Rollers in plasic, polypropylene, stainless steel or aluminium
These are popular for very lightweight conveyors, and in particular for food applications, or where a mild-steel roller might scratch or mark the surface of the carried product.
They are - of course - relatively fragile compared to the sturdier steel or polypropylene rollers. However, for loads of a few dozen kilograms, they are emminently suitable.
Plastic rollers can feature all of the different shaft permutations that steel rollers can, including sprung loaded, threaded, and flattened-D configurations.
They can have all of the same shaft types as standard steel rollers
They can have the same shaft configurations as the standard steel rollers
A Polyprop roller is VERY tough; even moreso than its steel equivelant. This is because is is a solid roller, rather than the hollow tubes of its steel or plastic brethren. It is also heavier as a consequenceIt is - however - a speciality item, requiring individual machining, and is very expensive as a result. If, however, you want a tough, long-life roller, then this is the one to have !