Aluminum Motor Casing and Motor Housing with 0.008mm Bearing Seat Flatness, 0.01mm Spigot Runout and Milled Cooling Fins

This aluminum motor casing houses a servo motor stator and carries the front bearing seat, the mounting flange and the cooling fins in one machined body. The bearing seat is the dimension that controls vibration: if it is not flat and perpendicular to the spigot, the rotor sits at a slight angle, the air gap becomes uneven, and the motor produces a once-per-revolution hum that no balancing corrects.

We machine the bearing seat, spigot, flange face and bore in one clamping, holding seat flatness at 0.008 mm and spigot runout at 0.01 mm. The casing is cut from 6061-T6, 6082-T6 or 7075-T6 aluminum. Cooling fins are milled to 1.2 mm thickness with a controlled depth, and the flange bolt pattern is drilled from the same datum as the spigot so the motor mounts square to the driven element. Anodizing is applied with the bearing seat, spigot and flange face masked.

1. Drawing and process review. We check wall thickness, fin geometry, bearing seat depth, spigot fit and bolt pattern, then issue a process plan and quotation within one working day.
2. Material verification. Plate or extruded stock is checked against the mill certificate for grade and temper, and 7075 is confirmed for condition.
3. Blanking and stress relief. Blanks are cut oversize and stress relieved so the thin fins and the bearing seat do not distort after the bulk of the metal is removed.
4. Rough turning and milling. The outside diameter, flange and bore are roughed with 0.5 mm allowance, and the fin slots are roughed with a trochoidal path to control heat.
5. Finishing in one setup. Bearing seat, spigot, flange face and bore are finished without releasing the part, which is how flatness, perpendicularity and runout stay inside 0.01 mm.
6. Fin milling and deburring. Fins are finished to 1.2 mm with a controlled depth, then every fin edge is deburred so handling is safe and airflow is not blocked by burrs.
7. Anodizing with masking. Clear, black or hard anodizing is applied with the bearing seat, spigot, flange face and grounding points masked, and the coating thickness is recorded.
8. Inspection and packing. CMM for seat flatness and perpendicularity, runout fixture for the spigot, air gauge for the bore, then tray packing with a first article report.

The front bearing sits on the seat, and the rotor position is set by that bearing. A seat that is out of flat by 0.02 mm tilts the outer ring, which shifts the rotor by a few microns at the air gap. At 3,000 rpm that shows up as a tone at the slot passing frequency, and it is often misdiagnosed as an electrical problem. We check seat flatness on a CMM and confirm perpendicularity to the spigot in the same setup, so the mechanical alignment is removed as a variable before the motor is assembled.

Every dimension is built to your drawing: outside diameter, length, fin count and thickness, bearing seat size and depth, spigot diameter and fit, flange pattern, material grade, anodizing type and colour. One piece is enough to start, with no tooling charge and no setup fee, and the prototype uses the same fixture and inspection plan as the batch. If a feature would add cost without improving function, our engineer returns a DFM note with a practical alternative and waits for written approval before production.

• NDA before drawings. A mutual non-disclosure agreement is signed before models, drawings or samples are released, covering geometry, volume, end use and customer identity.
• No portfolio use. Confidential casings never appear in samples, catalogues, website pages or trade fairs, and photographs require written release.
• Dedicated cell. Sensitive jobs run in a segregated area with named operators; programmes and fixtures are stored under a project code, not the customer name.
• Controlled partners. Anodizing suppliers receive the process specification only, never the assembly drawing or the motor application.
• Internal traceability. Batch records are kept for three years so a quality question can be answered without exposing the design.

• Confirmed dates. Prototypes in 5 to 8 working days, batch orders in 15 to 25 working days after drawing approval, written into the order confirmation.
• Fixed slots for repeat parts. Blanket orders reserve machine time, so the same casing arrives in the same week each month.
• No re-programming. Programmes, fixtures and gauge sets stay on file, removing setup time from the second order onward.
• Early risk notice. If material, fin milling, anodizing or inspection threatens the date, you hear it before the date is missed, with a partial shipment option.
• Dispatch evidence. Photos, inspection report and packing list before shipment; tracking number on the day of dispatch.

• Consumer Electronics: phone, tablet and laptop housings, heat sinks, camera brackets, VR/AR headset structural parts, smart wearable shells
• Automation & Industrial Equipment: automation fixtures, jigs, module frames, transmission sliders, motor mounts, sensor housings, conveyor line parts
• Semiconductor & Vacuum Equipment: vacuum chambers, vacuum fittings, precision equipment bases, thermal isolation and insulation parts, inspection fixtures
• Medical Devices: surgical instrument bases, diagnostic instrument housings, endoscope components, aesthetic device structural parts (medical-grade aluminum and stainless steel)
• Automotive: new energy motor housings, battery end plates, sensor brackets, lamp structural parts, tuning parts, hydraulic valve blocks
• Aerospace & UAV: aircraft structural parts, drone frames, landing gear parts, avionics instrument housings (lightweight precision parts)
• Optics & Photonics: optical lens barrels, lens mounts, light source heat sinks, camera module brackets, inspection optical benches
• Communications: 5G heat dissipation cavities, filter parts, signal adapter structural parts, telecom equipment housings
• Robotics: robot arm joint parts, robot bases, reducer housings, AGV structural parts
• Instrumentation: test equipment housings, precision gauge bases, flow meter parts, laboratory equipment accessories

Each casing is packed in a bubble bag, seated in a custom EPE cavity tray so the bearing seat, spigot and fins cannot rub, then sealed in a moisture barrier bag with desiccant. The tray fits a five-layer export carton printed with part number, quantity and batch code. Sea freight ships on fumigation-free plywood pallets; neutral cartons are available for customers selling under their own brand.

Dongguan Changxinda Precision Technology Co., Ltd is a custom machining manufacturer established in 2008 in Dongguan, China. We operate four-axis and five-axis machining centres, turn-mill combined lathes, CNC lathes and milling machines, employ 90 to 102 people and work to an ISO 9001:2015 quality system. Over 200 customers have been served, 50 to 60 percent of output is exported, and annual sales sit between USD 10 million and 20 million. Our engineers work from customer drawings rather than a fixed catalogue, so a motor casing with a bearing seat callout and a fin pattern is standard work for us.