Precision Machining for Long Slender Shafts with Large Flange and Tight Bearing Surface

Slender shafts (L/D >20) with a small diameter, large end flange, and critical bearing surfaces requiring ±5μm tolerances are tough - prone to bending, vibration, and thermal deformation. They are common in precision transmissions and motor spindles.

Here's a proven process to achieve high accuracy (roundness <3μm, Ra 0.2μm):
Unified Benchmark: Drill precise center holes at both ends early—use them throughout for consistency.
Turning Stages: Rough → Semi-finish with one-end chucking + center support. Use follower/steady rests, reverse turning, small depths (0.1-0.3mm), and ample coolant to minimize deflection.
Heat Treatment: Quench & temper, followed by stress relief annealing.
Final Grinding: Center-based cylindrical grinding (rough → fine → superfinish with CBN wheels). For bearing journals, multiple spark-out passes ensure ±5μm tolerance.