How it is attached to equipment, furniture, etc. Amount of use. Environmental conditions, such as extreme temperatures or moisture, and exposure to chemicals, salt, oil, etc. Shock loading and other physical impacts. Noise when caster is in operation.
Wheel type is another major consideration.
Casters are available in numerous wheel types and materials. Ball casters swivel easily and roll smoothly on carpet and hardwood floors. Wide wheel casters spread weight over a broader floor area, and are thus less likely to mar softer floor surfaces. Conventional wheel casters combine maneuverability and ease of maintenance within a full range of duty ratings. Your choice of wheel material should correspond with the type of floor surface and application.