Copper Buckle Shaft Torsion Springs Collection 02 is a dedicated series of custom torsion springs engineered for shaft-mounted rotary return mechanisms, particularly in buckle assemblies, latch system
Copper Buckle Shaft Torsion Springs Collection 02 is a dedicated series of custom torsion springs engineered for shaft-mounted rotary return mechanisms, particularly in buckle assemblies, latch systems, and compact actuator housings. We manufacture these coils with a positional tolerance of ±0.01 mm on the leg bend, a total runout of 0.02 mm TIR on the inner diameter, and a consistent hardness of 44–48 HRC, with a standard lead time of 10 working days from drawing approval.
A torsion spring that wraps around a copper buckle shaft must distribute load evenly across its active coils. If the inner diameter runout exceeds 0.02 mm TIR, the spring will bind against the shaft during rotation, causing uneven wear and premature fatigue failure. In Collection 02, we grind the ends of the shaft pilot and use a dedicated mandrel during coiling to hold concentricity. This is not a generic spring line; every unit is wound on CNC torque-controlled machines that record wire tension per coil, ensuring that the gap between adjacent coils stays within 0.05 mm even after 10,000 cycles.
We start with either music wire ASTM A228 (0.5–4.0 mm diameter) or chrome silicon ASTM A401 (1.0–6.0 mm) depending on your required torque range. For Collection 02, we default to oil-tempered chrome vanadium when the working angle exceeds 180 degrees, because it retains 90% of its load after 1 million cycles. After coiling, we stress-relieve at 260°C for 30 minutes, then shot-peen the outer surface to 0.4 mm depth. The copper buckle shaft itself is not plated by us, but we pre-finish the spring ends with a zinc-nickel coating (6–8 µm) to prevent galvanic corrosion between the copper alloy and the steel wire.
Most torsion spring failures happen at the leg bend, not the coil body. In Collection 02, we use a CNC servo bender with a position feedback of 0.005 mm. Each leg is bent in a single stroke, then optically measured with a profile projector at 20x magnification. If the leg angle deviates by more than 0.5 degrees, we reject the part. We also offer a pre-set leg length option (straight, short hook, or extended torsion arm) where the bend radius is held to 1.0 x wire diameter, eliminating crack initiation points. For prototypes, we can adjust the free angle to ±2 degrees without extra tooling.
We do not assume torque from wire modulus. Each production lot of Copper Buckle Shaft Torsion Springs Collection 02 is sampled at 5 pieces per 500-piece batch. We test torque at 30%, 50%, 70%, 90%, and 100% of the specified deflection angle using a calibrated torsion tester (accuracy ±0.5%). The measured load rate (N·mm/deg) must match your drawing within ±3%. If you need a specific gradient over a 120-degree working range, we pre-set the coil count and wire diameter based on our in-house spring design software, which has been validated against 2,000+ custom spring orders since 2004.
Raw surface finish on the wire is Ra 0.8 µm as-drawn. For direct contact with a copper buckle shaft, we recommend our passivated stainless option (AISI 302) which achieves Ra 0.4 µm and eliminates any need for plating. If you stay with carbon steel, we apply a clear zinc phosphate coating (Ra 0.6 µm) that prevents white rust for 96 hours in salt spray testing. For high-humidity environments, we can add a PTFE impregnation that reduces the coefficient of friction against the copper shaft from 0.18 to 0.08, improving return speed by 15%.
Every single spring in Collection 02 is checked, not sampled. We use a fully automated optical sorting machine that measures free angle, inner diameter, total coils, and leg position in under 2 seconds per part. The machine rejects any unit with a free angle deviation over ±1.5 degrees or an inner diameter variation over +0.02/-0.01 mm. For runout, we use a V-block and dial indicator on 10% of parts, with a hard cap of 0.02 mm TIR. A final inspection report (with CMM data for critical dimensions) is included in every shipment. We also retain a physical master sample for 24 months.
Prototypes (1–50 pieces) ship in anti-corrosion VCI bags inside rigid boxes, with individual foam slots to prevent coil deformation. Production orders (500–50,000 pieces) ship in partitioned cartons with a maximum weight of 15 kg per box to avoid crushing the springs. We offer DHL Express for prototypes (3–5 days to USA/EU) and sea freight for bulk (15–20 days to Los Angeles or Hamburg). All export packaging complies with ISPM-15. For urgent line-down situations, we can air-freight a partial lot within 48 hours at no extra handling fee.
| Parameter | Value / Range |
|---|---|
| Wire Material | ASTM A228 Music Wire, A401 Chrome Silicon, AISI 302 Stainless |
| Wire Diameter | 0.5 mm – 6.0 mm |
| Inner Diameter (ID) | 3.0 mm – 40.0 mm (shaft diameter clearance +0.02 mm) |
| Total Coils | 3 – 20 coils |
| Free Angle Tolerance | ±2 degrees (prototype), ±1 degree (production) |
| Leg Bend Position Tolerance | ±0.01 mm |
| Runout (TIR on ID) | ≤ 0.02 mm |
| Hardness | 44 – 48 HRC (oil-tempered) |
| Surface Finish | Ra 0.4 – 0.8 µm (as-drawn or coated) |
| Operating Temperature | -40°C to +150°C (chrome silicon to +250°C) |
| Max Torque Capacity | 0.5 N·mm to 50 N·m |
| Lead Time | 10 working days (prototype), 20 days (production) |
| MOQ | No MOQ (1 piece accepted) |
No, we accept a single prototype piece for testing, and production pricing kicks in at 500 pieces.
Yes, we offer 100% customization on leg length, bend radius, coil count, and wire diameter, with a 48-hour design feedback loop.
We run a fatigue test on 5 pieces from your lot at 90% of max deflection, and we only release the batch if no permanent set exceeds 0.5 degrees.
We can ship 5,000 pieces in 12 working days if you approve the drawing and material is in stock, but standard is 20 days.
Stop guessing whether a generic spring will fit your copper buckle shaft. Send your 2D or 3D drawing (STEP, DXF, or PDF) to our engineering team, and we will return a firm quote with a torque curve simulation, tolerance analysis, and a suggested material grade within 12 hours. We have 20 years of precision manufacturing experience in Dongguan, China, and we specialize in low-volume, high-tolerance spring work. For more context on how we select tooling for spring coiling, read our CNC cutting tool selection guide, and for understanding how tight we can hold your shaft dimensions, see our CNC machining tolerances guide. No MOQ, no pressure, just a clear answer.
Email: sc@bquq.com
WhatsApp: +86 13713157787
Send your drawing now for a same-day feasibility review.
| Parameter | Capability |
|---|---|
| Materials | SUS302/304/316, SWC piano wire, SWP music wire, 65Mn, phosphor bronze, beryllium copper |
| Types | Compression, extension, torsion, wire forms, battery springs, touch springs |
| Wire Diameter | 0.05 - 12.0 mm |
| Tolerance | ±0.02mm standard, ±0.01mm on request |
| Surface | Zinc plating, nickel, black oxide, passivation, shot peening |
| Machines | CNC spring coiling machines, torsion machines, wire forming machines |
| Prototype | 72 hours, no MOQ on samples |
| Inspection | Load test per batch, fatigue test data on request |
