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Ultra-Precision Machining of Difficult-to-Machine Materials
Ultra-Precision Machining of Difficult-to-Machine Materials
Difficult-to-machine materials—including semiconductors, laser crystals, engineering ceramics, optical glass, superalloys, and composites—are essential in aerospace, energy, and electronic applications due to their superior mechanical and chemical properties. However, their intrinsic brittleness, hardness, anisotropy, and elasticity pose major challenges for machining, often resulting in surface/subsurface damage, dimensional inaccuracy, and tool wear.
| Material | Method | Route |
|---|---|---|
| Glassy carbon | Nano-scratching & indentation (abrasive machining) | Identified brittle-to-ductile transition; ductile deformation → funnel-shaped fracture → brittle fracture; reducing depth/feed & using fine abrasives improves surface quality. |
| GCr15 steel (bushings) | Flexible rheological polishing | Developed theoretical material removal model (fluid dynamics + tribology); validated with <14% error; achieved Ra = 17.59 nm after 60 min polishing. |
| Si₃N₄ ceramics | Diamond wire sawing | Removal mostly brittle; surface roughness 0.27–0.38 µm (decreases with higher wire speed & lower feed); waviness 0.09–0.21 µm. |
| GCr15 steel | Longitudinal–torsional ultrasonic grinding (LTUG) | Built surface topography prediction model; validated with 13.2% accuracy; optimized parameters yield low Ra and high MRR. |
| SiCf/SiC composites | Ultrasonic vibration-assisted scratching | Fiber arrangement strongly influences forces; ultrasonic vibration reduces scratching forces; improves surface roughness by promoting brittle fracture of fibers and matrix tearing. |
| Stainless steel (304) | Vibration-assisted electrochemical drilling (helical electrode) | Optimized process produced Ø200 µm micro-holes (σ = 3 µm); fabricated arrays; enabled high-precision cutting slits without burrs or thermal damage. |
| Ceramics | Thermal-controlled fracture cutting | Found trajectory deviation due to shear stress distribution; dual-surface heating improves fracture quality; FE model clarified stress mechanisms. |
| Single-crystal Si | Nanosecond pulsed laser cutting + surface erasure | Surface wiping removed heat-affected zones; optimized at 20 passes; achieved high cutting quality with minimal thermal damage. |
| Cemented carbide inserts | Chemical–mechanical synergistic preparation (CMSP) | Optimized slurry (10% abrasive, 10% oxidant, 2% dispersant, pH 8); best plate speed = 90 rpm; swing angle = 6°; improved edge prep consistency. |
#Ceramic# machining/SiC/Diamond/Boron Nitride/#precision machining
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