Although cast-iron wheels are virtually indestructible and are able to withstand the highest loads, their use in the food industry is not recommended (not acceptable), because they are prone to general corrosion of the caster components and because of the damage which they do to floor surfaces. Floor surfaces may break up, if wear is allowed to progress. Damaged floor surfaces then become an excellent harbor for contaminants and microorganisms.
Zinc-Plated Mild Steel Casters
Casters manufactured from zinc-plated mild steel should be avoided. When the zinc coating on the wheels wears away, corrosion will occur quickly, which may result in increased friction between the wheels and the caster forks (horns). Casters manufactured from zinc-plated mild steel require the swivel bearing to remain lubricated to prevent it from corroding. If corrosion of the swivel bearing occurs, it will prevent the caster from swiveling efficiently; as a consequence increased side loads will be applied to the caster components, which can result in premature failure of the caster. Zinc-plated mild steel casters with different types of swivel bearing seal arrangements are available that allow lubrication-in-place, and that prevent contamination of the bearing and loss of lubrication during the cleaning of the process equipment. But if lubrication is not regularly and properly done, corrosion and increased play still will be observed in these swivel bearings, with the result that, after a certain time, the caster will start to squeak until it stops swiveling again.