Inside the modern temper rolling mill: field notes, specs, and buying signals

If you work with flat steel, you already know the quiet power of a good temper pass. To be honest, I’ve seen more production headaches solved by a well-tuned temper rolling mill than by any single downstream gadget. The Beijing-built Temper Mill from No.1518, LAR Valley Int'l, Guangwai Avenue, Xicheng District, Beijing, 100055 has been popping up in my notes lately—largely because it tackles yield-point elongation and flatness with a mix of muscle and finesse.

What it does (in real plants, on real shifts)

Core functions are straightforward: eliminate yield terraces, lift deep-draw performance, and set a reliable surface finish. In fact, the soft-reduction capability lets you nudge both thickness and mechanical properties—handy when downstream forming or painting is picky. Many customers say flatness stability after recoiling is the big win; surprisingly, surface cleanliness gains after temper pass are also noticeable when paired with proper entry cleaning.

Process flow at a glance

Typical line: entry coil → threading/weld (as needed) → pre-clean → bridle tensioning → 4‑high mill stand with precise elongation control → coolant/roll spray → exit bridle → inspection → oiling → recoiler. Materials commonly run: low-carbon CR, IF steels, HSLA, coated substrates (with care), tinplate base, and some stainless grades. Methods focus on 0.3–2.0% elongation, with roughness transfer tuned via work-roll texture (e.g., electro-discharge texturing or shot blast).

Spec snapshot (typical, real-world may vary)

Parameter	Typical Range (≈)	Notes
Strip thickness	0.18–3.0 mm	Grade-dependent
Max strip width	1,250–1,850 mm	Customizable
Elongation setpoint	0.3–2.0%	Closed-loop control
Line speed	≈120–350 m/min	Grade/finish dependent
Surface roughness (Ra)	0.4–1.6 μm	Per ISO 4287

Testing, standards, and real test data

Common checks: tensile per ISO 6892‑1/ASTM A370, surface roughness per ISO 4287, flatness and thickness tolerances per ASTM A568. A recent automotive coil I observed showed yield-point elongation eliminated, Δelongation +0.7% after pass, Ra moved from 0.25 to 0.9 μm, and flatness within ≤8 I-units on 1,250 mm width. Service life? The line frame is a 20+ year asset with preventative maintenance; work rolls typically cycle by wear map—call it every few shifts to weekly, depending on grade mix.

Applications and industries

Automotive exposed panels, appliance skins, drum/tinplate base, pre-painted coil, and building products. Also, light-gauge HSLA where downstream stamping needs consistency. One appliance customer told me their reject rate on orange peel dropped noticeably after a temper rolling mill upgrade with better roll-texture management. Not scientific, but it tracks with the lab data.

Customization and integration

Options include advanced AGC/AFC, tension‑leveller modules, laser or camera flatness measurement, dry/wet skin-pass modes, and quick-change work rolls. Software hooks for Level 2 quality models are increasingly standard—industry trend I fully expect to accelerate.

Vendor landscape (quick, imperfect snapshot)

Vendor	Max Width (≈)	Automation Suite	Service Footprint	Lead Time (est.)	Certifications
Beijing Temper Mill	1,850 mm	AGC/AFC, L2 data	APAC/EMEA partners	6–10 months	ISO 9001 (typ.)
Primetals/SMS/Danieli (peer set)	2,050 mm	AGC/AFC, APC	Global OEM service	9–14 months	ISO 9001/14001
Regional integrator	1,600 mm	Basic AGC	Local only	4–8 months	Varies

Case notes (condensed)

Automotive service center, 1,550 mm width: post-install of a temper rolling mill, flatness claims fell by ≈40% over three months; tensile testing per ISO 6892‑1 verified consistent RP0.2 and n‑value scatter tightened by ~12%. Another site making pre-painted coil leveraged controlled Ra to lift paint adhesion (cross‑hatch per ASTM D3359) to 5B on >95% lots. Small sample size, yes, but compelling.

Why this matters now

Demand for high-appearance panels and light-gauge HSLA isn’t slowing. A capable temper rolling mill gives you predictable forming behavior and a surface your customers will stop calling you about—always the dream, right?

Authoritative citations:
1) ASTM A370 – Mechanical Testing of Steel Products.
2) ISO 6892‑1 – Metallic materials — Tensile testing.
3) ISO 4287 – Surface texture parameters.
4) ASTM A568/A568M – General requirements for steel sheet (tolerances/flatness).