Drilling

Drilling is a <a href="/facts/Cutting/kuSSgehx">cutting</a> process where a <a href="/facts/Drill_bit/DJCVCFA2">drill bit</a> is spun to cut a hole of circular <a href="/facts/Cross_section_(geometry)/g5R1c6v2">cross-section</a> in solid materials. The drill bit is usually a rotary <a href="/facts/Cutting_tool_(machining)/By7NvLuM">cutting tool</a>, often multi-point. The bit is <a href="/facts/Pressure/eyc37GRG">pressed</a> against the work-piece and rotated at rates from hundreds to thousands of <a href="/facts/Revolutions_per_minute/fdNmLToF">revolutions per minute</a>. This forces the cutting edge against the work-piece, cutting off <a href="/facts/Swarf/dlNXhYpd">chips (swarf)</a> from the hole as it is drilled.
In <a href="/facts/Rock_(geology)/FXCJkmop">rock</a> drilling, the hole is usually not made through a circular cutting motion, though the bit is usually rotated. Instead, the hole is usually made by hammering a drill bit into the hole with quickly repeated short movements. The hammering action can be performed from outside the hole (top-hammer drill) or within the hole (<a href="/facts/Down-the-hole_drill/6v4j2x2L">down-the-hole drill</a>, DTH). Drills used for horizontal drilling are called <a href="/facts/Drifter_drill/qfnDfLJL">drifter drills</a>.
In rare cases, specially-shaped bits are used to cut holes of non-circular cross-section; a <a href="/facts/Square_(geometry)/JHJeMvmL">square</a> cross-section is possible.

Drilling open-in-new

Drilling