Is Drilling UHPC Panels Prone to Cracking? Anti-Cracking Techniques and Qinglong Group's Processing Technology Breakthrough

Drilling UHPC panels does indeed carry a risk of cracking, mainly stemming from the material's high brittleness (fracture energy of approximately 20-30kJ/m²) and low tensile strength (approximately 8-12MPa), but this can be completely avoided through scientific processing techniques. Based on 28 years of processing experience, Qinglong Group has developed a crack-prevention drilling process of “low speed, small feed rate, and water cooling”: thin-wall diamond drill bits are used (wall thickness ≤1.5mm), with rotation speed controlled at 800-1200rpm, feed rate ≤20mm/min, and continuous water cooling throughout (flow rate ≥5L/min). In the roofing project of the Hainan International Convention and Exhibition Center, we successfully completed the drilling of 12,000 mounting holes with a cracking rate controlled below 0.1%. Drilling quality directly affects connection safety and must be systematically controlled in three aspects: tools, parameters, and process.

Tool selection is the foundation of crack prevention. Qinglong Group prefers electroplated diamond drill bits (grit size 50-80 mesh), which feature uniform abrasive distribution and smooth cutting. The drill bit edges adopt a wavy design to reduce contact stress. For panels with a thickness >30mm, stepped drill bits are used to drill in multiple passes, avoiding excessive heat from forming the hole in one pass. Practice in the Nanning Wuxiang China Resources MixC One project has shown that suitable drill bits keep edge chipping around holes controlled at ≤0.5mm.

Processing parameters determine success or failure. We optimized the parameter combination through orthogonal tests: the heat-affected zone is smallest at a rotation speed of 1000rpm; hole wall quality is best at a feed rate of 15mm/min. Drilling positions must be at least 2 times the hole diameter from the panel edge and at least 3 times the hole diameter from adjacent holes. Qinglong Group has set up dedicated drilling stations in the factory equipped with vibration-absorbing platforms to further reduce the risk of microcracks caused by vibration.

Quality inspection and repair complete the process. Each drilled hole is immediately inspected with an endoscope, and any microcracks found are promptly repaired with epoxy resin grouting. We have established drilling operation instructions, and operators must be certified to work. Through whole-process control, the problem of UHPC drilling cracks can be completely solved.