Every production run passes through four tightly controlled stages, with dimensional and mechanical checks at each handoff point.
Wire pre-heating up to 1100 °C for hot coiling or direct CNC automated cold coiling depending on material grade and spring specification.
Electric furnace hardening and tempering precisely tuned to material specifications — ensuring correct hardness, yield strength and fatigue endurance.
Precision butt-end grinding followed by shot peening, chemical oxidation, zinc/cadmium plating or oil-coating per customer drawing requirements.
Full-batch in-house load testing up to 10,000 kg, mechanical property checks, free-length & squareness validation, and test certificate generation.
Each stage is governed by documented work instructions and inspection checkpoints.
All incoming wire rods are verified against mill test certificates for chemical composition, tensile strength and surface condition before entering production.
CNC coiling programs are verified against approved drawings before each production run with first-article inspection for pitch, outer diameter and free length.
Hardness is checked using Rockwell/Brinell scales after heat treatment to confirm compliance with material specification before proceeding to grinding.
Every batch is 100% dimensionally verified — free length, loaded length at test load, outer diameter, squareness — before packing and dispatch with test reports.