With higher integration of granite substrates for CMMs, semiconductor optical platforms and femtosecond laser equipment, demand for through and stepped deep holes keeps rising. Our exclusive 3100kg/m³ high-density granite features outstanding compactness and compressive strength, yet its brittle crystalline structure easily suffers entry chipping, exit corner spalling and hole wall microcracks under feed impact, cutting heat and poor chip removal. Most manufacturers simply slow feed rates to reduce damage, leading to longer lead times and higher tool costs. Leveraging our Class 10,000 constant-temperature clean workshop, Taiwan Nantong CNC grinders and self-built cutting test database, UNPARALLELED's process team has upgraded a graded feed parameter system. Segmented speed regulation, peck drilling and differentiated entry/exit speed control resolve deep-hole breakage fundamentally, enabling defect-free mass production. 
1. Root Causes of Deep-Hole Defects on 3100kg/m³ Granite
Dense crystal arrangement brings uniform internal stress but low impact toughness, causing three typical damages under constant feed:
Vertical plunge impact: Concentrated cutting force tears crystal grains, creating jagged entry chipping.
Chip clogging at deep sections: Depth-diameter ratio over 5:1 traps debris, accumulating heat to form hidden cracks that trigger spalling when the drill breaks through.
Unbuffered exit thrust: Thinning supporting material cannot resist feed force, making corners prone to falling off. Fixed universal feed parameters fail to match varying drilling conditions, resulting in unstable yields below semiconductor and metrology standards.
2. Optimized Hierarchical Feed Parameter System
We develop customized feed libraries by hole size and depth ratio, adopting three-stage variable speed machining tailored to dense granite:
Pilot pre-drilling: Low-speed helical plunging disperses stress to avoid surface chipping.
Peck drilling cycle: Intermittent retraction removes chips and dissipates heat; feed drops 30% on re-entry to lessen impact, with continuous high-purity internal cooling preventing intergranular cracks.
Exit speed reduction: Feed slows gradually when 2–4 mm material remains. Granite backing plates buffer thrust to eliminate corner loss.
Feed rates are adjusted by aperture: slower feed for holes ≤10mm, lower spindle speed and longer retraction intervals for large deep holes. Verified by hundreds of tests, chipping defects drop by 96% without sacrificing efficiency.
3. Auxiliary Process Matching
Custom balanced diamond drills with wide flutes reduce vibration damage; worn bits get replaced timely.
Vibration-isolated Class 10,000 clean workshop and multi-point clamping eliminate extra shaking; clamps avoid hole edges.
Only aged, tested homogeneous granite blanks proceed to drilling to stabilize parameter performance.
4. Application Results
This process is fully applied to semiconductor inspection bases, CMM beds and linear motor stages. It cuts rework time and delivers metrology-standard flatness and roughness compliant with DIN and ASME norms. All four granite production lines and four large grinders store these standardized parameters, supporting custom deep-hole machining for 20-meter super-large workpieces. Stable supplies go to Samsung, Akribis, metrology institutes and labs, simplifying customer assembly and improving precision.
Instead of costly post-polishing for chipping, UNPARALLELED eliminates defects via front-end feed optimization. Our R&D team will cooperate with university labs to build intelligent adaptive drilling parameter systems, refine ultra-precision machining standards, and boost yield and accuracy for global precision and semiconductor industries.