Custom machining for automotive, EV and autonomous programmes
Vehicle work moves fast at the front and slow at the back: a bracket is revised three times during validation, then the same part must run unchanged for five years. The process has to survive both phases.
Part families we run
ADAS brackets carry a sensor whose alignment is calibrated in software, but the bracket still has to hold the sensor within a mechanical window across temperature and vibration. Hole position and face flatness matter more than the bracket's own dimensions.
CV joint adapters, coupling flanges and motor-to-gearbox adapters. The bolt circle and the pilot diameter decide whether the joint runs true; the rest of the part is general tolerance.
Cam gears, crank gears and timing gears in 4140 or 42CrMo, heat treated to 48–55 HRC. Machining leaves grinding allowance where the tooth form must be corrected after hardening.
Reducer housings and motor covers with a gasket groove or an O-ring face. Groove depth tolerance controls seal compression, which is why it is the one callout worth tightening.
Aluminium heat sinks with milled fins, and interior or exterior trim where anodized colour has to match across a batch. These two requirements pull in opposite directions on cost.
Materials and finishes for vehicle parts
| Part | Material | Finish | Why |
|---|---|---|---|
| Sensor bracket | 6061-T6 | Black anodize | Light, stable, non-reflective |
| Drivetrain flange | 4140 or 42CrMo | Black oxide + oil | Strength, wear, moderate corrosion |
| Timing gear | 42CrMo | Heat treat 48–55 HRC | Tooth wear resistance |
| Housing | ADC12 die cast + machined | Powder coat | Volume shape, machined sealing face |
| Trim | 6063 or 6061 | Anodize, dyed | Colour consistency, corrosion |
| Heat sink | 6063-T5 | Clear anodize or chromate | Thermal path, corrosion |
Where automotive parts go wrong
A bracket where every face carries 0.05 mm goes through extra operations for no assembly benefit. Two functional faces and four general ones behave identically and cost less.
Hardening 4140 after the bores are finished moves them. Either rough, harden and finish, or accept a grind operation afterwards. The drawing should imply which.
Groove depth and width are derived from the gasket cross-section and target compression. Without that data the machinist guesses, and the leak test finds out.
Two orders months apart in the same colour rarely match. If the customer compares them side by side, they must be produced as one lot.
Industry questions
Yes. The part is machined with grinding allowance where needed, heat treated under a controlled supplier, then finished or ground. Hardness is checked on a sample from the batch and reported.
A scope is agreed at RFQ: dimensional results, material and finish certificates, and process flow. A full PPAP element set is rarely justified for a prototype or pilot build, so the scope is set before the order rather than after.
The program, fixture and inspection plan are stored against the part number. A repeat order runs the same route, and if a fixture is remade the first article is re-run and compared with the original report.
Yes. Send the target colour as a Pantone or RAL reference plus a physical sample if you have one, and the first batch is approved against it before the rest of the run is finished.
Send the bracket, flange or gear drawing with the heat treat and finish callouts.
Heat treatment and finishing change dimensions. Sending both on the drawing lets the process route carry the allowance instead of discovering it at fit-up.
From the shop notes
Longer answers to the questions these pages raise.