Problematic use of plastic housings
Plastic housings can only withstand aggressive environments to a certain extent before failure occurs due to swelling, brittleness or fatigue from high mechanical forces, with all the negative consequences for production and associated costs.
Problematic use of gray cast iron housings
Grey cast iron housings can withstand higher forces, but rust in aggressive environments and cannot be used in food processing applications due to hygiene regulations.
Problematic use of bearings made of stainless steel (e.g. bearing SUC 210)
High price, limited load capacity (softer, stainless steel; high wear) and the only protection from the environment is a seal on the bearing itself. The only advantage: Food grade in combination with food grade grease.