Stock Springs · Bulk Prototyping Coils
Continuous Length Extension Springs (Cut-to-Length)
Continuous close-wound helical tension spring coils designed for engineering prototyping, plant maintenance, and custom machine builds. Supplied in standard 12-inch, 24-inch, 36-inch, or 1-meter lengths—easily cut to exact length with custom end loops formed on-site.
Advantages of Bulk Continuous Length Springs
When developing new machine prototypes or responding to emergency plant line breakdowns, waiting for custom spring tooling and coiling lead times causes expensive delays. Continuous length springs provide an instant stock solution for toolrooms and maintenance technicians.
Cut-to-Length Flexibility
Trim with heavy wire cutters to exact active coil count, yielding the exact spring rate (k) and free length needed.
Uniform Initial Tension (P₀)
Precision CNC coiling maintains consistent inter-coil contact pressure along the entire continuous length.
Premium Materials
Manufactured from high-tensile ASTM A228 music wire and corrosion-resistant ASTM A313 SUS302/304 stainless steel.
Immediate Availability
Extensive warehouse stock of standard wire and outer diameter combinations ready for same-day dispatch.
3-Step Procedure for Forming Custom End Loops in the Field
Determine required active coils N_a from your spring rate formula: N_a = (G · d⁴) / (8 · D_m³ · k). Add 2 extra coils to accommodate end loops (Total Coils N_t = N_a + 2). Cut the coil cleanly using carbide side cutters or an abrasive cutoff disc.
Insert the nose of round-nose or duckbill pliers into the end coil. Grasp the terminal coil and bend it upward 90° across the coil centerline to create an English crossover loop, or peel it outward to create a German machine hook. Ensure bend radius R ≥ 2d.
Dress the cut wire tip with a fine file to eliminate sharp burrs. Verify that the two end hooks are aligned in the same plane (or at 90° if specified) to prevent introducing unwanted torsional twist during assembly.
Standard Stock Dimensions & Specifications
| Stock Part # | Wire Dia. d (mm / in) | Outer Dia. OD (mm / in) | Standard Stock Length | Rate per Active Coil | Available Material |
|---|---|---|---|---|---|
| CLE-050-025 | 0.50 mm (0.020″) | 4.00 mm (0.157″) | 300 mm (12″) / 1000 mm | 12.5 N·mm / coil | SWP-B / SUS302 |
| CLE-080-050 | 0.80 mm (0.031″) | 6.35 mm (0.250″) | 600 mm (24″) / 1000 mm | 22.8 N·mm / coil | SWP-B / SUS302 |
| CLE-120-075 | 1.20 mm (0.047″) | 9.50 mm (0.375″) | 600 mm (24″) / 1000 mm | 48.2 N·mm / coil | SWP-B / SUS304 |
| CLE-160-100 | 1.60 mm (0.063″) | 12.70 mm (0.500″) | 900 mm (36″) / 1000 mm | 92.4 N·mm / coil | SWP-B / SUS304 |
| CLE-200-125 | 2.00 mm (0.079″) | 16.00 mm (0.630″) | 900 mm (36″) / 1000 mm | 165.0 N·mm / coil | SWP-B / SUS304 |
| CLE-300-175 | 3.00 mm (0.118″) | 25.00 mm (0.984″) | 1000 mm (39.4″) | 340.0 N·mm / coil | SWP-B / 65Mn |
Recommended Applications
R&D & Prototyping
Rapid mechanical testing and force calibration without tooling delays.
Factory Maintenance
Immediate on-site replacement for broken conveyor, chute, and gate springs.
Custom Machine Building
Special purpose machines and automated jigs requiring custom strokes.
Toolroom Stock
Essential inventory for maintenance workshops, toolmakers, and machinists.
Need Bulk Continuous Length Extension Springs?
Standard 12″, 24″, 36″, and 1000 mm bulk coils are in stock for same-day dispatch. Custom wire diameters, stainless grades, or pre-cut lengths available upon request.