Generally speaking,common caster material is PU,PVC,TPR ,rubber ,nylon,PP,cast iron,phenolic and so on .How to choose suitable caster ? It depends on material characteristics and where you plan to use them ( market requirements and customer perference).
Below material characteristics for your reference,so you can know how to choose it.
(1)the PU and PVC ,PU is short for polyurethane and PVC is short for polyvinyl chloride.
they are the most common castors,low price with good quality.to make it easier to understand,you can think them as similar material,just the PU is more wearable and a little higher cost .
PVC caster is cost effective ,it will be your best choice if you want to control budget and both of them are good for all floors : tiles,hardwood,rough concrete,etc.
Furniture caster,small light duty caster,medium duty caster,heavy duty caster, PVC and PU caster are popular.
(2)TPR and rubber,both are soft material which means they rolls silently on hardwood ,tile floors or other place that you require it to be noiseless,such as hospital , laboratory and so on.
Widely used for hospital furniture caster,medical caster wheel ,heavy duty caster,high end commercial euiqpment ,etc.
(3)Nylon and PP, as you know these caster wheel tread is hard ,high load capacity and greater wear resistance
heavy duty caster,extra heavy duty caster or industrial trolley wheel will choose nylon caster.
(4)Cast iron,it is obvious that cast iron is steel and strong enough,it can bear high temperateure and support heavy duty and extra heavy duty load capacity,but the cart iron wheel is heavier.
(5)Phenolic,it is special high temperature caster,they can bear 180 degree,280 degree or even more.
Bakery equipment ,oven or other high temp environment will require these wheels.