Problematic use of plastic housings
Plastic housings can only withstand aggressive environments to a degree, until failure occurs due to swelling, brittleness or fatigue due to high mechanical forces, with all the negative consequences for production and the associated costs.
Problematic use of gray cast iron housings
Gray cast iron housings can withstand higher forces, but rust in aggressive environments and cannot be used in food technology due to hygiene regulations.
Problematic use of bearings made of stainless steel (e.g. bearing SUC 210)
High price, limitation when absorbing forces (softer, stainless steel; high wear) and the only protection from the environment is only provided by a sealing washer on the bearing itself. The only advantage: Food-safe in combination with food-safe fat.