I'm going to have an online machine shop build a part for me using a CAD drawing that I specify.

Typically, these parts are made of aluminium, but this manufacturer also mills parts out of these plastic materials:

  • Polypropylene (PP)
  • Polystyrene (PS)
  • High impact polystyrene (HIPS)
  • Acrylonitrile butadiene styrene (ABS)
  • Polyethylene terephthalate (PET)
  • Polyester (PES)
  • Polyamides (PA) (Nylons)
  • Poly(vinyl chloride) (PVC)
  • Polyurethanes (PU)
  • Polycarbonate (PC)
  • Polyethylene (PE)

Polypropylene, I know, is the plastic used in water bottles, so I know that is not what I want.

This fabricated part will be used for the clutch cover on a motorcycle transmission and will have a raised section that needs to be tapped to allow attaching a gear shifter to, like in the aluminium version below.

Clutch Cover with Shift Mount

I'd like something rigid and strong. Plexiglass comes to mind, but there could be a better alternative that I am unaware of, as long as I am not getting into something exotic that would cost more than aluminium.

Could suggest a good plastic for me, which would need to be oil resistant and withstand typical engine transmission temperatures.

Location on Transmission

  • $\begingroup$ I have cut back the question to it's actual core of what has been asked. That you ended up using aluminium like the answer suggested is nice, but it is superfluous information for the actual question. As such the 'update' actually kind of invalidates the answer, which is strongly discouraged on our site. $\endgroup$ Commented Oct 31, 2018 at 12:54

2 Answers 2


Most plastics consist of linear molecules with little inter-molecular interactions, so most plastics melts too easy. The only ones you mentioned having a chance are polyuretanes and polyamides. They have (CO)(NH) fragments, that forms strong intermolecular hydrogen bonds. So, they are ones of the strongest polymeric materials

And I will recommend aluminum anyway as it is much harder to screw things with aluminum.


Glass filled nylon molds well, wears well and is most resistant to heat with regards to the plastics you mentioned


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