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
BQUQ Double Torsion Springs Collection 02 | Precision Custom Springs Made in China
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
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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.
How Double Leg Coiling Eliminates Torque Imbalance
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.
Materials and Heat Treatment We Use
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.
Leg Configuration Options for Your Assembly
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.
Inspection Before Every Shipment
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.
Fatigue Life Data for 100,000 Cycle Applications
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
Why Our 10-Day Prototype Lead Time Beats Local Suppliers
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.
Choosing the Right Wire Diameter for Your Torque Requirement
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.
Surface Finish and Coating Options for Corrosive Environments
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.
How to Specify Your Double Torsion Spring on the Drawing
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.
What is the minimum order quantity for Double Torsion Springs Collection 02?
No MOQ—you can order a single prototype spring or a 10,000-piece production run with the same per-piece inspection.
Can you customize the leg shape beyond the standard options?
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.
How do you verify the spring rate matches my drawing?
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%.
What is the fastest lead time for a rush order?
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.
