Metal 3D printing or plastic: when the premium is not worth it

A share of the enquiries we get start with: we need this part in metal. After two questions about the application it often turns out that metal is not the requirement, stiffness, temperature resistance or dimensional stability is. Those are requirements, not materials.

What metal 3D printing actually costs

Metal powder bed processes need shielding gas, powder handling, heat treatment and usually finishing on a mill. That process chain turns even small parts into four figure line items, and lead times rarely fall below two weeks. For a part that covers a housing or holds a line, that is hard to justify.

FDM in engineering materials typically lands an order of magnitude below that for the same application, with lead times from 24 hours to a few days. The honest comparison is therefore not metal against plastic, it is requirement against cost.

Where fiber filled plastic is enough

• Brackets, consoles and mounts with moderate static loads: PA12-CF is stiff, dimensionally stable and light.
• Covers, housings and shrouds: ABS, ASA or PC depending on temperature and weathering.
• Fixtures, gauges and nests: PA12-CF and PETG-CF, far faster than machined aluminium.
• Grippers and end of arm tooling: mass at the flange is an advantage here, not a compromise.
• Legacy and spare parts that used to be metal but were never highly loaded.

In these parts the material is not the bottleneck. Wall thickness, ribs along the load path and orientation in the build decide the outcome. A properly designed PA12-CF part replaces a machined aluminium bracket in many cases with no operational downside.

Where metal stays

• Continuous temperatures well above 120 degrees, for example near exhaust or heating systems.
• High contact pressure, press fits and bearing seats without a bushing.
• Safety relevant load bearing parts requiring proof or certification.
• Wear points with metal on metal contact and lubrication.
• Parts with tolerances below roughly 0.1 mm across larger lengths.

In those cases we say so plainly. Printing a part that fails in service helps nobody, and a printed sample does not replace a structural calculation.

The practical middle path

Often the best answer is a hybrid. Printed structure, metallic functional faces: brass threaded inserts for load bearing bolted joints, steel bushings at bearing seats, inserted plates where contact pressure occurs. The part stays light and quickly available but behaves like metal where it counts.

If you are unsure, send the STEP file with load, temperature and environment. We will tell you whether FDM covers the requirement and cost both routes, instead of simply selling the process we happen to run.