What Is Cold Heading? How Bolt Blanks Are Formed Without Cutting
Cold heading is the process that makes most of the world's bolts: a cut length of steel wire is struck repeatedly by dies, at room temperature, until its head and shank take shape. Nothing is melted and almost nothing is cut away — the metal is squeezed into its final form. If you have ever wondered how a plain coil of wire becomes a hex-head bolt with a formed head, rolled thread and consistent dimensions by the million, this is the process.
We cold-head custom fasteners in the M5–M24 range. This guide explains how the process works, why it produces strong parts, where its limits are, and how it honestly compares with the alternative of heating the metal first.
The process, step by step
- Wire is drawn to size. Production starts from coiled steel wire, drawn to the diameter the part requires. The wire's material — in our high-strength production, typically 40Cr alloy steel — decides what property class the finished bolt can reach after heat treatment.
- A blank is cut. A precise length of wire is sheared off. That blank contains exactly the volume of metal the finished part needs; there is no allowance for waste.
- Dies strike in sequence. The blank moves through a series of stations. Each die and punch strikes or presses it once, moving the metal a step closer to the final shape — gathering material where the head will be, then forming the head itself (hex, round, flange, or a special profile) while the shank keeps its diameter.
- The thread is rolled. After heading (and after heat treatment, where the class requires it), the thread is formed by rolling dies that displace the surface into the thread profile rather than cutting it.
- Heat treatment and finishing follow. For classes 8.8 and above, quenching and tempering develop the specified strength; the surface treatment — black oxide, zinc, colour zinc or Dacromet — is applied last.
Why cold-formed parts are strong
When metal is machined, the cutter slices across the steel's internal grain. When metal is cold-headed, the grain flows with the new shape — around the head, along the shank — instead of being cut. That unbroken flow, plus the work-hardening the material gains from being formed cold, is why a cold-headed blank is an excellent starting point for a high-strength fastener. The property class itself (4.8, 8.8, 10.9 or 12.9) is then delivered by material selection and heat treatment, as explained in our property class guide, and verified by testing.
Cold heading vs hot forging: the honest comparison
The alternative way to form a bolt head is to heat the blank first — hot forging. Neither process is "better"; they suit different parts.
| Cold heading | Hot forging | |
|---|---|---|
| Metal temperature | Room temperature | Heated until plastic |
| Typical size range | Small to medium (ours: M5–M24) | Medium to very large |
| Surface and dimensions | Clean surface, tight consistency across long runs | Scale on the surface; usually needs more finishing |
| Tooling | Precise dies per shape; economical across production volume | Dies also required; heating adds energy cost per part |
| Best for | High-volume bolts and formed shapes | Very large bolts, shapes beyond cold-forming loads |
Above the cold-heading range, or for shapes that would demand more forming force than cold metal allows, hot forging — or machining from bar, the route we use for M8–M64 custom bolts — takes over. Our guide to cold heading vs machining covers how that choice is made in the overlap range.
What cold heading can and cannot make
It does well: hex, round, flange and socket-style heads; collars and washers faces formed in place; stepped shanks; long production runs of the same shape with piece-to-piece consistency.
It does not do: cross-holes, milled flats, eccentric or asymmetric features — those need machining operations; diameters beyond machine capacity; and shapes whose metal flow would tear rather than form, which the technical review identifies from the drawing before tooling is committed.
Each new headed shape also needs its own die set. Where a part is new and no sample or existing tooling exists, a mold fee applies, quoted separately — one reason first inquiries should say whether a sample exists, as our quote checklist explains.
Common misconceptions
- "Cold heading is just hammering." The blows are precisely sequenced die operations, each moving a calculated volume of metal; the tooling design is the engineering.
- "Cold means weaker, because nothing was heat-treated." Cold refers to the forming temperature, not the final condition. High-class bolts are quenched and tempered after forming.
- "Any bolt shape can be cold-headed." Formability has real limits; pretending otherwise is how tooling money gets wasted. An honest review says no when the shape says no.
FAQ
Is cold heading the same as cold forging?
In fastener production the terms overlap: cold heading is the cold-forging process specialised for forming heads on bolts and screws, station by station.
Why is cold heading economical at volume?
Because the blank contains only the metal the part needs — almost nothing becomes scrap — and the forming itself is fast and repeatable once dies are set. The die cost is real but one-time, which is why our minimum order for custom production is 2,000 pieces.
What sizes can HyHaven cold-head?
M5–M24. Larger or more intricate custom bolts are machined on our M8–M64 line. Send the drawing through the custom fasteners page and the review will route the part to the process that fits it.
HyHaven manufactures custom fasteners by cold heading (M5–M24) and machining (M8–M64), to your drawing or sample, from 2,000 pieces. Request a quote.