What counts as an automotive stamping part?
Automotive stamping covers everything from a car body panel weighing several kilos to a terminal inside a connector housing weighing less than a gram, and the two are made on completely different equipment. The parts an automotive supplier buys from a contract stamper, rather than from a press shop inside a vehicle plant, are the small and mid-size functional parts: terminals, clips, brackets, shims, connector shells, sensor housings, valve housings, motor end caps and heat shields. These are produced on progressive dies, transfer presses or deep-drawing tools, usually between 25 t and 350 t, in volumes from tens of thousands to several million pieces a year. What makes them automotive parts rather than general stampings is not the shape — it is the documentation, the change control and the process capability that the programme demands.
The part families we run
- Terminals and contact parts — copper, brass and copper-alloy strip, usually progressive die, with plating and a controlled burr on the mating faces.
- Clips, retainers and spring elements — 65Mn and 301 spring steel, where the spring rate or the retention force is the functional dimension.
- Brackets and mounting plates — zinc-plated or phosphated steel, blanked and formed, frequently with pressed ribs for stiffness.
- Sensor housings — deep drawn 304 and 316L stainless, or DC04 with plating, for wheel speed, coolant temperature, exhaust gas temperature, oxygen and pressure sensors.
- Valve and actuator housings — deep drawn shells for solenoid valves, fuel pressure regulators and fuel metering units.
- Motor end caps and covers — drawn and stamped caps where wall thickness and concentricity drive the assembly fit.
- Shims and spacers — thin blanked or ground parts that set end float and preload.
Progressive die, transfer press or deep draw
The press route is decided by the geometry, not by preference. A progressive die carries every operation — piercing, forming, bending, drawing, trimming and parting — in one tool, with the strip feeding from station to station, so the part leaves the press complete. It is the default for flat and lightly formed parts and the cheapest route per piece above roughly 50,000 pieces a year. A transfer press is chosen when the part is too large or too deeply formed to stay on a strip: the part comes off the strip after blanking and is carried between separate stations by a transfer mechanism. Deep drawing in a single or double-action tool is the route when the part is essentially a shell — a housing with a closed end and a drawn wall — and the calculation is a draw ratio problem rather than a blanking problem.
Key point
Send the drawing and the annual volume together. The same part can be a progressive-die part at 2 million a year and a transfer-press part at 200,000, and a quotation that ignores volume is a quotation that will be re-cut before the tool is finished.
Materials
- DC01, DC03 and DC04 cold-rolled steel — the standard for housings and formed parts. DC04 is the deep-drawing grade, used where the part needs a real draw ratio.
- EN 10139 / C290 and similar strip grades — for parts specified against a European automotive strip standard.
- 301, 304, 316L and 430 stainless — corrosion and temperature resistance. 304 and 316L for housings, 301 where the part is a spring, 430 for magnetic return paths.
- 310S heat-resistant stainless — exhaust-side sensor housings that see sustained high temperature.
- Copper, brass and phosphor bronze — terminals and current-carrying parts.
- 65Mn spring steel — clips, springs and shims that must hold a load.
- Aluminium 1050, 5052 and 6061 — weight-driven brackets and housings.
What the programme will ask for
A functional automotive part carries documentation with it. Expect a PPAP submission, with Level 3 the standard level for a new programme and the level we quote against by default; an IMDS material data sheet, where the assembly is declared in the customer's compliance system; material certificates traceable to the heat or coil; and inspection records covering the dimensional and geometric characteristics on the drawing. Quality management runs to ISO 9001:2015, with IATF 16949-aligned controls in place for the automotive programmes we serve.
Surface treatment, and what is subcontracted
Plating and finishing are part of the drawing, not an afterthought, because the coating specification often comes from the vehicle maker rather than from the immediate customer. We work to specifications such as zinc-nickel (Fe-ZnNi), zinc, phosphating, passivation and electropolishing, and to powder or wet painting where a finish is specified. Balford produces parts in its own plant in Zhuji, Zhejiang, and is straightforward about which steps are not done in-house: bulk heat treatment, wire-cut EDM, passivation, electropolishing, electroplating, phosphating, and powder or wet painting are carried out by qualified subcontractors, who are bound to confidentiality terms at least as strict as the customer's NDA and receive only the information needed for their process step. The subcontractor used for a specific part is named on request.
Tolerances, and the three things worth calling out
Stamped and drawn parts are inspected against the drawing, so the drawing is where cost is decided. Three call-outs do most of that work. First, the general tolerance block: if a functional dimension relies on the block rather than on its own tolerance, the process has to be tightened everywhere to guarantee it. Second, the burr condition: a sheared edge carries a burr, and if the assembly cannot accept one, the drawing needs to say so, since adding a deburring or fine-blanking step changes the tool and the piece price. Third, roundness, concentricity and wall thickness on drawn housings: a wall-thickness call-out that is tighter than the draw allows forces an extra annealing or ironing stage. Where a design needs a tolerance better than the process can repeat, the honest answer is to say so at the DFM stage rather than to quote it and find out at first article.
Balford has been building single-drawing dies since 2000 and has produced more than 4,000 of them. The plant covers 12,000 m2 with 500+ machines and 120+ engineering and production staff, and produces roughly 50 million parts a year. Drawings are reviewed and quoted, usually within 24 hours, with the DFM observations returned alongside the price so the tool is designed against a drawing that has already been checked for manufacturability.
Frequently asked questions
What is the difference between a progressive die part and a transfer press part?
In a progressive die the part stays attached to the strip and travels through the stations still connected, and it is cut free at the end. In a transfer press the blank is separated from the strip early and is then carried between separate stations by a transfer mechanism. The progressive route suits flat and lightly formed parts and is the cheaper option above roughly 50,000 pieces a year. The transfer route suits parts that are too large, too deep or too awkward to move along a strip, and it lets a drawn feature be formed in a dedicated station.
Can you supply PPAP documentation for an automotive programme?
Yes. PPAP Level 3 is the standard submission level for a new programme and the level we quote against by default, and the pack is built from the drawing plus the inspection records taken at first article and through the run. Alongside it we supply material certificates traceable to the coil or heat, and an IMDS material data sheet where the customer's compliance system requires one. Quality management runs to ISO 9001:2015 with IATF 16949-aligned controls for the automotive programmes we serve.
Which parts are not economic to produce with us?
Very large body panels, parts wider than the press bed or needing more than 350 t of press force, and deep-drawn housings above a 250 mm draw diameter are outside the envelope, and we say so before quoting rather than after. Parts that are essentially turned or milled with no stamped feature are also better placed with a machining supplier. If a drawing sits outside these limits, a quick review will tell you in a day rather than a week.
How do you handle a part that needs plating as well as stamping?
The coating specification is treated as part of the part. Where the finish is electroplating, phosphating, passivation or electropolishing, the work is carried out by a qualified subcontractor with the surface condition controlled between the press and the finishing step, and the subcontractor is bound to confidentiality terms at least as strict as the customer's NDA. The subcontractor used for a specific part is named on request, and the process route is stated in the quotation, so there is no question later about where the parts travelled.