2A12-T4 Aluminum Motor Flange, 57 mm Diameter with Square Bore and M3/M5 Pattern

About This Part

This flange connects a motor to its bearing housing, and it does three jobs at once. Its 57 +/-0.05 mm outer diameter locates the joint; a 30 +/-0.05 mm square bore through the center locks rotation between the mating parts; and the hole field carries the fastening. The 2A12-T4 aluminum brings high strength for a part that sees torque and vibration, and the clear anodize keeps the alloy protected in service.

The hole field is dense for a 50 mm face: six 3.50 mm through holes, four M3 and four M5 threads specified with depth callouts, two 3.20 mm locating holes, and a 5.80 mm counterbore pattern at 2.20 mm depth for socket heads. Overall thickness references run 13.50 +/-0.10 mm and 9.60 +/-0.05 mm, with a 2.5 mm section step. Because fasteners approach from both sides, the part is machined symmetrically from both faces, so every thread and bore stays square to its own entry face instead of drifting across the thickness.

The route is straightforward and repeatable: CNC turning of the flange profile, CNC milling of the square bore and pockets, drilling and tapping of the M3 and M4 pattern, then deburring and clear anodize. Unspecified corners break at R0.3 and unspecified chamfers run 0.3 x 45 degree as the drawing's general notes require.

Verification covers the joint quality: micrometer and caliper on the diameters and thickness steps, CMM on the hole pattern position and the bore to OD coaxiality, and thread plug gauges in every tapped hole. A flange that assembles hard in the field is a flange that was never gauged; these are gauged one hundred percent.