Difference between the Internal Coolant Drill and Through Coolant Drill

2025-09-25

Definition

Internal Coolant Drill
A drill with built-in coolant channels inside the body. The coolant flows from the shank through internal passages and reaches the cutting edge, providing cooling and chip evacuation.
Through Coolant Drill
A special type of internal coolant drill where the coolant channels are fully through-hole: coolant enters from the shank → travels inside the drill body → exits directly at the cutting edge through outlet holes.

Key Differences

Aspect	Internal Coolant Drill	Through Coolant Drill
Coolant Channel	Has internal channels	Channels are fully through the drill
Coolant Outlet	Coolant may exit at the tip, along flutes, or other outlets depending on design	Coolant exits directly from the tip holes
Cooling Efficiency	Good cooling, but may vary depending on outlet position	Best cooling effect, coolant directly reaches cutting edges
Chip Evacuation	Effective, depends on coolant pressure and design	Excellent, coolant flushes chips out of deep holes
Applications	General drilling, shallow to medium-depth holes	Deep hole drilling (>5D), hard-to-machine materials (stainless steel, titanium, nickel alloys, etc.)

Easy Understanding

Internal Coolant Drill = General category → any drill with internal coolant passages.
Through Coolant Drill = A more advanced design of internal coolant drill, where coolant flows through and exits at the cutting edge, ideal for deep-hole drilling.

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