ROTARY ULTRASONIC MACHINING PREPRESS

Rotary Ultrasonic Machining (RUM) Vector CAM Prepress Guide

Rotary Ultrasonic Machining (RUM) combines rotational diamond grinding with axial high-frequency acoustic micro-hammering (20–40 kHz) to process ultra-hard, brittle materials without edge chipping or micro-cracking.

1. Ultrasonic Micro-Fracture vs Ductile-Mode Grinding

By superimposing high-frequency axial vibration, diamond abrasive grains repeatedly indent and separate from the brittle workpiece. This periodic dynamic impact lowers mean grinding forces by 40–60%, flushes abrasive debris, and maintains sharp diamond grit exposure.

2. Engineering Specifications & Tolerances

3. RUM Vector CAM Toolpath & Core Exit Rules

• Helical Trepanning Toolpaths: Replace plunge drilling with continuous helical ramp interpolation DXF toolpaths at a $0.5^\circ–1.5^\circ$ entry pitch to eliminate center dead-zone forces.
• Bottom Exit Deceleration: Within the final $0.30\text{mm}$ of through-hole breakthrough, reduce Z feed rate by 70% to eliminate edge blowout chipping.
• Acoustic Horn Concentricity: Ensure CNC toolholder runout is calibrated $\le 0.005\text{mm}$ TIR at the diamond grinding rim to avoid acoustic harmonic imbalance.