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Engineers and toolmakers working with injection molds, stamping dies, and precision fixtures know the frustration of springs that fatigue prematurely or fail to deliver consistent force. These heavy-duty compression mold springs are engineered for exactly those environments, offering a wide selection of outer diameters and lengths to match virtually any mold or die cavity requirement.
Each spring is a round-wire coil compression spring manufactured from high-carbon or alloy steel wire, with outer diameters (OD) ranging from 10.5 mm (approx. 0.41 in) to 50 mm (approx. 1.97 in) and inner diameters (ID) sized to match standard guide pins. Lengths span from 15 mm (approx. 0.59 in) up to 400 mm (approx. 15.75 in), with load ratings from 8 KG to 135 KG depending on the size selected.
Typical use cases include injection mold ejector systems requiring consistent return force, progressive stamping die stripper plates needing reliable spring-back, and industrial fixture clamping mechanisms where repeatable deflection is critical. These springs are also well-suited for heavy-duty compression spring replacement in automation jigs and robotic end-of-arm tooling.
| Spring Type | Round-wire coil compression spring |
|---|---|
| Outer Diameter (OD) Range | 10.5 mm – 50 mm (approx. 0.41 in – 1.97 in) |
| Inner Diameter (ID) Range | 6 mm – 36 mm (see variant options) |
| Free Length Range | 15 mm – 400 mm (approx. 0.59 in – 15.75 in) |
| Load / Bearing Weight | 8 KG – 135 KG (varies by OD × ID × length) |
| Wire Material | See variant options |
| Surface Finish | See variant options |
| End Type | Closed and ground ends (typical for mold springs) |
| Application | Injection molds, stamping dies, fixture clamping, automation tooling |
| Sold As | 1 piece per unit (qty packs available — see variant options) |
Match the inner diameter (ID) of the spring to the outer diameter of your guide pin, leaving a small clearance (typically 0.5–1 mm) for smooth travel. Then select an outer diameter that fits within your spring pocket without binding. For example, if your guide pin is 6 mm OD, the 10.5 × 6 mm spring is a natural fit.
The bearing weight indicates the approximate maximum static load the spring can support at a defined deflection. When selecting a spring, ensure the required ejection or stripping force falls within this rating. For cyclic applications, it is advisable to operate at 70–80% of the rated load to extend service life.
Standard carbon steel mold springs are suitable for typical injection mold operating temperatures (up to approximately 80–120°C). For higher-temperature applications, please contact us to confirm material suitability before ordering.
Standard mold springs have a surface treatment (such as paint or phosphate coating) that provides moderate corrosion protection for indoor tooling environments. They are not intended for prolonged exposure to water, coolant, or corrosive chemicals. If corrosion resistance is a priority, contact us to confirm available finish options.
The free length should be chosen so that the spring is slightly pre-compressed when installed (pre-load), ensuring it maintains contact and delivers force throughout the full stroke. A common rule of thumb is to select a free length that is 20–30% longer than the installed (compressed) length. Verify against your mold's stroke and pocket depth.
Yes. These springs are sized to match standard mold spring dimensions used across the industry. Select the OD × ID combination and free length that matches your existing spring's dimensions, then verify the load rating aligns with your application's force requirements.
Larger OD × ID combinations (e.g., 50 × 36 mm) have a thicker wire cross-section and higher load ratings (up to 135 KG), making them suitable for heavy stripper plates and large ejector systems. Smaller combinations (e.g., 10.5 × 6 mm, rated 8 KG) are ideal for small ejector pins and light-duty return mechanisms. Choose based on your required force and available pocket space.
