What This Chuck Does in One Line: Zero-Slip Grip for Bar Work up to 55 mm This is a CNC machined auto lathe 55 type round bore spring collet chuck, built for high-speed bar feeding and secondary mac
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What This Chuck Does in One Line: Zero-Slip Grip for Bar Work up to 55 mm This is a CNC machined auto lathe 55 type round bore spring collet chuck, built for high-speed bar feeding and secondary mac
This is a CNC machined auto lathe 55 type round bore spring collet chuck, built for high-speed bar feeding and secondary machining on Swiss-type or automatic lathes. It holds round stock from 3 mm to 55 mm with a guaranteed runout of 0.005 mm TIR (total indicated reading) at the nose, and a surface finish of Ra 0.4 µm on the bore. You get repeatable clamping force of 80–120 N·m, a hardness of 58–60 HRC on the gripping surface, and a standard lead time of 15 working days for custom sizes. No shims, no adjustment—just insert the bar, clamp, and cut.
Serrated collets crush thin-walled tubing and leave marks on finished shafts. Our round bore design distributes clamping force evenly across 360 degrees. The bore is ground after heat treatment, not before, which eliminates distortion. For a 20 mm tube with 1 mm wall thickness, you will see less than 0.01 mm ovality after clamping. This is why precision manufacturing engineers spec this chuck for hydraulic fittings, sensor housings, and medical device components.
We use 20CrMnTi alloy steel for the body and 9SiCr for the collet fingers. 20CrMnTi carburized to a depth of 0.8–1.2 mm gives a surface hardness of 58–60 HRC with a tough core of 35–40 HRC. The 9SiCr fingers are hardened and tempered to 60–62 HRC for wear resistance. This combination stops the chuck from cracking under repeated high-speed clamping cycles (up to 6,000 rpm). If you need stainless steel or Inconel variants, we can machine those on request, but lead time moves to 20 days.
The collet has 12 precision-cut slots, not 6 or 8. More slots mean lower individual finger deflection and better concentricity. We wire-cut the slots, then hand-deburr and grind every edge to a 0.05 mm radius. The spring temper is set at 420 °C for 2 hours, giving a fatigue life of 500,000 open-close cycles without losing grip force. We test every batch to 100,000 cycles before shipping—if a collet fails early, we replace it free.
Here is the full mechanical data sheet. All values are measured at 22 °C, 45% humidity, with a calibrated Mitutoyo CMM.
| Parameter | Value |
|---|---|
| Collet type | 55 Type round bore spring collet |
| Clamping range (round stock) | 3 mm – 55 mm |
| Body material | 20CrMnTi (carburized) |
| Finger material | 9SiCr (hardened) |
| Surface hardness | 58–60 HRC (body), 60–62 HRC (fingers) |
| Runout (TIR at nose) | 0.005 mm max |
| Bore surface finish | Ra 0.4 µm |
| Clamping torque range | 80–120 N·m |
| Max spindle speed | 6,000 rpm |
| Lead time (standard) | 15 working days |
| MOQ | No MOQ—single piece accepted |
We do not use AQL sampling. Every single chuck goes through a 5-point inspection: (1) hardness test on the nose, (2) bore diameter with a bore gauge, (3) TIR runout on a precision mandrel, (4) surface finish with a profilometer, (5) a functional open-close test at 3,000 rpm. The final report is emailed to you with the shipment. If any value exceeds the table above, the part is scrapped—not reworked. This is our standard for all precision manufacturing out of our Dongguan factory.
No MOQ—you can order a single custom-bored chuck, and we will machine it to your drawing within 15 working days.
Yes, we can wire-cut the bore to hex, square, or keyed profiles, but the round bore version offers the best runout spec—0.005 mm TIR vs. 0.01 mm for shaped bores.
Each chuck gets the same 100% inspection protocol, and we provide a material traceability certificate with heat numbers for the 20CrMnTi and 9SiCr steel.
For 200 pieces of standard 55 type round bore chucks, we ship in 20 working days; for custom bores, add 5 days for tooling setup.
Send your drawing or a simple sketch with bore size, stock diameter, and spindle model. Our engineers will reply within 12 hours with a firm price, exact lead time, and a DFM (design for manufacturability) note if we see a risk. For a faster response, include your target tolerance and annual volume. We are a made-in-China factory with 20 years of CNC machining experience, and we ship worldwide via DHL or FedEx. Email your drawing to sc@bquq.com or WhatsApp us at +86 13713157787. For cutting parameters, check our CNC cutting tool selection guide; for tolerance stack-up advice, read the CNC machining tolerances guide.
| Parameter | Capability |
|---|---|
| Materials | AL6061/7075, SUS303/304/316, 45# steel, T2 copper, H59 brass, POM, PEEK, nylon |
| Tolerance | ±0.005mm standard, ±0.003mm on request |
| Machines | 3/4/5-axis CNC, turn-mill, Swiss lathe |
| Surface | Anodizing, nickel, zinc, passivation, sandblast, polish |
| Size Range | Max 400 x 300 x 200 mm |
| Prototype | 72 hours, no MOQ on samples |
| Inspection | Full report per batch, CMM data on request |
