Crossdrilling

Crossdrilling is a machining technique in which holes are drilled through a component in a direction that intersects an existing bore or internal passage. The resulting cross passages allow fluid, gas, or lubricant to flow between passages, to relieve pressure, or to permit cooling or lubrication at bearing surfaces. The technique is widely used in automotive, aerospace, and machinery to create interconnections between galleries, channels, or ports without requiring additional assemblies.

Common applications include crossdrilled brake rotors, where holes pass through the rotor face to improve heat dissipation and reduce brake fade; crossdrilled oil passages in engines and crankshafts to supply lubricant to bearings or cams; and cross passages in hydraulic components to connect separate fluid channels or to vent air.

Manufacturing considerations include precise alignment with the main bore to avoid misdrilling, control of hole diameter and depth, and post-drilling finishing such as deburring and chamfering. Heat treatment after drilling may be required to relieve residual stresses. Improper crossdrilling can introduce stress concentration and crack initiation, reducing fatigue life, especially in high-stress components. Sealing and lubrication must be considered to prevent leakage at cross holes.

Advantages include improved cooling and lubrication, potential weight savings, and, in braking contexts, reduced vapor buildup. Disadvantages include potential weakening of the parent material, risk of crack propagation, added manufacturing cost, and the potential for leaks if not properly sealed.

Notable examples include crossdrilled brake rotors used in performance vehicles, and oil- or coolant-cross passages in internal combustion engines. The term may also apply to cross passages in plumbing or hydraulic manifolds.