Materials
What we cut, and what to watch for.
The materials and finishes we work in most often, each with the practical note an engineer would actually want — not just a list of names.
Metals
Aluminium
| Grade | Typical use | What to watch at DFM |
|---|---|---|
| 6061-T6 | General structural, brackets, plates, chambers | Thin walls move after roughing — allow a stress-relief step |
| 6082-T6 | Structural, common in Asia-Pacific supply | Similar to 6061; confirm which your drawing actually requires |
| 7075-T6 | High-strength structural, aerospace fittings | Stronger but less corrosion-resistant; usually needs a finish |
| 5083 / 5052 | Marine, weldments, formed parts | Poor for fine threads; better in fabrication than in tight tolerance work |
| MIC-6 cast plate | Flat tooling plate, optical and jig bases | Excellent stability and flatness; not for structural loads |
Stainless and steel
| Grade | Typical use | What to watch at DFM |
|---|---|---|
| 304 / 304L | General corrosion resistance, fixtures | Work-hardens; deep small bores are slower than they look |
| 316 / 316L | Fluid hardware, medical, marine, semiconductor | The default where cleanliness and corrosion both matter |
| Duplex 2205 | Energy, high-strength corrosive service | Tough to machine; expect longer cycles, priced honestly |
| 17-4 PH | High-strength components, shafts | Machine before ageing where the tolerance allows |
| 416 / 430 | Free-machining and magnetic applications | Lower corrosion resistance than 300 series |
| Mild steel (1018, EN8) | Fixtures, jigs, non-critical structure | Cheap and predictable; needs protection from corrosion |
| Tool steel (D2, O1, A2) | Wear faces, locators, punches | Grind after heat treat — allow stock and a longer route |
Alloys and specials
| Material | Typical use | What to watch at DFM |
|---|---|---|
| Titanium Gr 2 / Gr 5 | Aerospace, medical, corrosion service | Slow removal and tool cost dominate the price |
| Inconel 625 / 718 | High temperature, energy, aerospace | Expect long cycles; confirm grade before quoting |
| Hastelloy C-276 | Severely corrosive service | Difficult to machine; price reflects reality, not optimism |
| Monel 400 | Marine and chemical hardware | Gummy; needs the right tooling and feeds |
| Copper / brass / bronze | Electrical, bushings, wear parts | Copper is soft and burrs readily — deburring is a real step |
Engineering plastics
| Material | Typical use | What to watch at DFM |
|---|---|---|
| PEEK | Semiconductor wafer contact, high-temp insulators | Expensive stock; nesting matters to the price |
| PTFE | Seals, chemical service, insulators | Creeps and moves under clamping — needs a datum strategy |
| Delrin / acetal | Bushings, rollers, general machined plastic | Dimensionally stable and predictable; the easy one |
| UHMW-PE | Wear strips, guides | Not for tight tolerance; moves with temperature |
| Polycarbonate / acrylic | Guards, windows, enclosures | Stress-cracks if machined hot or clamped hard |
| G10 / FR4 | Electrical insulation, structural laminate | Abrasive on tooling; dust needs containment |
Finishes
Surface finishes, and where they go.
| Finish | Applies to | Note |
|---|---|---|
| As-machined | Everything | Ra 0.4 µm achievable as standard, verified against callouts |
| Deburred, edge-broken | Everything | Part of the route, not an extra. Critical for anything going into a clean environment |
| Bead blast | Aluminium, stainless | Uniform matte cosmetic finish; masks tool marks |
| Anodising, Type II | Aluminium | Corrosion and wear resistance, colour available. Subcontracted |
| Anodising, Type III (hard) | Aluminium | Thicker and harder; grows the surface, so allow for it in the tolerance |
| Chemical conversion (Alodine) | Aluminium | Conductive and corrosion-resistant. Subcontracted |
| Passivation | Stainless | Restores the oxide layer after machining. Common for semiconductor and medical |
| Electropolishing | Stainless | Improves finish and cleanability; slightly reduces dimensions |
| Nickel or zinc plating | Steels | Corrosion protection. Subcontracted; adds thickness |
| Heat treatment | Steels, aluminium | Subcontracted. Grind after, where the tolerance requires it |
| Laser marking | Most metals | Part numbers and traceability marks |
Coatings and heat treatment go to qualified subcontractors, named on the quote rather than hidden behind a line item. Anything that grows or removes surface needs to be accounted for in the tolerance — we raise that at DFM.
Questions
About material and finish.
Can you machine a material that is not on this list?
Usually. This is what we cut most often, not the limit. Send the grade with your RFQ and we will confirm availability and machinability before quoting rather than after.
Can I free-issue material?
Yes. We inspect it on receipt against your drawing and tell you before cutting if what arrived is not what the drawing expects — wrong temper, wrong size, wrong certificate.
Do finishes get applied in-house?
Anodising, plating and passivation go to qualified subcontractors, named on the quote. Deburring, bead blasting and surface improvement are part of the machining route. Either way the finish is inspected here before the parts are cleaned and packed.
Which finishes are safe for a clean environment?
Ask before specifying. Some finishes shed, some trap contaminants in porosity, and some are incompatible with the cleaning procedure. This is exactly the sort of thing the DFM review catches, and it is cheaper to catch there than at incoming inspection.