What is brush drilling machine?

Some brush blocks(brush bases) are pre-drilled, already with holes, in this case, operator only needs to "tuft" (fill holes with filaments).

But some brush blocks(brush bases) are without holes, in this case, operator will need a drilling machine to drill holes before tufting.

Through the below link, you'll see how the machine drills holes:

http://www.brush-machine.com/Video/CNC-5-Axis-Brush-Drilling-Machine.htm