Blog Details

Home Blog

The difference between the Long Flute Drill and Deep Hole Drill

The difference between the Long Flute Drill and Deep Hole Drill

2025-10-14

1. Definition

Item	Long Flute Drill	Deep Hole Drill
Definition	An extended version of a standard twist drill with a longer flute, designed for medium-depth holes.	A special drill designed for holes deeper than 10× the drill diameter.
Typical Depth Ratio	Hole depth ≤ 10×D	Hole depth ≥ 10×D, commonly 20×D, 30×D, or even 100×D.

2. Structural Comparison

Item	Long Flute Drill	Deep Hole Drill
Appearance	Similar to a lengthened twist drill; simple overall design.	Usually in gun drill, BTA, or ejector-type structure.
Coolant Hole	Some with internal cooling, some with external cooling.	Must have internal coolant channels; high-pressure coolant enters through the center and exits with chips.
Chip Flute	Extended spiral flutes.	Special single- or double-flute design optimized for chip evacuation.
Cutting Edge	Typically double-edge cutting.	Mostly single-edge cutting for better cooling and chip control.

3. Application Range

Item	Long Flute Drill	Deep Hole Drill
Suitable Hole Depth	Medium-deep holes (5–10×D)	Ultra-deep holes (10–100×D)
Typical Applications	Mold machining, automotive parts, through holes, piping holes.	Hydraulic cylinders, gun barrels, crankshaft oil holes, mold cooling channels, shaft holes.
Machine Requirement	Can be used on standard drilling or machining centers.	Requires dedicated deep hole drilling machines or CNCs with high-pressure coolant systems.

4. Performance Comparison

Item	Long Flute Drill	Deep Hole Drill
Chip Evacuation	Normal	Excellent (high-pressure forced chip removal)
Hole Straightness & Surface Finish	Normal	High precision, superior finish
Machining Efficiency	Relatively high	Lower, but capable of very deep holes

5. Summary Table

Comparison	Long Flute Drill	Deep Hole Drill
Hole Depth Range	≤10×D	≥10×D
Cooling Method	External or internal cooling	Forced internal cooling
Chip Evacuation	Average	Excellent
Accuracy Requirement	General holes	High-precision deep holes
Machine Requirement	Standard machine	Specialized or high-pressure system machine