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Engineers and toolmakers working with stamping dies, injection moulds, and progressive tooling know the frustration of springs that fatigue prematurely or deliver inconsistent force. These compression die mould springs are engineered for repetitive-cycle industrial environments where dimensional accuracy and load consistency are non-negotiable.
Each spring features a rectangular cross-section wire wound to a closed-end coil configuration, available in two outer diameter sizes — 18mm (inner diameter 9mm) and 20mm (inner diameter 10mm) — with free lengths ranging from 20mm to 300mm (approximately 0.79 in to 11.81 in). Load ratings span light duty (Yellow/TF), medium duty (Blue/TL & Red/TM), and heavy duty (Green/TH & Brown/TB) classifications, colour-coded for instant identification on the shop floor.
Typical use cases include compression die mould spring replacement in stamping presses, stripper plate return mechanisms in progressive dies, and spring-loaded ejector pin assemblies in plastic injection moulds — all scenarios where a consistent, repeatable spring force is critical to part quality and tool longevity.
| Outer Diameter (OD) | 18mm / 20mm |
|---|---|
| Inner Diameter (ID) | 9mm (for OD 18mm) / 10mm (for OD 20mm) |
| Free Length Range | 20mm – 300mm (0.79 in – 11.81 in) |
| Wire Cross-Section | Rectangular |
| End Type | Closed & Ground |
| Load Class / Colour Code | Light Duty – Yellow (TF); Medium Duty – Blue (TL), Red (TM); Heavy Duty – Green (TH), Brown (TB) |
| Material | Alloy spring steel |
| Surface Finish | See variant options |
| Coil Direction | See variant options |
| Standard Reference | ISO 10243 (die spring classification) |
| Weight | See variant options |
Measure the available spring pocket depth in your tooling plate and determine the required working stroke. A common rule of thumb is to select a free length that allows no more than 30–40% deflection at maximum working load to preserve fatigue life. For example, if your stroke is 20mm, a free length of 50–65mm is typically appropriate. Always cross-reference with your tooling designer's specification.
The colour code indicates the spring's load rating per unit of deflection (spring rate). Yellow (TF) is the lightest load class, suited to applications requiring low force such as light stripper plates. Blue (TL) and Red (TM) are medium duty, covering the majority of general stamping and moulding applications. Green (TH) and Brown (TB) are heavy duty, designed for high-force requirements such as heavy blanking or deep-draw tooling.
Yes. These springs are designed to ISO 10243 die spring dimensional and load standards, which are widely adopted in tooling manufactured to DIN, JIS, and equivalent international specifications. Always verify the OD, ID, and free length against your specific die set drawing before installation.
Fatigue life depends heavily on the deflection ratio used in service. Operating within the recommended deflection range (typically up to 30% of free length for heavy duty, up to 40% for light duty) can yield cycle lives in the range of 500,000 to over 1,000,000 cycles. Exceeding the recommended deflection significantly reduces service life. Contact us to confirm specifications for your specific application.
These springs are manufactured from alloy spring steel and are suitable for standard workshop and production tooling environments. For applications involving exposure to cutting fluids, coolants, or elevated temperatures above typically 80°C, additional surface treatment or a different material grade may be advisable. Contact us to confirm suitability for your specific conditions.
The selection is determined by the spring pocket bore diameter in your tooling plate. OD 18mm springs fit pockets bored to 18mm (with a 9mm guide pin), while OD 20mm springs fit 20mm pockets (with a 10mm guide pin). Refer to your die or mould drawing for the specified spring pocket and guide pin dimensions.
These letter codes correspond to ISO 10243 load class designations: TF = Light Duty (Yellow), TL = Medium-Light Duty (Blue), TM = Medium-Heavy Duty (Red), TH = Heavy Duty (Green), TB = Extra Heavy Duty (Brown). Selecting the correct class ensures the spring delivers the intended force at your required deflection.
