Why are rolled threads stronger?

The metal is pressed into shape rather than cut, so the grain follows the thread form and the root is work-hardened and smooth. This gives noticeably better fatigue strength than a cut thread.

What blank diameter is used for thread rolling?

Roughly the pitch diameter of the thread, which is less than the nominal size. The exact blank size is set by the rolling shop for its dies and the thread class.

Can hardened steel be thread rolled?

Up to about 40 HRC, with suitable dies. Harder parts are usually rolled before heat treatment, or the threads are ground.

Thread rolling job work: strength, sizes and cost

Thread rolling forms a screw thread by pressing hardened dies into a round blank, so the metal flows into the thread shape instead of being cut away. Rolled threads are stronger, smoother and very fast to make, which is why most bolts, studs and screws have rolled threads.

Quick facts

Process: Cold forming between flat or round dies
Blank diameter: About the pitch diameter of the thread, not the major diameter
Strength: Higher fatigue strength than cut threads (unbroken grain flow)
Materials: Ductile steels, stainless steel, brass, aluminium; up to about 40 HRC
Speed: Seconds per part
Usually priced: Per piece or per 100 pieces

Rolled or cut threads?

	Rolled	Cut (turned or tapped)
Strength	Higher, especially fatigue	Normal
Surface finish	Smooth, burnished	Machined
Speed	Very fast for batches	Slower
Material waste	None	Chips
Best for	Bolts, studs, screws in quantity	Few parts, hard materials, large threads

What to know

The blank is turned to roughly the pitch diameter; the thread rises above it
Material must be ductile enough to flow; very hard or brittle materials crack
Threads close to a shoulder may need a cut thread or an undercut
Knurling is a related process that rolls a straight or diamond grip pattern

What to send

Thread size, pitch and class (e.g. M12 × 1.75, 6g)
Material and hardness
Thread length and how close it runs to a shoulder
Blanks supplied by you, or made by the shop
Quantity

Need thread rolling done?

Post your requirement free. Workshops that take your kind of work see it and get in touch. You only talk to the ones that fit.

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Related job work

Machines

Materials

Questions

Why are rolled threads stronger?: The metal is pressed into shape rather than cut, so the grain follows the thread form and the root is work-hardened and smooth. This gives noticeably better fatigue strength than a cut thread.
What blank diameter is used for thread rolling?: Roughly the pitch diameter of the thread, which is less than the nominal size. The exact blank size is set by the rolling shop for its dies and the thread class.
Can hardened steel be thread rolled?: Up to about 40 HRC, with suitable dies. Harder parts are usually rolled before heat treatment, or the threads are ground.

The figures on this page are typical values for guidance, written by Diemeco from standard engineering practice. They are not a specification: confirm grades and properties with the relevant standard or the supplier's mill test certificate, and tolerances with your workshop. Last checked 15 October 2026.