OpeningYour drawing defines the spring. We build it exactly to that spec. Every custom extension tension spring is made from your CAD, PDF, or sample. We verify dimensions and load
Custom Zinc Plated Extension Tension Springs | Precision Made in China, No MOQ
OpeningYour drawing defines the spring. We build it exactly to that spec. Every custom extension tension spring is made from your CAD, PDF, or sample. We verify dimensions and load before shipment. No
Get a Fast Quote for This Part
Send us your drawing / quantity / material — reply within 24h.
Your drawing defines the spring. We build it exactly to that spec. Every custom extension tension spring is made from your CAD, PDF, or sample. We verify dimensions and load before shipment. No guesswork.
We run a 20-year-old precision manufacturing factory in Dongguan, China. Our spring line is separate from our CNC and stamping lines. That means dedicated machines, dedicated tooling, and dedicated QC for your parts.
Tolerance: ±0.05 mm on wire diameter, ±0.1 mm on free length
Lead time: 7–12 days for prototypes, 15–20 days for production
No MOQ – order 10 pieces or 100,000
Zinc plating: 8–12 µm thickness, salt spray test 48 hours minimum
Material certs and full inspection report included with every batch
Specifications
Parameter
Value
Notes
Wire diameter
0.1 – 12.0 mm
Cold drawn spring steel, stainless, music wire
Free length
5 – 500 mm
Measured unloaded, per drawing
Outside diameter
1.0 – 80.0 mm
Tolerance ±0.1 mm
Total coils
3 – 100
Custom per load requirement
Load tolerance
±5% at specified deflection
Verified on calibrated test rig
Surface treatment
Zinc plating (blue/clear/yellow), or as specified
8–12 µm, RoHS compliant
Material grades
SWP-B, 302/304/316 stainless, 65Mn, 60Si2MnA
Cert available per heat
Machines
CNC coiling, automatic spring forming, tension hook bending
Up to 0.02 mm repeatability
Inspection
100% dimension check on critical features, batch sampling for load
Report per batch
Batch traceability
Heat number, machine ID, operator ID, date stamped on label
Full trace to raw material
We do not outsource plating. The zinc line is in-house, so you get one vendor, one quality standard, one delivery.
Three reasons buyers send us their drawings
1. Batch-traceable quality. Every spring gets a batch number. That number ties to the raw material heat, the coiling machine, the operator, and the plating bath. If a problem shows up in your assembly line, we trace it in minutes, not days. You get a written record for your own QA file.
2. Inspection report per batch. We do not just say "it's fine." You receive a PDF with measured dimensions, load test results, surface finish check, and salt spray test data. The report is signed by our QC lead. If you need third-party inspection (SGS, BV), we coordinate that too.
3. One factory for CNC, stamping, springs, and heat sinks. Your spring often sits next to a stamped bracket or a CNC-machined housing. Send us the whole assembly. We make all parts under one roof. That kills tolerance stack-up issues and cuts your supplier management time. One PO, one delivery, one responsible party.
Where these parts are used
Zinc plated extension tension springs are not decorative. They do work. Real applications we ship to every month:
Automotive: brake pedal return springs, clutch linkage springs, latch mechanisms. Zinc plating resists road salt and humidity.
Industrial equipment: conveyor tensioners, counterbalance systems, gate openers. Needs consistent load over thousands of cycles.
Medical devices: instrument return springs, adjustable bed mechanisms. We use 302 stainless for these, but the same tooling and QC applies.
Agriculture: planter mechanisms, baler tension springs. Dust and moisture exposure – zinc plating is the standard.
Consumer products: trampoline springs, garage door tension springs, exercise equipment. High cycle life, consistent pull force.
If your application needs a specific load at a specific length, we calculate the wire diameter and coil count from your requirements. You do not need to guess. Send the drawing or the working envelope, and we design the spring for you.
Q: What is your MOQ?
Zero. No minimum. We run prototypes of 10 pieces and production of 100,000 on the same machines. Tooling cost is amortized into the piece price for large orders; for small orders, you pay a small setup fee. That is it.
Q: How do you control tolerance and quality?
We measure free length, outside diameter, and hook angles on 100% of parts. Load testing is done on a 5% sample per batch, or 100% if you require it. Our CNC coiling machines hold ±0.05 mm on wire feed. Plating thickness is verified with a digital gauge. You get the report.
Q: What is your lead time?
Prototype springs ship in 7–12 days after drawing approval. Production runs ship in 15–20 days. For repeat orders with no design change, we can hold safety stock and ship in 5 days. Air freight from our door to yours takes 3–5 days depending on destination.
Q: Can you provide material certificates?
Yes. Every batch includes a mill certificate for the raw wire, showing chemical composition and mechanical properties. We also provide a plating certificate with thickness and salt spray test results. If your customer requires it, we can add a notarized certificate of origin for made in China goods.
Send your drawing
Do not design in a vacuum. Send us your spring drawing, a sketch, or even a physical sample. We will reverse-engineer it, confirm the load and dimensions, and give you a firm quote in 12 hours.
Email: sc@bquq.com
WhatsApp: +86 13713157787
We reply within one business hour. No sales script, just engineering answers. Your drawing is safe with us – we sign NDA on request. Precision manufacturing is our core, custom springs are our specialty, and made in China is not a compromise when the QC is this tight.
