Inside Our Manufacturing Process: From Wire to Finished Spring

Most people assume spring manufacturing is simple: take some wire, coil it, done. It isn't quite that simple, and understanding the actual steps is useful if you're evaluating whether a manufacturer can hold your tolerances consistently, order after order.

Selecting the Wire

It starts with the wire itself. We stock spring steel in SM/DM and SH/DH grades, along with SS304 and SS316 stainless, music wire and oil-tempered wire — the right starting material depends entirely on the load, cycle life and environment your spring needs to survive. Get this step wrong and no amount of precision downstream fixes it.

Coiling to Spec

From there, coiling. Wire is fed through a coiling machine set to your exact wire diameter, coil diameter, pitch and number of active coils — the core parameters we cover in how to specify a custom spring. Small variations here directly change spring rate, so this is where dimensional discipline matters most.

Heat Treatment

Next comes heat treatment. Coiled wire is under internal stress from the winding process — without proper stress-relieving, springs would lose their set quickly or fail early in service. We heat treat to relieve that stress while preserving the mechanical properties the material was chosen for in the first place.

End Forming

End forming is where compression, extension and torsion springs actually diverge. Compression springs get their ends squared and ground for stable seating. Extension springs get hooks or loops formed, depending on how the spring attaches in your assembly. Torsion springs get their legs bent to the angle and length your application requires. This stage is largely manual skill, not just machine settings — it's where experienced operators earn their keep.

Finishing and Testing

Then surface finishing: zinc plating, powder coating or passivation for stainless parts, depending on the corrosion resistance your application demands.

Finally, testing. Every batch is checked for free length, load at specified deflection, and dimensional conformance before it ships — this is also where our ISO 9001:2015 quality system does its actual work, not just as a certificate on the wall.

What This Means for You as a Buyer

What does this mean for you as a buyer? Mainly this: a spring that looks right and a spring that performs consistently in your assembly for its full service life are not automatically the same thing. The difference comes from control at every one of these steps.

If you're specifying a custom spring for the first time, our spring design guide walks through the technical side in more depth. And if you already know your spring type, our extension springs page shows the actual configurations we manufacture day to day.