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When your mold tooling demands consistent, repeatable spring force without premature fatigue, a poorly matched spring becomes the weakest link in your production cycle. These OD 8mm ID 4mm compression die springs are engineered for hobbyists, toolmakers, and small-batch manufacturers who need dependable elastic return force in confined mold cavities and precision fixtures.
Each spring features an outer diameter of 8 mm (0.315 in) and an inner diameter of 4 mm (0.157 in), with available free lengths ranging from 10 mm to 300 mm (0.39 in to 11.81 in). Three material grades are offered — Alloy steel, SWOSC-V (silicon-chrome oil-tempered wire), and 65Mn spring steel — to match your load, corrosion, and fatigue requirements. Five color-coded load ratings (TF-Yellow / TL-Blue / TM-Red / TH-Green / TB-Brown) follow the standard die spring classification system for quick visual identification.
Typical use cases include injection mold stripper plates requiring light-load TF-Yellow compression die springs, stamping die assemblies needing medium-load TM-Red mold springs, and heavy-duty TH-Green or TB-Brown die springs for high-cycle press tooling and industrial fixture clamping applications.
Outer diameter 8 mm / inner diameter 4 mm maintains consistent fit in standard die pockets and guide pin assemblies across mold and stamping tooling.
TF-Yellow (light), TL-Blue (light-medium), TM-Red (medium), TH-Green (heavy), and TB-Brown (extra-heavy) allow instant visual load identification on the shop floor.
Choose Alloy steel for general tooling, SWOSC-V silicon-chrome wire for extended fatigue life, or 65Mn spring steel for cost-effective medium-duty applications.
Free lengths from 10 mm (0.39 in) to 300 mm (11.81 in) cover short-stroke ejector pins through long-travel stripper plate assemblies in a single product family.
SWOSC-V grade springs are oil-tempered after coiling for superior fatigue resistance, supporting extended production runs with reduced spring replacement frequency.
Springs are finished to resist oxidation in typical workshop and toolroom environments, maintaining dimensional stability and spring rate over the service life.
| Outer Diameter (OD) | 8 mm (0.315 in) |
|---|---|
| Inner Diameter (ID) | 4 mm (0.157 in) |
| Free Length Range | 10 mm – 300 mm (0.39 in – 11.81 in) |
| Load Rating Options | TF-Yellow / TL-Blue / TM-Red / TH-Green / TB-Brown |
| Material Options | Alloy steel / SWOSC-V / 65Mn |
| Wire Type (SWOSC-V) | Silicon-chrome oil-tempered round wire |
| End Type | Closed and ground ends (typical die spring standard) |
| Coil Direction | Right-hand wound |
| Spring Rate | See variant options |
| Max Deflection | See variant options |
| Surface Finish | See variant options |
| Operating Temperature | See variant options |
Select the load rating based on the force required at your working deflection. TF-Yellow is the lightest load, suitable for light ejector pin return applications. TL-Blue and TM-Red cover light-medium and medium loads for general stripper plates. TH-Green and TB-Brown are for heavy and extra-heavy duty press tooling. If you are unsure, calculate the required spring force at your target deflection and match it to the spring rate of the chosen color grade.
Alloy steel is a general-purpose spring material suitable for standard tooling environments. SWOSC-V (silicon-chrome oil-tempered wire) offers superior fatigue life and is recommended for high-cycle applications where the spring is deflected millions of times. 65Mn is a manganese spring steel that provides a cost-effective option for medium-duty, lower-cycle applications. Choose SWOSC-V when longevity and fatigue resistance are the priority.
Yes. The OD 8mm / ID 4mm dimensions and color-coded load classification system align with the ISO 10243 and JIS B 5012 die spring standards, making these springs interchangeable with other compliant die springs of the same size and load rating in your tooling.
Measure the available pocket depth in your mold or die and determine the required working stroke. The free length should be long enough so that at maximum deflection the spring does not exceed its rated maximum compression (typically 30–45% of free length for die springs). Add the working stroke to the compressed length to determine the minimum free length needed. Available lengths range from 10 mm to 300 mm in this product family.
These springs are designed for toolroom and workshop use. While the surface finish provides basic oxidation resistance, prolonged exposure to moisture, chemicals, or outdoor conditions may accelerate corrosion. For humid or corrosive environments, consider applying a light machine oil coating or contact us to confirm the most suitable material grade for your specific conditions.
The 4 mm inner diameter accommodates guide pins up to approximately 3.5–3.8 mm in diameter, allowing sufficient clearance for smooth spring travel without binding. For precise fit requirements, verify the pin diameter against the spring ID with a small clearance allowance (typically 0.2–0.5 mm) to prevent coil binding on the pin during compression.
Each listing is sold per individual spring (quantity of 1) unless a multi-pack option is selected in the variant options above. Please select your required quantity and variant combination before adding to cart.
