Double Torsion Springs Collection 02 is a curated set of custom double torsion spring configurations engineered for high-cycle, high-load applications where single torsion springs fail. We hold leg po
Double Torsion Springs Collection 02 is a curated set of custom double torsion spring configurations engineered for high-cycle, high-load applications where single torsion springs fail. We hold leg position tolerance to ±0.02 mm, coil diameter to ±0.03 mm, and surface finish to Ra 0.8, with a standard lead time of 10 working days for prototypes. Every spring is heat-treated to 45–50 HRC and fully stress-relieved, ensuring zero residual deformation after 100,000 cycles in our fatigue tests.
Unlike single torsion springs that twist around one axis, Double Torsion Springs Collection 02 uses two opposing coils wound in series on the same centerline. This design cancels lateral thrust forces, keeping the spring square to the mounting bore. In our test rig, a 2.0 mm wire double spring sustained 8.5 N·m of torque with less than 0.05 mm of axial drift, compared to 0.3 mm drift on a single spring of equal wire. For your application, this means no binding in slotted housings and consistent force output across the full deflection angle—up to 360 degrees without coil clash.
We stock three wire grades for Double Torsion Springs Collection 02: ASTM A228 music wire (0.2–6.0 mm diameter), EN 10270-1 oil-tempered chrome silicon (0.5–10.0 mm), and 302 stainless steel (0.3–4.0 mm). Chrome silicon is our default for high-torque designs because it holds 45–50 HRC after oil quenching at 870°C, followed by a 400°C temper. Stainless steel springs are passivated and reach 38–42 HRC. We do not use zinc plating unless your drawing specifies it—we prefer black oxide or phosphate for corrosion resistance without hydrogen embrittlement risk.
Double Torsion Springs Collection 02 includes four leg styles: straight torsion (0°), short hook (90°), full loop (180°), and double bend (270°). Leg length is machined to ±0.5 mm, and we can add a radial pre-load by setting the leg angle to ±1 degree. For tight radial spaces, we offer reduced leg diameter—down to 70% of the coil wire diameter—so you can mount the spring in a counterbore without extra clearance. Our CNC coiling machines handle right-hand or left-hand wind, and we can produce mixed-wind double springs where each coil has opposite helix direction.
Every unit in Double Torsion Springs Collection 02 passes a 100% dimensional check on a digital optical comparator, not just a sample. We measure free length, coil OD, leg angle, and total coil count to ±0.02 mm. Hardness is verified with a Rockwell tester on a sacrificial spring from the same batch. Surface finish is checked with a portable profilometer—Ra 0.8 is our standard, Ra 0.4 is available for medical or aerospace parts. We also run a 10-piece torque test at 50% of your specified deflection to confirm the spring rate curve matches your drawing. A full inspection report is included with each shipment.
We have tested Double Torsion Springs Collection 02 variants at three stress levels: 700 MPa, 900 MPa, and 1,100 MPa (corrected for curvature). At 700 MPa, all springs survived 200,000 cycles without fracture. At 900 MPa, survival rate is 98% at 100,000 cycles. At 1,100 MPa, we recommend a shot-peening process—we add this at no cost for orders above 500 pieces. For your high-cycle door hinge or return mechanism, specify the required cycle count on your drawing, and we will select the wire diameter and pre-set to match that life target.
| Specification | Value for Double Torsion Springs Collection 02 |
|---|---|
| Available wire materials | ASTM A228 music wire, EN 10270-1 chrome silicon, 302 stainless steel |
| Wire diameter range | 0.2 mm – 10.0 mm |
| Coil outside diameter | 2.0 mm – 80.0 mm |
| Total coils per spring | 2 – 20 (two independent coils in series) |
| Hardness (chrome silicon) | 45 – 50 HRC after oil quench and temper |
| Hardness (stainless steel) | 38 – 42 HRC |
| Leg position tolerance | ±0.02 mm |
| Coil diameter tolerance | ±0.03 mm |
| Surface finish | Ra 0.8 standard, Ra 0.4 on request |
| Leg angle tolerance | ±1 degree |
| Maximum deflection angle | 360 degrees |
| Prototype lead time | 10 working days |
| MOQ | No MOQ—order 1 piece for testing |
| Standard packaging | Anti-rust VCI paper, individual poly bags, export carton |
Most spring shops quote 3–4 weeks for a custom double torsion spring. At BQUQ, we run CNC coiling machines 24/5, and our in-house heat treatment furnace has a 2-hour turnaround for small batches. For Double Torsion Springs Collection 02, we guarantee a prototype in 10 working days from drawing approval, including heat treatment and inspection. If you are in a design freeze, we can expedite to 5 days for a 15% rush fee. This speed lets you validate your mechanism before committing to production tooling.
Torque output scales with the fourth power of wire diameter. Doubling the wire from 1.0 mm to 2.0 mm increases torque by 16 times, but it also raises the stress at the inner coil. For a target torque of 3.5 N·m at 90 degrees deflection, we recommend a 2.5 mm chrome silicon wire with 6 total coils. This yields a spring rate of 0.039 N·m/degree. If you need a lower rate, increase the number of coils or reduce wire diameter. Send us your torque and deflection angle, and we will calculate the exact wire and coil count for your review.
Bare music wire corrodes within hours in humid conditions. For outdoor or washdown applications, we offer these coatings on Double Torsion Springs Collection 02: black oxide (standard, 48-hour salt spray rating), zinc-nickel plating (120-hour salt spray, 8–12 µm thickness), and PTFE coating (dry film, 0.01 coefficient of friction). For medical or food-grade contact, we use 302 stainless steel with electropolishing to Ra 0.4. Tell us your operating environment, and we will select the coating that meets your corrosion spec without adding unnecessary cost.
On your engineering drawing, include these four dimensions: wire diameter, coil OD, total coils (or free angle), and leg position angles. Also state the direction of wind (right or left) and whether the two coils are wound in the same direction or opposite. If you have a mounting pin, give us the pin diameter, and we will set the coil ID with 0.1–0.2 mm clearance to avoid binding. For complex leg shapes, a DXF or STEP file is best—we can import it directly and program the coiling machine within 4 hours of receiving your RFQ.
No MOQ—you can order a single prototype spring or a 10,000-piece production run with the same per-piece inspection.
Yes, we can CNC bend legs into any 2D profile, including Z-bends, loops, and extended arms, as long as the bend radius is at least 2x the wire diameter.
We test a 10-piece sample on a torque tester at 50% of your specified deflection and compare the measured rate to your theoretical value within ±5%.
Rush orders are shipped in 5 working days with a 15% surcharge, and we confirm the exact ship date before you place the order.
Before finalizing your design, review our CNC cutting tool selection guide to ensure your spring ends are machined correctly, and check our CNC machining tolerances guide to align your drawing callouts with our capabilities. For Double Torsion Springs Collection 02, we are ready to quote your custom design today.
Send your drawing by email to sc@bquq.com or WhatsApp +86 13713157787. We will return a firm quote within 12 hours, including tooling cost, unit price, and delivery date. No MOQ, precision manufacturing made in China.
| 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 |
