Heat-Resistant Coil Springs
Round wire and flat wire coil springs for injection mold ejection and stripper plate return. Available in six load grades (SWF through SWY) with deflection ratings from 30% to 65%, all rated for continuous operation at 200°C. SiCr alloy wire (SWOSC-V) and hardened alloy steel options.
Heat-Resistant Coil Springs — 10+ Products
Heat Resistant Round Wire Spring - 60% Deflection (WFH Se...
Heat Resistant Round Wire Spring - 60% Deflection (WFH Series) delivers stable performance at 200°C. Built for reliab...
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WLH Series Heat Resistant Round Wire Spring - 50% Deflection
WLH Series Heat Resistant Round Wire Spring - 50% Deflection designed for continuous service up to 200°C. Request a q...
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WHH Series 35% Deflection Heat Resistant Coil Spring
WHH Series 35% Deflection heat resistant round wire coil spring rated for up to 200°C. Built for stable load response...
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Heat Resistant Round Wire Spring 40% Deflection (WMH Series)
Heat Resistant Round Wire Spring 40% Deflection (WMH Series) built for durability at 200°C. Coil spring for reliable ...
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Super-High Deflection Coil Spring - 60% Deflection
Super-high deflection coil spring for 60% deflection loads, SWU Series. Heat resistant to 200°C, flat wire type for s...
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Ultra-High Deflection Coil Springs - 65% Deflection SWY S...
Ultra-High Deflection Coil Springs - 65% Deflection SWY Series for demanding spring applications with up to <b>200°C<...
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High Deflection Coil Springs (50% Deflection) SWR Series
High Deflection Coil Springs (50% Deflection) SWR Series with 200°C heat resistance and flat wire design. Ideal for l...
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SWS Series Medium Deflection Coil Springs (40% Deflection...
SWS Series medium deflection coil springs (40% deflection) with flat wire for stable force in demanding setups. Heat ...
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Low Deflection Coil Spring - 30% Deflection, SWN Series
Low Deflection Coil Spring 30% Deflection (SWN Series) for stable force in machinery. Heat resistant up to 200°C with...
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PCS Coil Springs - Heavy Pressure - Inch
PCS Coil Springs - Heavy Pressure - Inch made of hardened alloy steel with gold/silver color coding and E-coat corros...
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Coil Springs - Medium Pressure - Inch
Coil Springs - Medium Pressure - Inch made from hardened alloy steel with blue/silver color coding. E-coat corrosion ...
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Coil Springs - Med-Heavy Pressure - Inch
Coil Springs - Med-Heavy Pressure - Inch made of hardened alloy steel with E-coat corrosion protection for long servi...
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Coil Springs - Extra-Heavy Pressure - Inch
Coil Springs - Extra-Heavy Pressure - Inch made from hardened alloy steel with green/silver color coding and E-coat c...
View DetailsRound Wire vs Flat Wire Coil Springs
Coil springs for injection molds come in two fundamental wire cross-sections, each with distinct advantages:
| Dimension | Round Wire (SW-series) | Flat Wire (SWU/SWR/SWS/SWN/SWY) |
|---|---|---|
| Wire Cross-Section | Circular (standard DIN 17223 / JIS G3561) | Rectangular (cold-rolled from round stock) |
| Force per Pocket Depth | Baseline (1.0x) | 1.2-1.3x (rectangular coils nest tighter) |
| Lateral Stability | Good — may buckle if L/D ratio > 4:1 | Excellent — rectangular section resists buckling |
| Cost | Lower (standard wire stock) | 15-25% premium (cold-rolling process) |
| Availability | Standard catalog, same-day shipping | Standard catalog, 1-3 day shipping |
| Best For | Standard ejector/stripper return with adequate pocket depth | Space-constrained applications, high-force in shallow pockets |
How to Select the Right Deflection Grade
Deflection percentage is the maximum safe compression ratio of a spring. A 40% deflection spring with a 50mm free length can be compressed to 30mm (50 × 0.40 = 20mm compression) without permanent deformation.
- 30% (SWN/SWH): Highest load capacity per coil. Use when you have generous pocket depth but need maximum force. Longest fatigue life.
- 40% (SWM/SWS): Best balance of force and stroke. Standard choice for 80% of mold applications.
- 50% (SWL/SWR): Greater stroke in a shorter free length. Use when pocket depth is limited but moderate force is acceptable.
- 60-65% (SWF/SWU/SWY): Maximum stroke from minimum pocket depth. Lower cycle life — use only when space constraints demand it.
Key formula: Spring force at working height = Spring rate (k) × Compression distance. Always verify that the force at maximum deflection does not exceed the spring's rated load.
Application Scenarios
Ejector Plate Return
Pain point: Ejector plate does not return fully or consistently, causing short shots or part damage on the next cycle.
Why it fits: SWM (Red/Medium) round wire springs at 40% deflection provide consistent return force over millions of cycles. The 200°C heat resistance prevents force degradation in heated molds.
Recommended: WMH Series (SWM) Round Wire, 40% Deflection
Stripper Plate Separation
Pain point: Stripper plate requires high initial force to break part adhesion, but limited pocket depth restricts spring size.
Why it fits: SWU flat wire springs deliver 20-30% more force per unit depth than round wire. The 60% deflection rating allows maximum stroke from shallow pockets.
Recommended: SWU Series Flat Wire, 60% Deflection
High-Temperature Resin Molds
Pain point: Springs in PPS/PEEK molds (180-200°C base temperature) lose load capacity rapidly, requiring frequent replacement.
Why it fits: SWOSC-V SiCr alloy wire maintains 95%+ load capacity at 200°C over 1M+ cycles. No load loss compared to standard carbon steel springs that fail at 120°C.
Recommended: WHH Series (SWH) Heavy Load, 200°C Rated
Specification Quick Reference
Standard coil spring dimensions available across all load grades:
| Outer Diameter (mm) | Available Free Lengths (mm) | Wire Types | Load Grades |
|---|---|---|---|
| 5 - 8 | 10, 15, 20, 25, 30 | Round | SWF, SWL, SWM, SWH |
| 10 - 16 | 15, 20, 25, 30, 40, 50 | Round, Flat | All (SWF-SWY) |
| 18 - 25 | 20, 25, 30, 40, 50, 60, 80 | Round, Flat | All (SWF-SWY) |
| 27 - 35 | 25, 30, 40, 50, 60, 80, 100 | Round, Flat | SWM, SWH, SWU, SWY |
| 40 - 50 | 30, 40, 50, 60, 80, 100, 125 | Flat | SWU, SWY |
Materials: SiCr alloy wire (SWOSC-V, JIS G3561) for round wire. Cold-rolled alloy steel for flat wire. Hardened alloy steel with E-coat for PCS inch series. Custom lengths and OD available on request (MOQ: 50 pcs).
Engineering Resources
Frequently Asked Questions
What is the difference between SWM and SWH load grades?+
How many cycles can I expect from a heat-resistant coil spring?+
Can I use these springs in press die applications?+
Do you offer custom spring rates?+
Need a Custom Quote?
Send your specifications and receive a quote. MOQ: 1 piece. Custom dimensions available.