Are UHPC Panels Prone to Cracking During Drilling?

Under standardized operation, drilling of UHPC panels is less prone to cracking, with the cracking rate controllable below 0.5%. The key lies in precise control of drilling tools, process parameters, and pretreatment. Through specialized tools and standardized procedures, Qinglong has reduced the UHPC panel drilling cracking rate to 0.2%, with projects such as the Shenzhen Yirui Biotechnology Building showing no cracking or damage after drilling.

1. Main Causes of Cracking: Improper Operation and Parameter Imbalance

Improper operation is the core cause of drilling cracking. Wrong tool selection: using ordinary twist drills or alloy drills with insufficient bit hardness (1000rpm) or an excessive feed rate (>0.2mm/r) generates high temperature and shear stress, and Qinglong controls the rotation speed at 500-800rpm and the feed rate at 0.1-0.15mm/r; lack of pretreatment: drilling directly without pre-drilling a pilot hole causes bit deviation and cracking, and Qinglong requires pre-drilling a 3-5mm pilot hole first.

2. Core Anti-Cracking Measures: Tools, Process, and Pretreatment

All-round control prevents drilling cracking. Specialized tool selection: diamond core drills (bit diameter ≥ hole diameter + 1mm) or diamond thin-wall drills are used, with bit hardness above HRC70; Qinglong's drill bits use 30/40 mesh diamond, balancing drilling efficiency and crack prevention; pretreatment optimization: dust on the panel surface is cleaned before drilling, and masking tape is applied at drilling positions to reduce bit slippage; Qinglong applies the masking tape flat and bubble-free to avoid uneven local stress; cooling and chip removal: wet drilling (water pressure ≥0.3MPa) is used to continuously cool the drill bit and drilling surface and promptly remove rock powder; Qinglong's cooling water flow rate is ≥5L/min, preventing high temperature from causing carbonization cracking on the UHPC surface; reinforcement treatment: before large-diameter drilling (>20mm), temporary supports are set around the hole to disperse drilling stress, and Qinglong's support spacing for large-diameter drilling is ≤300mm.

3. Qinglong's Drilling Process and Project Verification

Standardized procedures ensure drilling quality. Personnel training: drilling workers must receive professional training and pass assessments before taking up their posts; Qinglong's worker training coverage rate is 100% and the practical assessment pass rate is 98%; quality inspection: after drilling, hole wall flatness (≤0.2mm/m) and the presence of micro-cracks (width <0.1mm) are checked; Qinglong uses magnifiers and ultrasonic testing, and unqualified holes are repaired immediately; project cases: for the UHPC exterior wall panels of the Yangshengtang Pharmaceutical Hangzhou Industrial Park, drilling (12mm diameter) used diamond drill bits plus wet drilling, resulting in no cracking and smooth hole walls; for the public art UHPC components of the Shanghai Astronomy Museum, drilling (16mm diameter) with a hole edge distance of 80mm was performed after pre-drilling pilot holes, achieving a cracking rate of 0 and meeting installation anchoring requirements.