What Collection 02 Delivers: Tight Tolerance, Hard Steel, Fast Turnaround Heavy Duty Coil Compression Springs Collection 02 is a family of custom-engineered compression springs bu
What Collection 02 Delivers: Tight Tolerance, Hard Steel, Fast Turnaround Heavy Duty Coil Compression Springs Collection 02 is a family of custom-engineered compression springs built for high-cycle,
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What Collection 02 Delivers: Tight Tolerance, Hard Steel, Fast Turnaround
Heavy Duty Coil Compression Springs Collection 02 is a family of custom-engineered compression springs built for high-cycle, high-load applications where standard catalog springs fail. You get wire diameters from 0.5 mm to 12 mm, load tolerances held to ±0.01 mm, and surface finish Ra 0.4 µm or better — all from a factory that ships prototypes in 7 days and production runs in 15 days. Every spring is made in China at our 20-year-old Dongguan facility, and we run no MOQ, so you can order one piece for testing or 100,000 for production.
Wire Diameter Range and Free Length Limits We Actually Machine
Collection 02 covers wire diameters from 0.5 mm (fine instrument springs) up to 12 mm (heavy machinery suspension). Free length can go from 3 mm to 300 mm without special tooling. Outside diameter ranges from 3 mm to 80 mm, with a maximum solid height calculated to ensure no coil bind during full compression. If your design falls outside these numbers, tell us — we have custom coiling machines that handle up to 20 mm wire for special orders.
Materials and Heat Treatment We Use for 45–52 HRC Consistency
We stock three spring-grade alloys: music wire (ASTM A228) for general use, chrome silicon (ASTM A401) for high stress and fatigue, and stainless steel 302 (ASTM A313) for corrosive environments. After coiling, we heat-treat every spring in an inert atmosphere furnace to avoid decarburization. The target hardness range is 45–52 HRC, which we verify on every batch using a Rockwell tester. For chrome silicon springs, we shot-peen to improve fatigue life by up to 30% compared to unpeened parts.
End Coil Grinding and Flatness: How We Achieve ±0.01 mm Load Tolerance
Load tolerance is meaningless if the end coils are not square. We grind both ends on a double-disc grinder, holding flatness to 0.05 mm and squareness to 1 degree. This ensures that when you compress the spring, the load path is axial, not angular. The result: a spring rate tolerance of ±5% on free length and ±10% on load at a specified deflection — both measured on a digital force tester calibrated to ISO 7500-1. For critical applications, we can hold load tolerance to ±3% with 100% inspection.
Surface Finish Ra 0.4 µm and Shot Peening Options
Standard surface finish is Ra 1.6 µm, but for high-cycle applications we offer Ra 0.4 µm via a micro-polishing process. This reduces stress concentration points that cause premature cracking. We also offer shot peening to 0.3 mm depth with controlled intensity per SAE J442. The peening media is conditioned cut wire, not glass beads, so we get a consistent compressive residual stress layer. If your spring runs over 1 million cycles, specify shot peening — it is the difference between 10,000 and 500,000 cycles in our tests.
Inspection Before Every Shipment: Force Test, Dimensional Check, Surface Scan
Every spring in Collection 02 goes through a three-stage inspection before it leaves our floor. First, a digital force tester checks load at 25%, 50%, and 75% of free length. Second, a CMM (coordinate measuring machine) verifies wire diameter, free length, outside diameter, and solid height against your drawing. Third, a surface roughness tester confirms Ra value on the active coils. You receive a full inspection report with each shipment — no extra charge, no hidden cost. If a spring fails any check, it is scrapped, not shipped.
Lead Time and Pricing: Prototype in 7 Days, Production in 15 Days, No MOQ
Prototype springs (1–10 pieces) ship in 7 days from drawing approval. Production runs (any quantity above 10) ship in 15 days. We achieve this because our coiling machines are set up for quick changeovers — average setup time is 45 minutes, not 4 hours. Pricing is quoted per piece based on material, wire diameter, and quantity. Because we control heat treatment and grinding in-house, we do not add third-party markups. A typical quote for 100 pieces of a 2 mm wire, 20 mm free length spring is $0.85 per piece, FOB Shenzhen.
Specification
Collection 02 Capability
Wire diameter
0.5 mm – 12 mm (up to 20 mm on request)
Free length
3 mm – 300 mm
Outside diameter
3 mm – 80 mm
Materials
ASTM A228 music wire, A401 chrome silicon, A313 stainless 302
Hardness
45–52 HRC (verified on every batch)
Load tolerance
±10% standard, ±3% with 100% inspection
Surface finish
Ra 1.6 µm standard, Ra 0.4 µm polished option
End coil flatness
0.05 mm
Squareness
1 degree max
Lead time
7 days prototype, 15 days production
MOQ
No MOQ — order 1 piece or 100,000
What is the minimum order quantity for Collection 02?
No MOQ — you can order a single prototype spring for testing or a full production run, and the per-piece price is adjusted based on quantity.
Can you customize spring ends, hooks, or special shapes?
Yes, we can grind, hook, or form closed ends, open ends, or pigtail ends, and we support custom hook angles and loop shapes per your drawing.
How do you ensure quality control on each batch?
We perform force testing at three deflection points, CMM dimensional checks, and surface roughness measurement on every spring, and we include the inspection report with your shipment.
What is your lead time for a custom spring order?
Prototypes ship in 7 days from drawing approval, and production orders ship in 15 days, regardless of quantity, because our in-house heat treatment and grinding eliminate external delays.
Get a Firm Quote Within 12 Hours — Send Your Drawing
Send us your spring drawing, CAD file, or even a hand sketch with dimensions and load requirements. Our engineers will reply within 12 hours with a firm quote, including material recommendation, heat treatment spec, and delivery date. Email your drawing to sc@bquq.com or reach us on WhatsApp at +86 13713157787. For more context on how our springs pair with cutting tools, see our CNC cutting tool selection guide, and to understand the tolerance limits we hold, review the CNC machining tolerances guide. We are a precision manufacturing partner in Dongguan, China, with 20 years of CNC machining, stamping, and spring production experience — let us prove it on your next spring order.
