This is a CNC Machined Auto Lathe 25 Type Multi Slot Round Bore Collet built for high-volume turning centers and Swiss-type lathes that demand repeatable gripping force. It holds round stock from 3 mm----------
This is a CNC Machined Auto Lathe 25 Type Multi Slot Round Bore Collet built for high-volume turning centers and Swiss-type lathes that demand repeatable gripping force. It holds round stock from 3 mm to 25 mm with a guaranteed runout of ≤0.005 mm, a hardness of 58–60 HRC, and a surface finish of Ra 0.4. You get consistent part concentricity without re-tuning your machine between batches....
Standard collets have three slots. This one has six. More slots mean the bore collapses evenly around the bar, distributing radial force across six contact points instead of three. The result is a 30% higher grip torque on round stock compared to a 3-slot design of the same size. For your auto lathe, this translates directly to fewer rejected parts from axial pull-out during heavy cuts. The round bore geometry is ground in a single pass, not milled, which eliminates the micro-scallops that cause marking on finished shafts.
We start with 20CrMnTi alloy steel, not cheap 45# steel. After CNC machining, we carburize the collet at 920°C and quench it in oil. The case depth reaches 0.8–1.2 mm. Core hardness stays at 35–40 HRC for toughness, while the surface hits 58–60 HRC for wear resistance. This dual hardness profile means the collet springs back to its original bore diameter even after 20,000 open-close cycles. We have tested this in-house on a Citizen L20 lathe with 304 stainless steel bar — no measurable bore growth beyond 0.003 mm after 25,000 cycles.
Every collet bore is ground to a tolerance of H6 or H7, depending on your stock tolerance. For cold-drawn round bar with a standard h9 tolerance, we recommend an H7 bore (0/+0.021 mm for a 20 mm bore). For precision-ground bar (h6), we grind the bore to H6 (0/+0.013 mm). If you are feeding raw extruded aluminum, we can open the bore to H8 to avoid binding. Just tell us your bar tolerance, and we will match the bore class — no extra cost for custom classes within the 25 type range.
Each collet is checked on a custom mandrel with a 0.001 mm dial indicator. We measure runout at the bore mouth and at 25 mm depth. Both readings must be ≤0.005 mm or the collet goes back to the grinding station. Bore diameter is verified with an air gauge, which gives a repeatability of ±0.0005 mm. We also test slot width with a pin gauge — each slot must be within 0.02 mm of nominal. This is not a sampling plan. Every single unit is inspected and a report is attached to your shipment.
The 25 type profile follows the standard DIN 6341 form, so it fits most Japanese and European auto lathes: Citizen, Star, Tsugami, and Tornos. The pull-back angle is 30° standard, but we can machine a 20° or 45° angle if your spindle uses a proprietary taper. The head diameter is 25.4 mm (1 inch) with a length of 80 mm. If you need a different head diameter for a specific spindle nose, we can adjust the blank size before CNC machining — the multi slot pattern is CNC-machined anyway, so non-standard dimensions do not slow us down.
Standard sizes (3, 4, 5, 6, 8, 10, 12, 14, 16, 18, 20, 22, 25 mm) ship in 7 working days. Custom bore diameters or special tapers take 12 working days because we need to order a specific grinding wheel. There is no MOQ — you can order one piece for a prototype or a thousand for a production line. For quantities above 50 pieces, the unit price drops by 18%. We have a 3-shift CNC workshop in Dongguan, so your order never waits for a machine to free up.
| Specification | Value |
|---|---|
| Type | 25 Type Multi Slot Round Bore Collet |
| Material | 20CrMnTi alloy steel (case-hardened) |
| Hardness | 58–60 HRC (surface), 35–40 HRC (core) |
| Bore Diameter Range | 3 mm – 25 mm |
| Bore Tolerance | H6, H7, or H8 (custom) |
| Runout (TIR) | ≤0.005 mm at mouth and 25 mm depth |
| Surface Finish | Ra 0.4 (bore), Ra 0.8 (external) |
| Slot Count | 6 (multi-slot design) |
| Pull-back Angle | 30° standard (20° or 45° custom) |
| Head Diameter / Length | 25.4 mm / 80 mm |
| Lead Time | 7 working days (standard), 12 (custom) |
| MOQ | No MOQ (1 piece accepted) |
No MOQ. We accept a single piece with a custom bore — the CNC program and grinding wheel setup are already configured for the 25 type family, so a custom bore adds no setup penalty.
Yes, we can apply a 0.01 mm hard chrome layer on the bore, which raises surface hardness to 68 HRC and reduces wear from abrasive composites — just note this adds 3 working days to the lead time.
We mount each collet on a precision mandrel with a 0.001 mm indicator and measure TIR at two axial positions; if either reading exceeds 0.005 mm, the unit is rejected and reground.
Standard reorders ship in 5 working days because we keep the most common sizes (6, 8, 10, 12 mm) in semi-finished stock, ready for final bore grinding.
For a firm quote within 12 hours, email your drawing or bore size to sc@bquq.com or message us on WhatsApp at +86 13713157787. Send your drawing and our engineers will confirm the bore tolerance, slot geometry, and pull-back angle for your specific auto lathe model. This precision manufacturing collet is made in China with no MOQ, so your first test piece costs the same as a production run. Before you lock in your tooling plan, check our CNC cutting tool selection guide to match the collet with your insert grades, and review the CNC machining tolerances guide to ensure your part drawings are realistic for the 25 type collet's gripping range. If you are optimizing cycle time, the CNC programming optimization article explains how toolpath strategies interact with workholding rigidity — a 6-slot collet gives you the stiffness to push that envelope.
| 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 |
