A drilling is per DIN definition a drilled hole whose diameter is smaller than the thickness of the processed material.
Depending on the application it is possible to process blind and through holes by single-pulse drilling, percussion drilling, with special optics by trepanning or just by cutting the circumference. Another to the trepanning different drill process is the coil or helix drilling where the material is removed by layer without the typical combined drill and cut technology.
Laser drilled holes are not as cylindrical as established from the mechanical processing. Because of the conicity and depending on the demands of drilled holes it is always necessary to specify an acceptable difference between the diameters of the materials inlet and outlet side of the laser beam. For example it is possible to vary the conicity of a drilled hole by using ultra short pulsed laser with trepanning optics in an area between 11° and a negative conicity.
Especially for single-pulse and percussion drilling further information according to acceptable circular shape deviations are required because the power distribution in the focus area is formative for the hole.
The drilling of injection nozzles, the processing of vias in ceramics, glass or silicon wafers for circuit carriers and the production of sieves and filters are typical applications.