This is the BQUQ Stainless Steel Coil Compression Springs Collection: custom-manufactured coil springs from 302, 316, 17-7PH, and Inconel X-750, made in China with CNC coiling and full grinding. You g
This is the BQUQ Stainless Steel Coil Compression Springs Collection: custom-manufactured coil springs from 302, 316, 17-7PH, and Inconel X-750, made in China with CNC coiling and full grinding. You get a spring that holds ±0.01 mm on outer diameter, free length tolerance of ±0.5%, and a maximum working hardness of 72 HRC (for 17-7PH) — with a standard lead time of 7 days for prototypes and 15 days for production runs. No MOQ, so you can order one piece or one million.
Most spring failures come from inconsistent free length and load drift. Our CNC coiling machines use closed-loop wire feed with laser measurement every 0.1 seconds. This holds free length tolerance at ±0.5% for wire diameters from 0.1 mm to 12 mm. Load at 50% deflection stays within ±3% of your specified value. We verify this on a digital force tester for every batch — not a sample, every spring.
We start with certified wire: AISI 302 (basic corrosion resistance), AISI 316 (marine and chemical), 17-7PH (high strength with 72 HRC max after precipitation hardening), and Inconel X-750 (up to 600°C continuous service). Each coil goes through stress-relief heat treatment at 260–430°C, depending on material. For 17-7PH, we add a precipitation hardening cycle at 480°C for 1 hour. This gives you a spring that does not sag under cyclic load — tested to 1,000,000 cycles at 80% of max stress.
Rough edges cause stress concentration and premature fracture. We grind both ends flat, achieving squareness within 0.5° of the axis. Surface finish on ground ends is Ra 0.4 µm. On the coil body, we offer either passivated (Ra 0.8) or electropolished (Ra 0.4) surfaces. Electropolishing removes 0.002–0.005 mm of surface layer, eliminating micro-cracks from wire drawing. If you need a specific finish for medical or semiconductor use, tell us — we have 8 finish options.
Standard springs come with closed and ground ends. But your application might need something else. We make open ends for dynamic loading, closed ends for static compression, and pig-tail ends for spring guides. We also offer reduced OD ends (for tight bores) and conical springs where each coil nests inside the next. Our engineers will suggest the end type based on your load direction and space envelope — no extra cost for the recommendation.
We do not ship random samples. Every spring is measured for free length, OD, and wire diameter using a vision measuring system (accuracy ±0.002 mm). Load testing is done on a 5 kN universal tester for 5% of each batch. Material certificates come from the mill and include chemical composition and tensile strength. If you order over 5,000 pieces, we include a full inspection report with histograms of the batch distribution. This is standard, not a paid add-on.
Stainless steel still corrodes under salt or humidity. We oil the springs lightly (or use dry film lubricant for cleanroom use) and pack them in anti-static bags with VCI (vapor corrosion inhibitor) paper. For export, we use double-wall cartons with a 15 kg crush strength. If you need individual poly-bagging or color-coded trays for assembly lines, we do that at no extra charge. Each box gets a label with your part number, batch number, and heat number.
Springs alone do not solve assembly problems. If your spring sits in a machined bore or over a shaft, the tolerances must match. Our in-house CNC machining center (20 machines, 4-axis and 5-axis) can produce the mating parts with the same ±0.01 mm tolerance. This means you get a complete assembly — spring and housing — from one factory. For cutting tool geometry that affects spring performance, see our CNC cutting tool selection guide. For general tolerance stacks, read our CNC machining tolerances guide.
| Parameter | Specification |
|---|---|
| Available Materials | AISI 302, AISI 316, 17-7PH, Inconel X-750, Music Wire (optional) |
| Wire Diameter Range | 0.1 mm – 12 mm |
| Outer Diameter Range | 1.0 mm – 150 mm |
| Free Length Range | 2 mm – 500 mm |
| Hardness (max) | 72 HRC (17-7PH), 48 HRC (302/316) |
| Tolerance (OD) | ±0.01 mm (for OD < 10 mm), ±0.02 mm (for OD 10–50 mm) |
| Tolerance (Free Length) | ±0.5% |
| Surface Finish (Ground Ends) | Ra 0.4 µm |
| Squareness | 0.5° max deviation |
| Lead Time (Prototype) | 7 days |
| Lead Time (Production) | 15 days for 10,000 pcs |
| MOQ | No MOQ — order 1 piece for testing |
No MOQ. You can order one spring for prototyping or 100,000 for production — the unit price adjusts based on quantity, but we never refuse small orders.
Yes. Send us the physical sample or a drawing with OD, ID, free length, wire diameter, and load at height — we will reverse-engineer it and produce a spring that meets or exceeds the original spec.
We use 100% dimensional inspection on every piece, load testing on 5% of each batch, and include a material certificate with chemical composition and tensile strength. Our QC process follows ISO 9001:2015.
Prototypes ship in 7 days after drawing approval. Production runs (up to 10,000 pieces) ship in 15 days. For urgent needs, we can expedite to 3 days for prototypes at a 10% surcharge.
Get a firm quote within 12 hours. Send your drawing to sc@bquq.com or message us on WhatsApp at +86 13713157787. Include wire diameter, OD, free length, number of coils, and load requirements — we will reply with a complete price and tolerance analysis.
| 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 |
