 64153 816-891-9300 sales-fcp@schenckprocess.com www.schenckprocess.com/us ago. I wonder what that number is up to today. But to give credit where credit is due, it was Arthur Gulborg at the Alemite Die Casting Co. who invented the first hollow grease fitting with a spring-loaded ball in 1916. In 1924, Alemite purchased the Allyne-Zerk Co. and continued to manufacture both grease-fitting versions. In 1933, Joe Bystricky invented a modified version that is basically the style still used today. For whatever reason, Oscar Zerk's name remains associ- ated with this unique device. Several mold-supply companies offer self- lubricated guide bushings, which are plugged with graphite. Graphite is an allotropic form of carbon. As the ejector plates move, traces of the graphite cover the surface of the guide pin. These bushings work well, particularly in medical or food-contact appli-cations where external lubri- cants are prohibited. But if the molding material produces any corrosive outgasses, the longevity of these self-lubricated bushings can be compro- mised. And if the bushings are ever lubricated with grease or oil—out of sheer habit—their longevity will also quickly diminish. Just make sure to use the appropriate diameter and quantity of guided ejector bushings—self-lubricating or Surface Roughness Averages Micro inches (μ in.) 500 250 125 63 32 16 8 4 2 Microns (μ) 12.70 6.35 3.18 1.60 0.81 0.41 0.20 0.10 0.05 Drilling Reaming EDM (Sinker) EDM (Wire) Grinding Honing Polishing Lapping @plastechmag 39 Plastics Technology T O O L I N G

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