Machining guidelines - Drilling
Soft plastics like thermoplastics pose special requirements for the drilling tool. This is something you should keep in mind.
Plastics are poor conductors of heat, and also possess a low melting temperature, plus high expansion coefficients. This means care must be taken to ensure rapid removal of chips, since otherwise there may be overheating and dimensional changes in the boreholes and in worst case the drill may even fracture (jamming of the hot drill).