Bone screws are one of the most demanding deep hole drilling applications I have worked on. They look simple — a threaded shaft with a hole through the middle — but that center hole is the reason I treat every bone screw job with extra care. The diameter range is 1 mm to 4 mm, the lengths go up to 150 mm, and the materials are surgical-grade alloys that do not cut easily. ...
Medical implant drilling is a specialized corner of deep hole drilling. The diameters are small — 1mm to 6mm — and the depth-to-diameter ratios can go to 400:1. The materials are titanium and surgical stainless steel. And the tolerance requirements are tighter than anything else I’ve worked with. The parts I’ve worked on are bone screws, trauma nails, and surgical instruments. They all need a straight, clean hole through the full length. A bone screw that’s 4mm in diameter and 120mm long needs a hole through the center that’s maybe 1.5mm. The wall thickness around that hole is about 1.25mm. There’s no room for error. ...
I’ve covered medical implant drilling elsewhere — this is about micro-hole drilling across all industries. The same principles apply whether you’re drilling fuel injector nozzles, medical components, or cooling channels in electronics. Below 3mm diameter, deep hole drilling changes character. The tools are fragile, coolant flow is restricted, and every parameter matters more than it does at larger diameters. Where Micro-Holes Show Up The industries that need micro-hole deep hole drilling: ...