Metal or plastic? It is the first fork in many product programmes, and the honest answer is 'it depends' — on five specific things. This Q&A works through them. Our comparison guide covers the three-way picture including CNC machining; this piece stays on the two moulding processes.
Die casting forces molten metal — in this factory, aluminum alloys ADC12 and A380 (and zinc) — into a steel die under high pressure. Injection moulding forces molten plastic — here, ABS and PP — into a mould. Both are 'buy tooling once, produce fast' processes; they differ in material, and almost every downstream difference flows from that word. Metal brings stiffness, heat resistance, shielding and a premium hand-feel. Plastic brings electrical insulation, corrosion immunity, integrated snap features, colour-through material and lower weight.
Our factory runs both — the aluminum die casting division and the plastic injection parts range — so the answers below are not a sales pitch for either side. They are the routing logic the DFM review applies when a drawing could go either way.
A die cast aluminum part is, part for part, stronger and stiffer than an ABS or PP moulding of the same geometry — that is simply metal versus plastic. But strength is a requirement, not a virtue: a handheld enclosure that survives its drop tests in ABS gains nothing from being cast in aluminum except weight and cost. Conversely, a structural bracket, a heatsinking housing or a part that must hold threads under repeated load may be unbuildable in plastic at any reasonable wall thickness.
The productive question is not 'which is stronger' but 'what loads, temperatures and abuse must this part survive — and what does the cheaper material need (ribs, inserts, thicker walls) to survive them?' Metal inserts in plastic mouldings are a legitimate hybrid answer, and a factory that machines metal and moulds plastic can produce the hybrid as one part family.
Both processes front-load cost into tooling and reward volume with low unit prices, but the curves sit differently. Die casting dies are substantial steel tools built for very high shot counts under thermal and pressure punishment; injection moulds in this class of work are typically the lighter investment. Per part, metal raw material costs more than plastic resin, and die cast parts often need trimming and sometimes machining, while mouldings frequently emerge complete.
The crossover logic is identical to the one in our die casting vs CNC machining guide: estimate lifetime volume honestly, price tooling plus unit cost across that volume for each candidate process, and let the arithmetic speak. The trap is comparing one process's tooling against the other's unit price — a mismatch that makes whichever you looked at second seem absurd.
Three application factors routinely settle the question by themselves. Heat: a housing that must spread or shed heat — near power electronics, LEDs, motors — points to aluminum, which is why our heatsinks are metal extrusions; plastic insulates rather than conducts. Shielding: where EMI containment matters, a conductive metal enclosure does the work natively, while plastic needs conductive coatings or inserts. Environment: sustained outdoor, chemical or high-temperature exposure punishes plastics in ways metals tolerate, while salt-spray cosmetic expectations can punish bare metal — the finish system then decides, and finishes are a whole topic of their own.
None of these factors care about your tooling budget, which is why routing starts with the application and only then moves to cost. A cheap part that fails its environment is the most expensive part in the programme.
Frequently, yes — and many of the assemblies this factory ships do. A die cast base provides structure and heat spreading; a plastic enclosure provides the insulated, colourful, snap-together shell; machined metal inserts provide thread strength where screws land. The custom plastic enclosure business exists substantially to close over metal internals. When both sides are produced in one plant, the moulding is sampled against the real casting, shut-lines are verified on hardware, and the 'plastic versus metal' debate resolves into 'plastic and metal, each where it belongs'.
If your programme is at the fork, send both candidate drawings — or the one drawing and the question. The review will route it with the reasoning visible, including the option you did not ask about. That is the entire point of asking a multi-process factory.
Whichever way you are leaning, the fastest first enquiry contains: the drawing or a clear photograph and dimensions if no drawing exists yet, the application's environment and loads in plain words, the finish and appearance class, and honest quantities — trial, first year, lifetime. With those four, the metal-versus-plastic question usually answers itself inside one review, and the answer arrives with a price attached instead of an opinion.
Tell us the material grade, quantity and finish you need for your project. Our engineers review every drawing for die casting, machining or stamping feasibility before quoting — no obligation.
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