Food-grade Bearings: Proper Material Selection for Health and SafetyJune 17, 2019
Here’s a tough mandate to solve. In an industrial setting, a set of bearings can be porous and packed with grease. Shifting this scenario so that the mountings are situated inside a food-grade equipment frame, those normally beneficial features assume application-deleterious proportions. The regulations protecting the equipment can’t permit just any old grease type, nor can they allow a material type that could soak up globs of bacteria-transporting oils.
A Two-Pronged Oxidization Assault
Special challenges come to the fore when equipment designers select food-safe bearings. Already done with the rest of the system, glossy stainless steel sheets and hose-down protected housings are in place. Focusing now on the moving parts, the material build of the system bearings requires an overhaul. First things first, what are the threats? Well, the food could be loaded with acids or oxidizing compounds. A vinegary solution flows along one food prep line while acidic animal juices drip on a second line. If those juices penetrate a bearing, the alloy races and rolling elements will corrode. Then there’s that hose-down operation to worry about. If the water gets into the bearings, the same oxidizing action is inevitable. To counteract those corrosive forces, the bearings need a rust-proof feature.
Food-Safe Bearing Material Selection
An obvious solution is being overlooked. Removing corrosion-prone alloys from the equation, hard plastics and ceramics take over. They’re designed to handle light-to-moderate loads, which is about as heavy as a light production run ever becomes in food-safe applications. Of some interest here, newer polymer bearings and bushings feature self-lubricating attributes. Ceramics are next, with their heat-resistant components providing improved rolling efficiency, even when thrust loads impact the moving parts of food carrying machine assemblies. Better than those polymers and ceramics, stainless steel bearings eliminate corrosion. They’re also dense, so porosity-hiding contaminants have no place to conceal their microscopic forms. Of course, to create an optimally designed bearing, there’s no reason to limit the solution to any one of these materials.
That last sentence is loaded with latent implications. Sure, a dense nickel-composite alloy will provide a high-quality, food-safe material build. Electroplated or specially coated, the rings and rolling elements lack microscopic flaws, so bacterial impurities can’t gain any purchase whatsoever. That feature also stops food acids and washdown chemicals from acting as metal oxidizers. What about the entirely corrosion-proof ceramics and plastics? By using some out-of-the-box thinking, the ideal solution becomes clear. Instead of using an either/or approach, a system designer opts for a composite product. Corrosion proof, bacteria proof, and load capable, stainless steel races and ceramic rollers deliver best-of-both-worlds advantages.
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