Piano Wire Round Wire Coil Springs - 40% Deflection, WL Series

This round-wire coil spring variant is used inside precision injection mold tooling where a consistent force over stroke is required—especially in mechanisms that must maintain repeatability across cycles.

• Automotive connector and terminal molds: suited for ejector or slide return support, where maintaining a stable force curve through 40% allowable deflection helps prevent sticking and improves cycle-to-cycle uniformity.
• Medical device housing molds: used in load-holding or micro-actuation features that require predictable spring response to keep components clamped during post-mold handling.
• Consumer electronics insert molds: ideal for motion or clamping systems that benefit from piano-wire elasticity and controllable spring constant selection for your required opening/closing timing.

The WL-series geometry and piano-wire construction support uniform elastic behavior, enabling engineers to tune spring rate via the available spring constant (0.5, 1.0, 2.9 N/mm) and match maximum load needs.

This product is specified as piano wire (music-wire style), selected for its high elastic uniformity and predictable spring-back in compression or extension strokes.

• Material behavior: piano wire typically provides high wear resistance at the spring surface and excellent fatigue performance when deflection stays within the designed allowable range (here, 40% deflection).
• Heat treatment (typical for piano wire): wire is commonly supplied in a hardened condition and finished for spring use; for maximum life, it is expected to be manufactured to spring-grade mechanical properties rather than annealed steel.
• Trade-offs: higher hardness improves fatigue strength and wear resistance, but can reduce toughness margin—reinforcing the importance of selecting the correct length and working load.

If you compare alternatives, pre-hardened spring steels may be easier to form but often require more careful rate validation; the piano-wire approach emphasizes stable elasticity for controlled force curves.

Select spring dimensions first, then confirm the force/load envelope for your mechanism so operation stays within the designed allowable deflection.

• Outer diameter (OD), D: choose from 2–27 mm to match surrounding guide clearances in your mold cavity/core layout and to avoid interference with neighboring components.
• Free length, L: use the available 5–100 mm range, then calculate your expected compression/extension stroke so the working deflection does not exceed the 40% allowable deflection requirement.
• Spring constant (k): pick 0.5, 1.0, or 2.9 N/mm to achieve the required force response over your stroke.
• Maximum load: verify the spring’s specified 0.98–117.7 N maximum load covers your highest expected operating load with a safety margin.

Tolerances are not provided in the supplied data; therefore, validate fit by checking your assembly clearance and allowing for normal spring manufacturing variations.