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When a mould fails mid-run or a press tool loses its return force, the culprit is almost always an undersized or worn-out spring. Engineers, toolmakers, and serious DIY fabricators who demand consistent, repeatable performance need compression die springs rated for the actual load — not a generic substitute. These colour-coded compression die springs are designed for exactly that scenario, giving you a direct, spec-matched replacement or upgrade for stamping dies, injection moulds, and mechanical assemblies.
Each spring is manufactured from high-carbon chromium alloy steel wire, wound to a closed-end, ground-face profile for stable seating. Available in two outer diameter series — 14mm (≈0.55 in) with a 7mm (≈0.28 in) inner diameter, and 16mm (≈0.63 in) with an 8mm (≈0.31 in) inner diameter — and in free lengths ranging from 20mm (≈0.79 in) up to 300mm (≈11.81 in). Load rating is indicated by colour: Yellow (Extremely Light), Blue (Light), Red (Medium), Green (Heavy), and Brown (Extremely Heavy).
Typical use cases include injection-mould stripper plates requiring consistent ejection force, progressive stamping dies needing controlled return travel, and custom jig-and-fixture assemblies where a standard coil spring would bottom out under load. The colour-coded system also makes it straightforward to swap load ratings during prototyping without re-measuring — a time-saver on the shop floor.
| Spring Type | Compression Die Spring (Closed & Ground Ends) |
|---|---|
| Outer Diameter (OD) | 14mm (≈0.55 in) / 16mm (≈0.63 in) |
| Inner Diameter (ID) | 7mm (≈0.28 in) / 8mm (≈0.31 in) |
| Free Length Range | 20mm – 300mm (≈0.79 in – 11.81 in) |
| Load Rating / Colour | Extremely Light (Yellow) / Light (Blue) / Medium (Red) / Heavy (Green) / Extremely Heavy (Brown) |
| Material | High-Carbon Chromium Alloy Steel |
| Surface Finish | See variant options |
| Spring Rate | See variant options |
| Max. Deflection | See variant options |
| Standard Reference | ISO 10243 / JIS B 5012 |
| End Type | Closed & Ground |
| Application | Injection Moulds, Stamping Dies, Press Tools, Mechanical Assemblies |
Match the colour to the force your application requires. Yellow (Extremely Light) suits lightweight stripper plates and light-return mechanisms. Blue (Light) works for moderate ejection forces. Red (Medium) is the most common general-purpose rating for stamping and forming dies. Green (Heavy) handles high-force return applications, and Brown (Extremely Heavy) is for the most demanding tooling where maximum spring force is needed in a compact length. If you are replacing an existing spring, match the colour band on the old spring.
The outer diameter determines which spring pocket the spring fits into. The 14mm OD spring has a 7mm inner diameter (guide pin bore), while the 16mm OD spring has an 8mm inner diameter. Choose based on the pocket diameter machined into your mould or die plate. Using a spring with the wrong OD will either not seat correctly or leave excessive clearance, causing lateral movement under load.
The free length should be chosen so that the spring operates within its recommended deflection range — typically 20–30% of free length for long service life, and up to the maximum rated deflection for higher-force applications. Measure the available pocket depth and the required stroke (travel distance), then select a free length that keeps the spring within its working range. Avoid compressing die springs to solid height, as this causes rapid fatigue failure.
These springs are made from high-carbon chromium alloy steel, which offers improved corrosion resistance compared to plain carbon steel. However, they are not stainless steel. For environments with significant moisture, coolant exposure, or chemical contact, consider applying a light coating of machine oil during storage and installation. If your application requires full corrosion immunity, contact us to confirm suitability before ordering.
While these springs are dimensioned and rated to die spring standards, they can be used in any application where a compact, high-load-capacity compression spring is needed — including custom jigs, fixtures, press frames, and mechanical return mechanisms. The closed and ground ends make them suitable wherever a flat seating surface is required. Just ensure the OD, ID, free length, and load rating match your design requirements.
Replace a die spring if you observe any of the following: visible cracking or fracture of the wire coils, a measurable reduction in free length (set) of more than 3–5% compared to the original, inconsistent part ejection or return force in the tool, or if the spring has reached the manufacturer's recommended cycle count. Proactive replacement during scheduled tool maintenance is recommended for high-volume production tooling to avoid unplanned downtime.
Yes, these compression die springs are dimensioned to ISO 10243 and JIS B 5012 standards, which define the outer diameter, inner diameter, free length, load ratings, and colour coding for die springs. This means they are interchangeable with other ISO/JIS-compliant die springs of the same size and colour rating, making them a reliable drop-in replacement for tooling originally designed to these standards.
