Postdrill

Postdrill refers to the set of finishing operations performed after drilling a hole in a workpiece to achieve the required dimensional accuracy and surface quality. The term is used across metalworking, woodworking, plastics, and composite manufacturing, and encompasses processes that prepare a drilled hole for subsequent assembly, coating, or functional use. Postdrill work may occur as part of a single machine cycle or as a distinct secondary operation, depending on production requirements and part geometry.

Common postdrill operations include deburring to remove sharp edges and burrs, chamfering or countersinking to create entry angles, reaming or honing to bring hole diameter closer to specification, and spotfacing for flat seating surfaces. In some cases, postdrill differentiation is done to improve hole roundness, straightness, or edge quality. Dry or wet cleaning steps may accompany mechanical finishing to prevent debris from affecting subsequent operations or finishes.

The choice of tools—deburring blades, countersinks, chamfer mills, reamers, or honing stones—depends on material, hole size, and required finish. In automated environments, postdrill operations are often integrated into CNC programs or robotic workcells, with sensors used to verify hole tolerance and surface finish. Quality control commonly measures diameter, roundness, burr height, and surface roughness to ensure compliance with drawings and downstream processes such as tapping, coating, or fastener assembly.

There is no universal standard for postdrill that applies to all industries; guidelines vary by material and application. Effective postdrill practice balances precision with productivity, considering tool wear, cycle time, and the potential need for post-processing steps like plating or painting.

See also: Drilling, Deburring, Reaming, Chamfering, Countersinking.