A housing can pass every dimension on the drawing and still let the stator rotate under torque. The usual cause is a bore that is round at the ends and bell-mouthed in the middle: a boring bar deflects through a deep bore, and the three-point measurement at the mouth reads nominal. The other cause is bearing seats bored from opposite ends, which puts the rotor 0.03 mm off axis and preloads both bearings.

This housing is bored in one pass on a rigid boring head with a finish pass at low radial engagement, then measured for cylindricity along the full stack length rather than at the ends. Both bearing seats are line bored in the same setup, so front and rear share one axis before anodizing, with those faces masked so coating never changes the fits.

• Full-length cylindricity — 0.01 mm measured through the stack, not at the mouth.
• One bore line for both seats — 0.008 mm coaxiality front to rear.
• Press fit that stays put — H7 bore plus a controlled interference band, verified on a test stator.
• Coating kept out of fits — bore and seats masked, so 15-20 µm of anodizing never eats the interference.

1. Fit review — stator OD, bearing part numbers, interference band and stack length confirmed against your motor build sheet.
2. Material verification — 7075-T5 received by heat number, ultrasonic checked, 3.1 certificate retained.
3. Rough turning — OD and bore roughed with 0.8 mm allowance, material removed symmetrically to limit distortion.
4. First stress relief — low-temperature relief so the thin wall does not close in after boring.
5. Semi-finish — OD and bore semi-finished with light radial engagement, wall thickness checked in process.
6. Second stress relief — a second cycle before the final boring pass, keeping the bore round through the stack.
7. Finish boring — stator bore finished to H7 Ø48 with a low-deflection boring head, cylindricity verified through the length.
8. Bearing seats — front and rear seats line bored in the same setup to 0.008 mm coaxiality, phase slots milled after boring.
9. Anodizing and verification — bores masked, 15-20 µm anodizing, CMM report and FAI shipped with the parts.

• Stator interface — press fit, thermal fit, or bonded with a retention shoulder.
• Bearings — deep groove, angular contact, or ceramic hybrid seats with preload shims.
• Cooling — plain wall, finned OD, or a coolant jacket with an O-ring seal land.
• Wire exit — axial slots, radial grommet, or a sealed connector boss.
• Sampling — 1 pc pressed onto a sample stator for an interference check, then volume.

Motor geometry, stator stack and winding data are competitive information, so access is limited from the drawing stage onward.

• NDA first — mutual NDA and non-circumvention signed before any file is exchanged.
• Isolated area — dedicated machines and authorized staff, no phones or photography inside.
• Codified routing — internal codes on travelers and labels instead of your part numbers.
• Data control — per-project folders on a permission server, destroyed on request with a record.
• No display — no drawings, part photos or logos in samples, catalogs, the website or social media.

Dongguan Changxinda Precision Technology Co., Ltd. — founded in 2008, 90-102 staff, ISO 9001:2015 certified, annual sales USD 10-20 million, export share 50-60%, serving customers in Europe, North America, Japan and Southeast Asia.

Machining, stress relief, anodizing and metrology run in one plant: 5-axis and 4-axis machining centers, turn-mill centers, surface grinders, wire EDM, CMM, 2.5D vision metrology and automated anodizing lines. About 12,000 aluminum parts ship each month, most of them small precision parts where the fixture and the boring sequence decide the result.

1. 01 Consumer Electronics — Phone, tablet and laptop housings · heat sinks · camera brackets · VR/AR headset structural parts · smart wearable housings
2. 02 Automation & Industrial Equipment — Automation jigs · fixtures · module frames · transmission sliders · motor mounts · sensor housings · conveyor line components
3. 03 Semiconductor & Vacuum Equipment — Vacuum chambers · vacuum fittings · semiconductor equipment precision bases · thermal insulation parts · inspection fixtures
4. 04 Medical Devices — Surgical instrument bases · medical device housings · endoscope components · aesthetic equipment structural parts (medical grade aluminum / stainless steel)
5. 05 Automotive — EV motor housings · battery end plates · sensor brackets · lamp structural parts · aftermarket parts · hydraulic valve blocks
6. 06 Aerospace & UAV — Aircraft structural parts · UAV frames · landing gear components · avionics instrument housings (lightweight precision parts)
7. 07 Optics & Photonics — Optical lens barrels · lens mounts · light source heat sinks · camera module brackets · inspection optical stages
8. 08 Telecommunications — 5G heat sink cavities · filter housings · signal adapter brackets · telecom equipment enclosures
9. 09 Robotics — Robotic arm joint parts · robot bases · reducer housings · AGV chassis structural parts
10. 10 Instruments & Meters — Inspection equipment housings · precision gauge bases · flow meter parts · laboratory equipment components

Two shifts 07:30-22:00, six days a week, with weekend shifts in peak season. Capacity is locked weekly for volume programs, so a rush order never displaces a scheduled batch.

• Samples — 7-10 days, checked on your stator or bearing set before the batch is released.
• Batch — 15-20 days from deposit and drawing approval.
• Buffer stock — semi-finished stock for repeat models, cutting repeat lead time by about 30%.
• Shipping — DHL/FedEx/UPS in 3-5 days for samples; air or sea for volume; EXW Dongguan, FOB Shenzhen or CIF.
• Documents — FAI, 3.1 material certificate, CMM report and packing list with every shipment.

Send STEP / IGES / DWG / PDF and receive DFM feedback plus a formal quotation within 24 hours.

Dongguan Changxinda Precision Technology Co., Ltd. · ISO 9001:2015 · Dongguan, Guangdong, China