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When your stamping die, injection mould, or precision jig demands consistent spring-back force without premature fatigue, choosing the wrong spring means costly downtime and scrapped parts. Engineers, toolmakers, and serious DIYers who work with mould bases, progressive dies, and fixture plates need a die spring that holds its rated load cycle after cycle. These die springs compression mould springs are engineered for exactly that — delivering repeatable performance across light, medium, and heavy load ratings in a single product family.
Each spring is manufactured from high-grade chromium-silicon alloy steel wire, wound to a rectangular cross-section for maximum energy storage per unit length. Available in three outer diameter series — 10mm (ID 5mm), 12mm (ID 6mm), and 14mm (ID 7mm) — with free lengths ranging from 15mm to 300mm (approximately 0.59 in to 11.81 in). Colour coding follows the ISO 10243 standard: Yellow (TF) = light load, Blue (TL) = light-medium load, Red (TM) = medium load, Green (TH) = heavy load, Brown (TB) = extra-heavy load.
Typical use cases include injection mould stripper plate actuation, metal stamping die cushioning, spring-loaded fixture clamping, and precision machine tool preloading — all long-tail applications where standard round-wire compression springs fail to deliver the deflection-to-length ratio required by tight mould pockets.
| Spring Type | Rectangular wire die spring (compression) |
|---|---|
| Outer Diameter (OD) | 10mm / 12mm / 14mm |
| Inner Diameter (ID) | 5mm (OD 10) / 6mm (OD 12) / 7mm (OD 14) |
| Free Length Range | 15mm – 300mm (0.59 in – 11.81 in) |
| Wire Cross-Section | Rectangular (flat wound) |
| Material | Chromium-silicon alloy steel |
| Load Rating / Colour Code | Yellow = Light (TF) · Blue = Light-Medium (TL) · Red = Medium (TM) · Green = Heavy (TH) · Brown = Extra-Heavy (TB) |
| Standard Reference | ISO 10243 / JIS B 5012 |
| Surface Finish | See variant options |
| Recommended Max Deflection | See variant options |
| End Type | Closed & ground (typical for die springs) |
| Quantity per Order | 1 piece (Pcs) |
Match the colour to your required spring rate. Yellow (TF) suits light-load stripper plates and ejector systems. Blue (TL) is a light-medium option for moderate preload fixtures. Red (TM) covers standard medium-load progressive die applications. Green (TH) handles heavy-load blanking and forming dies. Brown (TB) is for extra-heavy-load applications where maximum force per unit length is needed. If you know your required load (N) and deflection (mm), calculate the spring rate (N/mm) and select the colour whose rated stiffness matches.
The spring OD must fit inside your pocket bore with a small clearance (typically 0.5–1mm per side). The spring ID must clear your guide pin with a small clearance (typically 0.3–0.5mm per side). For a 10mm OD spring, the pocket bore should be at least 10.5–11mm and the guide pin no larger than 4.5mm. For 12mm OD, pocket bore ≥ 12.5–13mm, guide pin ≤ 5.5mm. For 14mm OD, pocket bore ≥ 14.5–15mm, guide pin ≤ 6.5mm. Always verify against your specific tooling drawings.
ISO 10243 die springs are typically rated for a maximum deflection of 20–30% of free length depending on load grade — lighter grades allow slightly more deflection, heavier grades less. Operating beyond the rated deflection causes permanent set and premature fatigue failure. For exact figures per size and colour, refer to the ISO 10243 load-deflection tables or contact us to confirm for your specific variant.
Chromium-silicon alloy steel provides better oxidation resistance than plain carbon steel, but these springs are not stainless steel. In environments with continuous coolant exposure or high humidity, consider applying a light oil coating during storage and installation. For aggressive corrosive environments, contact us to confirm suitability or discuss alternative surface treatment options.
Chromium-silicon alloy steel retains its mechanical properties at moderately elevated temperatures (typically up to around 120–150°C / 248–302°F) better than standard carbon steel springs. For mould applications where the spring pocket regularly exceeds this range, verify the operating temperature against the spring material specification or contact us to confirm suitability for your specific mould temperature.
The OD series is primarily determined by your existing die pocket bore size and the load you need to achieve. Larger OD springs (14mm) can store more energy and carry higher loads at the same free length compared to smaller OD springs (10mm). If your pocket size allows multiple options, choose the larger OD for higher load capacity or the smaller OD to fit tighter pocket arrangements. Always cross-reference the rated load at your working deflection for the selected colour and OD combination.
These springs are designed to the ISO 10243 / JIS B 5012 dimensional and colour-coding conventions, which are the internationally recognised standards for rectangular-wire die springs. This means they are dimensionally interchangeable with other ISO 10243-compliant springs of the same OD, ID, and free length. If your tooling was designed to these standards, these springs will fit the same pockets and guide pins.
