Dental implants and the instruments that place them are machined from titanium and surgical stainless at micro scale. The deep holes involved — internal passages, vent holes, coolant channels in surgical drills — are gundrilled or EDM’d to tolerances that would stop a production line in any other industry.
Ø0.3–3 mmholesImplant / instrument bores
Ti-6Al-4VmaterialELI grade for implants
5–30×DL/DMicro deep holes
Ra 0.2–0.8μmSurface requirement
PRINCIPLE
Where Deep Holes Appear in Dental Devices
Feature
Hole type
Purpose
Implant body vent / slot holes
Small radial passages
Bone ingrowth, flushing
Implant internal connection bore
Blind center bore
Screw seat for the abutment
Surgical drill / burr coolant holes
Through coolant passages
Cool the bone drill, clear chips
Driver / wrench passages
Blind small bores
Drive geometry
💡 Material reality: Ti-6Al-4V ELI is stringy, work-hardens, and grabs the edge at any dwell. Everything that applies to titanium deep hole drilling — low speed, positive feed, high-pressure coolant — applies here, only at diameters measured in tenths of a millimeter.
METHODS
Micro Gundrill vs Micro EDM
Criteria
Micro gundrilling
Micro EDM
Diameter
~Ø0.3 mm+
Ø0.05–0.3 mm
Surface
Clean machined
Thin recast layer (may need removal)
Speed
Fast
Slow
Blind micro holes
Doable with care
Preferred for very small blind holes
Repeats
Excellent on CNC
Good with electrode management
⚠️ Biocompatibility means surface matters: the recast layer left by EDM is often considered unacceptable on implant surfaces — it can flake and is a corrosion/initiation site. When EDM is used, a post-process (electropolish, passivation, abrasive flow) is typical.
PARAMETERS
Micro Gundrilling Titanium
Vc: 15–30 m/min — titanium will not tolerate speed.
Feed: 0.002–0.008 mm/rev at Ø0.5–1.0 mm.
Coolant: 80–200 bar oil, filtered to <10 μm.
Entry: pilot or spot drill; a micro gundrill will not start itself on a curved or hard surface.
Monitoring: spindle load and coolant pressure trended — a pressure spike means a packed micro flute and imminent breakage.
✅ The 10 μm filtration rule: at Ø0.5 mm the flute is barely a hair wide. One 20 μm particle packs it — micro drilling demands filtration the rest of the shop may not have.
QUALITY
Implant-Quality Requirements
Traceability: implants are serialized and fully documented — every hole, every parameter per serial number.
Cleanliness: no coolant residue, no chips, no burrs in an internal passage that touches bone or a screw seat.
Standards: ISO 13485 quality system, ASTM F136 for Ti-6Al-4V ELI; surfaces passivated to spec.
Inspection: micro borescope, air gauging, and functional checks of the internal connection.