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When a worn or under-rated spring causes a stamping die to misfire or an injection mould to stick, the entire production run stops. Engineers and toolmakers who rely on consistent spring force need a compression die mould spring that holds its rated load cycle after cycle without fatigue. The TH Green Heavy-Load series is engineered for exactly that demand, making it the go-to choice for mould shops, press-tool builders, and maintenance teams running high-tonnage equipment.
These compression die mould springs are manufactured from rectangular-section alloy spring steel wire, wound to a close-coiled cylindrical form and finished in a distinctive green coating for easy load-class identification. Outer diameters span Φ6 mm (0.24 in) through Φ60 mm (2.36 in), with inner diameters sized at approximately half the OD to suit standard guide pins. Free lengths range from 15 mm (0.59 in) to 300 mm (11.81 in), covering the full spectrum of die-set and mould-base pocket depths.
Typical applications include progressive stamping dies requiring consistent blank-holder force, injection-mould ejector-pin return springs for high-cycle plastic tooling, and hydraulic press stripper-plate springs where controlled deflection under heavy load is critical to part quality.
Colour-coded green per ISO 10243 / JIS B 5012 heavy-load class, delivering higher spring force per unit deflection than light or medium grades — ideal for high-tonnage stamping and moulding operations.
OD from Φ6 mm to Φ60 mm and free lengths from 15 mm to 300 mm give toolmakers a single source for virtually every die-set pocket or mould-base spring seat encountered in production tooling.
Flat-wire winding maximises the active coil cross-section within a given OD/ID envelope, producing a higher solid-height ratio and more usable deflection compared with round-wire alternatives.
Chrome-silicon or chrome-vanadium alloy steel (grade varies by size) provides fatigue resistance across millions of cycles, maintaining consistent spring rate even under repeated high-deflection loading.
Flat-ground end faces ensure square seating on guide pins and spring pockets, preventing lateral shift under load and extending both spring and tooling service life.
Dimensioned to match standard ISO / JIS die-spring catalogues, allowing direct substitution for worn springs without re-machining spring pockets or guide pins.
| Type | Compression Die Mould Spring |
|---|---|
| Load Class | TH — Heavy Load (Green) |
| Standard | ISO 10243 / JIS B 5012 |
| Outer Diameter (OD) | Φ6 mm – Φ60 mm (0.24 in – 2.36 in) |
| Inner Diameter (ID) | Approx. 50% of OD (see variant options) |
| Free Length | 15 mm – 300 mm (0.59 in – 11.81 in) |
| Wire Section | Rectangular (flat-wound) |
| Material | Alloy spring steel (chrome-silicon / chrome-vanadium) |
| Surface Finish | Green coating (load-class identification) |
| End Type | Flat ground |
| Deflection Rate | See variant options |
| Operating Temperature | Up to approximately 80 °C (176 °F) continuous |
| Colour | TH Green (Heavy Load) |
Match the outer diameter (OD) to your spring pocket bore and the inner diameter (ID) to your guide-pin diameter, leaving a clearance of typically 0.5–1 mm on each side. For example, a Φ12 mm guide pin pairs well with the 14 mm × 7 mm variant. Always verify against your die drawing before ordering.
Under ISO 10243 and JIS B 5012, die springs are colour-coded by load class: green indicates the Heavy Load (TH) class, which delivers the highest spring force per unit deflection in the standard range. This makes TH Green springs suitable for high-tonnage stamping, thick-material blanking, and heavy ejector-return duties.
When operated within the recommended deflection range (typically 20–30% of free length for heavy-load springs), alloy die mould springs of this class are designed for approximately 500,000 to 1,000,000 cycles. Exceeding the rated deflection significantly reduces fatigue life. Inspect springs regularly for set (permanent shortening) and replace when free length drops more than 3% from nominal.
The green surface coating provides a degree of corrosion protection for typical workshop and toolroom environments. For applications with continuous coolant exposure or high humidity, consider applying a light oil film during storage and installation. The alloy steel core is not stainless; prolonged immersion in water or aggressive coolants is not recommended.
Yes. TH Green compression die mould springs are widely used as ejector-pin return springs in injection moulds. Select a free length that allows full ejector stroke plus a pre-load of 10–15% of free length to keep the ejector plate seated during the injection phase. Confirm the OD fits your mould-base spring pocket and the ID clears the ejector guide sleeve.
Choose TH Green (Heavy Load) when you need maximum force in a compact spring pocket — for example, high-tonnage blanking dies, thick-plate forming tools, or applications where space constraints prevent using a longer, lighter spring. If your application requires a softer, more progressive force curve or the tooling cannot withstand high spring-back forces, a medium (blue) or light (yellow) class may be more appropriate.
A common rule of thumb is to select a free length 1.5–2× the required working stroke, so the spring operates at 30–50% deflection under load. For example, if your die opens 30 mm, a free length of 50–60 mm keeps the spring within a safe deflection range. Always check the manufacturer's deflection chart for the specific OD/ID combination to confirm the force at your working deflection.
