## Opening
Your ER20 collet set starts as raw bar stock, not a catalog blank. We machine every taper, slot, and thread to your drawing. Before shipment, each collet is checked on a CMM and a test ma
## Opening Your ER20 collet set starts as raw bar stock, not a catalog blank. We machine every taper, slot, and thread to your drawing. Before shipment, each collet is checked on a CMM and a test mandrel. You get parts that grip true, run concentric, and hold tolerance under production load.
## Specifications We run ER20 collets on 5-axis CNC turning centers and grinding machines. Each part goes through the same process: turn, grind, slot, heat treat, finish grind, inspect. Hardness is checked on every batch, not every hundredth part.
| Parameter | Value |
|---|---|
| Material | 65Mn spring steel, 20CrMnTi, or 9Cr18 stainless (per your spec) |
| Hardness | HRC 45–52 (spring steel), HRC 50–55 (alloy steel) |
| Taper angle | 8° per side, ground to ±0.002 mm |
| Bore tolerance | H6 or H7, depending on drawing |
| Slot width | 0.8–1.2 mm, EDM wire-cut |
| Surface finish | Ra 0.4 µm on taper, Ra 0.8 µm on body |
| Concentricity | ≤0.005 mm TIR at 3 mm from nose |
| Heat treatment | Vacuum quench + temper, scale-free |
| Process | CNC turning, centerless grinding, wire EDM, heat treat |
| Batch size | 1 to 5,000 pieces, no setup penalty for small lots |
| Inspection | CMM, hardness tester, optical comparator, test mandrel |
We do not skip the grind step. Many shops cut the taper on a lathe and call it done. That gives you runout at the tool tip. We grind after heat treat, so the taper stays true even after the metal moves during hardening.
## Three reasons buyers send us their drawings 1. Batch-traceable quality. Every collet gets a heat number and a batch code. If you find an issue six months later, we pull the records and tell you the exact melt, heat treat cycle, and inspector. No guesswork.
2. Inspection report per batch. You do not have to trust us. Each shipment includes a dimensional report with actual measured values for taper angle, bore size, slot width, and concentricity. Hardness readings are listed per piece, not per lot average.
3. One factory for CNC + stamping + spring + heatsink. Your collet chuck assembly might need a stamped retainer nut, a compression spring for the release mechanism, or a heatsink for a motorized spindle. We make all of those under one roof. One purchase order, one quality system, one shipping date. No juggling three suppliers.
If you are building a spindle or retrofitting a machine, send us your drawing. We have made collets for 20 mm to 20 mm shank tools, plus custom bore sizes for non-standard blanks.
## Questions buyers ask before ordering Q: What is your MOQ? A: No MOQ. We accept one-piece orders for prototypes and ramp up to thousands. Tooling cost is only charged if the part requires a special form tool or fixture. Standard ER20 sizes have no tooling charge.
Q: How do you guarantee tolerance and quality? A: We grind the taper and bore after heat treatment, not before. Every collet is measured on a CMM and tested on a mandrel. The inspection report shows actual values, not just a pass/fail stamp. If a part is out of spec, it does not ship.
Q: What is your lead time for custom collets? A: Standard ER20 sizes ship in 7–10 days. Custom bore diameters or special slot patterns take 12–15 days, including heat treatment and grinding. For urgent jobs, we can split the batch and ship the first pieces in 5 days.
Q: Can you provide material certificates? A: Yes. Each batch comes with a mill certificate for the raw material, heat treat reports with actual hardness curves, and a dimensional inspection report. All documents are in English and traceable to the batch code.
## Send your drawing We quote within 12 hours, not next week. Send your drawing and specify quantity, material, and required hardness. You get a firm price with no hidden tooling or setup fees.
Email: sc@bquq.com WhatsApp: +86 13713157787
We are a precision manufacturing factory in Dongguan, China, with 20 years of CNC machining, stamping, spring, and heatsink experience. Your custom CNC collet chuck is made in China, but it is built to your numbers — not to a cheap catalog spec. No MOQ, no excuses, just parts that run true.
Looking for a different part? We also machine Custom CNC Machined ER32 Collet Chuck with Spanner Wrench | BQUQ in the same Dongguan factory.
| 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 |
