Auto Lathe Collet & Guide Bushing CNC Machining: 0.003mm Runout, Hardened & Ground, Swiss-Type Ready
Collets on automatic lathes and Swiss-type machines are "precision amplifiers": with 0.003mm collet runout, your turned parts hold roundness at that scale; with 0.02mm runout, even the best machine is wasted. That is why high-end collets are not turned - they are hardened and ground. Material, heat treatment and grinding each fight for microns.
Project Background & Challenge
An automatic lathe and Swiss machine maker wanted to localize imported collets and guide bushings: gripping runout ≤0.003mm, hardness HRC58-62, micron-level bore accuracy and roundness, sizes across types 15-52 plus the ER family, 200 pieces per size initially with rolling supply by machine model.
The challenges: grinding hardened steel at this precision burns or drifts if parameters wander; the elastic-slot geometry directly drives gripping consistency; and many sizes in small batches mean every size must be individually proven - "close enough" does not exist.
BQUQ Process Solution
Turn - Harden - Grind Chain
Bearing steel blanks are turned with grinding allowance, vacuum hardened to HRC58-62, then the bore and faces are ground against the OD datum so internal and external runout stay concentric. Elastic slots are cut by precision wire EDM - slot width and position come from the program, and gripping consistency is supported by both grinding and EDM accuracy.
100% Runout Verification
Every finished collet is bore-measured by air gauge and runout-checked on a dedicated fixture; anything over 0.003mm stays in-house. Hardness and metallurgy are sampled per batch with reports. On size changeovers the first article is fully verified before the batch runs.
Key Specifications
| Item | Specification |
|---|---|
| Material | Bearing steel GCr15 / alloy steel (HRC58-62) |
| Gripping runout | ≤0.003mm |
| Bore accuracy | Micron level, air-gauge 100% inspection |
| Range | Types 15-52, ER series, guide bushings, power chuck pairs |
| Volume | 200 pcs/size minimum, rolling by machine model |
| Inspection | Air gauge + runout fixture 100% + hardness sampling |
| Delivery | Samples 10 days, production 3 weeks |
Quality Control & Delivery
Heat treatment batch and hardness records are archived, grinding parameters are locked per size, and every part is 100% checked for runout and bore with reports included. Samples ship in 10 days; after your machine-side validation, supply rolls by model with 48-hour revision response.
Related Products & Resources
To see more parts in this category and how we scale them, browse the Auto Lathe Collets category page, or these related products:
Related Q&A: What Is Driving the Shift to Higher-Precision Auto Lathe Collets? More Q&A is in our FAQ Center.
For our capabilities, equipment and quality system, visit About BQUQ and Factory Strength.
FAQ
What equipment do you use to hold 0.003mm runout?
Grinding after hardening is the prerequisite - a turned part cannot reach this. The bore is ground against the OD datum for concentricity, slots are wire-EDM cut for consistency, and every part is measured on a dedicated runout fixture. Out-of-spec parts never ship.
How do you stay stable across many sizes in small batches?
Each size gets a full first-article check before the batch, and grinding parameters are documented and locked per size. Size changeovers re-confirm the first article so parameters never cross between sizes.
Can these replace imported collets?
Dimensions are machined per drawing and runout matches import levels. Samples in 10 days - mount one and run a batch of parts to see the difference yourself.
