Materials for Robot Enclosures: How to Choose
Material choice is a process choice. Pick the family first, then the route that can hold it.
Short answer: start from what the part has to survive — impact, UV, heat, a person's hand — then pick the family, then the process that can hold that family.
| Family | Strength | Watch out for |
|---|---|---|
| Aluminium alloys | Stiffness per weight, stable on machining | Corrosion if unprotected; anodise or paint |
| ABS | Impact resistant, easy to paint | Pale under UV unless stabilised |
| PC and PC/ABS blends | Higher heat, good clarity | Stress cracking against some chemicals |
| Filled PA | Stiffness, low friction at joints | Absorbs moisture; dimensional drift |
| Engineering plastics, moulded | Production-grade at volume | Needs tooling, so process changes |
The three questions that narrow it
Will it see sunlight? An unpigmented ABS yellows. A UV-stabilised grade or a PC blend holds colour longer, which matters for any cover on a machine that stands in a room with windows.
Who touches it? A cover a person handles benefits from a soft-touch overmould, which is cast in the same programme as the rigid shell beneath it. A part nobody touches should be optimised for stiffness and cost instead.
What heat does it sit near? Motor housings and power electronics push the local ambient up. A PC blend tolerates more than ABS, and the grade is cheaper to specify correctly once than to re-quote later.
Material and process are coupled
Naming a material is a process decision, not just a purchasing detail. Casting runs on two-part polyurethane systems, whose shrinkage and demould behaviour come from the supplier's technical datasheet — Covestro and its peers publish these per grade. Moulding runs on thermoplastic grades that are specified against ISO 294 test specimens, so a quoted property is traceable to a standard rather than to a sample. A specific production grade can therefore rule out casting entirely, and it is cheaper to know that before the mould is made.
Surface treatment follows the material
Finish is specified, not described: painting, sandblasting, polishing, silk-screen and texture all behave differently on each family. Injection-moulded and cast faces are graded on the VDI 3400 scale, machined faces on ISO 1302 roughness grades. Sending a physical sample is faster than describing the surface in words, and it removes ambiguity from the quotation.
Which material suits an external cover?
A UV-stable ABS or PC blend if the part will see sunlight, a filled PA if it needs stiffness, and a soft-touch resin where it is touched by hand. Paintability and impact resistance usually decide it more than raw strength.
Can a material change the process route?
Yes. A specific production grade may rule out vacuum casting, because casting runs on two-part polyurethane systems while moulding runs on thermoplastic grades specified against ISO 294 test specimens. Naming the grade early avoids re-quoting.
How is material verified on delivery?
With a material certificate against the grade and lot. Certificates are available on request, and the inspection chain runs alongside the dimensional report.
Also read: the materials and surface finishes page and what a quotation needs.
Send the drawings, get a DFM view back
Rocky Chen replies with a process route, the tolerance risks we see in your data and a quotation — usually within one working day.