About the wheel material
PP: easily burning, with slight plastic smell, melting evenly, with ropiness.
PA: difficulty burning, with hair burning smell, blistering on the surface, with ropiness.
HTPA: same phenomenon with PA, with white powder substance on the surface.
PU: easily burning, with slight white smoke, easily melting, with ropiness.
PVC: easily burning, with strong dark smoke, without ropiness, with black carbon powder on the surface.
