CTS Slider Motor Mount in SUS316, 5-Axis Milled in One Setup, 100 Percent CMM Verified

About This Part

This mount carries a small drive motor inside a medical slider mechanism, and its size is the first thing to understand: roughly 28 x 20 x 13 mm overall, with a gate-shaped section that leaves an 11 mm wide U groove across the top. The groove floor is a full-radius R4.0 arc that cradles the motor body, and the U sidewalls that support it are about 3.5 mm thick. A bracket this small with walls this thin leaves no spare material for machining mistakes.

The material adds its own difficulty. SUS316 is gummy and work hardens quickly, so a cutter that dwells skims the surface and hardens it instead of cutting, and the next pass meets a skin that pushes the tool sideways. On thin walls the result is not just a rough surface but a measurable lean: the sidewall bows inward under cutting pressure. The route counters this with small diameter coated tools, light layered finishing passes, and fresh edges, so the 11 mm groove width and the wall thickness both survive to the last pass instead of drifting as the cut progresses.

The hole pattern is where the part earns its tolerance. Two M3 threads run through the base with a locking chamfer at entry, and two 3.5 mm countersunk fixing holes sit on the flanges, arranged so the thread axis and the countersink axes cross at right angles. All of them are positioned to plus or minus 0.05 mm, and the mounting face carries a perpendicularity and position requirement of 0.01 to datum A. Tapping M3 in work-hardened stainless is its own risk: each hole is chamfered first and tapped with fresh taps so a 3 mm tap does not snap inside a nearly finished bracket.

Finishing is medical-grade housekeeping. Every part is deburred under a microscope, because a burr that would be invisible on a large part can shed into a mechanism this size. The parts then go through ultrasonic cleaning in purified water followed by passivation with an electropolish step, which leaves the bright, micro-brushed surface and removes the free iron that would otherwise start corrosion in service. The surface must come out clean and bright, with no burrs, scratches, dents or hard spots, and chamfers default to C0.1 where not otherwise specified.

Nothing on this part is sample inspected; everything is checked. M3 threads are gauged with go and no-go thread plug gauges on every part. The R4.0 groove radius, the perpendicularity and position to datum A, and the countersink positions are measured on the CMM, part by part. A final microscope pass confirms the polished surfaces are free of burrs and handling marks before the parts are packed.