Polyurethane Caster Wheels
It's important to know that not all polyurethanes are equal – the material is available with a tremendous range of characteristics. During fabrication, manufacturers have many different chemical compounds to choose from, and various manufacturing processes which determine characteristics of the resulting products. They choose different polyurethane compounds, based upon the intended application situation. Is it important that the caster be non-marking, or make no audible noise? Will it be operated at low speeds or high speeds? Will it be used continuously, or only occasionally? Each of these situations may require a different polyurethane formulation.
Non-marking
– while often considered to be non-marking and floor protective, polyurethane casters function better in this regard on some floors than on other floors. They work well on hard surfaces such as ceramic tile, concrete, or hardwood – but usually are not suggested for use on linoleum, vinyl or soft wood floors. Neoprene may be a better choice for softer flooring materials.
Low-speed versus high speed
– as polyurethane casters roll, they flex as they load and unload while the caster is in motion. This constant loading and unloading causes internal heating in the polyurethane – and as speeds increase, so does the heating. If too much heat builds up internally, it can actually melt the polyurethane, leading to a failure called a "blowout". To avoid this problem, the manufacturer will formulate a polyurethane able to withstand the heat generated by higher speeds. This means that if you are looking for casters to be used in a towline operation, make sure you choose models rated for the speeds at which your equipment will operate.
Occasional versus continuous duty
– some polyurethane caster wheels, when under load and stationary (not moving) for long periods of time, may be prone to developing flat spots. To avoid this, manufacturers modify their compounds, and create polyurethane wheels that maintain their shape when loaded but not moving. If you need polyurethane casters for a heavy equipment cart that rarely moves, for example, be sure you choose casters that keep their shape.