# @stem_antics on Instagram

- **Type:** Video
- **Original URL:** https://www.instagram.com/p/DabkDpNR6b_
- **Gondola URL:** https://gondola.cc/posts/67635472-stem-antics-instagram
- **Thumbnail:** https://img.gondola.cc/tr:w-,h-,fo-auto/postThumbnails/01af7629e1.jpg
- **Posted:** 2026-07-06T00:06:32.000+00:00
- **Account Owner:** Stem Antics (@stem_antics) — https://gondola.cc/stem_antics

## Caption

A spring is a machine that stores energy in torsion while pretending to work in compression. Push down on a helical coil and the wire itself never really compresses — it twists. Every unit of load becomes shear stress running along the wire’s length. Getting that geometry right is what spring making is really about.

It starts with the wire. High-carbon or alloy steel — music wire, oil-tempered, chrome-silicon — is patented (austenitised, then cooled through a lead or salt bath to fine pearlite) and cold-drawn through progressively smaller dies. Work hardening pushes tensile strength past 2000 MPa in the thinnest gauges.

Coiling then forms the helix:

- Cold coiling: wire is driven through feed rollers against fixed coiling points that curl it to diameter, while a pitch tool nudges each new loop sideways
- Hot coiling: heavy wire is heated to austenitising temperature, wound on a mandrel, then quenched and tempered — used where cold work would crack the section

Pitch, the axial gap between coils, is set entirely by that pitch tool. On CNC coilers its position is slaved to wire feed, so displacing it further per turn opens the helix. Vary that motion along the length and you get a progressive-rate spring that stiffens as it compresses.

Then comes the finishing that decides fatigue life:

- Stress-relief tempering removes residual coiling stress
- Shot peening drives a compressive skin that resists crack initiation
- Setting, or scragging, compresses to solid to lock in beneficial residual stress

Rate follows k = Gd⁴/8D³n. Pitch never appears in it — yet it fixes free length, active coils and the helix angle everything else leans on.

The precision isn’t in the metal. It’s in the twist.

#stemantics #engineering #manufacturing #materialscience #mechanicalengineering

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## Tags

engineering, materialscience, manufacturing, mechanicalengineering, stemantics

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