Almost every screw used in series assembly – in furniture, appliances, electronics or vehicles – starts as a coil of wire. Cold forming and thread rolling turn that wire into a finished screw at very high speed, without cutting material away.
What is cold forming?
In cold forming (cold heading, cold forging) a piece of wire is shaped into a blank with a head and a drive by presses and dies, at room temperature. The material is not cut away but plastically deformed. This gives very high material efficiency, high productivity and dimensional repeatability even in large batches. The thread is then added by thread rolling, which also forms the material rather than cutting it.
Because the metal is formed instead of machined, the grain flow of the material follows the contour of the head and thread – one reason cold-formed fasteners are the standard choice for high-volume production.
How a screw is made at Interwolf
- Incoming material inspection – for steel and stainless steel we check the suppliers' certificates and test reports.
- Cold forming – on the presses, wire is formed into a blank with a head and drive.
- Thread rolling – metric, self-tapping or self-drilling thread, depending on the project.
- Heat treatment – carried out by certified external partners.
- Hardness testing – after heat treatment, hardness is checked in-house.
- Surface coating – zinc plating, phosphating and other protective coatings, by external subcontractors.
- Mechanical and optical sorting – optical inspection on request, with a target of up to 50 ppm.
- Packaging and dispatch – to customer specification, including small units and assembly kits.
Machines and tooling
Our production in Logatec is based on 26 cold-forming presses and 15 thread-rolling machines, covering the size range M2.5 to M8, within a machine park of more than 50 machines. Mechanical sorting and three optical sorting machines complete the line.
Tooling is decisive in cold forming: the dies determine the geometry of every screw. That is why we run our own toolshop – it makes new tools for new products, maintains them regularly and repairs any wear or damage in-house, without waiting for external suppliers. This keeps production stable and uninterrupted. See the Development page.
What it means for the customer
- Stable batches – tool wear and settings are monitored so that batches of tens of millions stay uniform. See Series production and the risk of variation.
- Tight tolerances – for certain dimensions we achieve deviations of approximately 0.02 mm, depending on the dimension and project requirements.
- Traceability – every batch is traceable from incoming material to final delivery.
Need screws made to your drawing? See Custom screws or send us your drawing – we reply within 1–2 working days.