Deep Hole Gun Drilling: Straightness & L/D > 50:1 Ratios
Gun drilling is a deep-hole machining process utilizing a single straight-flute cutter with high-pressure internal through-tool coolant (up to 100 bar) to produce straight, high-precision holes.
Engineering Specifications & Parameters
Diameter Range
1.0 mm to 50 mm
Hole Tolerance
H7 - H8 achievable in one pass
Surface Finish
Ra 0.4 - 0.8 microns
Max Depth Ratio
Up to 100:1 Tool Diameter
Through Coolant Pressure
40 to 120 bar (high pressure)
Gun Drilling Mechanics
Standard twist drills wander and pack with chips at depths exceeding 5x diameter. Gun drills feature a single cutting edge with burnishing pads that continuously burnish the hole wall as it cuts.
Critical Engineering Capabilities
Aspect Ratios: Reliably drills length-to-diameter ratios of 50:1 to 100:1+.
Hole Straightness: Drift is less than 0.1 mm per 1000 mm depth.
Internal Surface Finish: Achieves Ra 0.4 to 0.8 microns in a single pass without reaming.
Hydraulic & Aerospace Fluid Channels
Hydraulic manifold crossing channels, mold water cooling lines, firearm barrels, and turbine shaft oil conduits.
Frequently Asked Questions
How does through-tool coolant prevent drill wander?
High-pressure oil enters through the internal tool conduit, continuously flushes chips out along the external V-flute, and hydrodynamically lubricates the carbide guide pads.
Is a pilot hole required for CNC gun drilling?
Yes, a precision pilot hole (1.5x diameter depth with +0.02/-0.00mm tolerance) is mandatory to guide the gun drill tip before high-pressure coolant engages.
