Spiral Point Tap vs Spiral Flute Tap: Which One Should You Use?
Spiral-point and spiral-flute taps may look similar, but they control chips in opposite directions. Choosing the wrong geometry can pack chips into the hole, damage threads or break the tap. The first question is therefore simple: is the hole through or blind?
Quick comparison
| Feature | Spiral-point tap | Spiral-flute tap |
|---|---|---|
| Chip direction | Pushes chips forward | Pulls chips back toward the shank |
| Typical hole type | Through hole | Blind hole |
| Core strength | Usually stronger because flute space is smaller | More flute space for chip evacuation |
| Typical concern | Needs space below the hole for chips | Chip load and flute strength must be balanced |
How a spiral-point tap works
A spiral-point tap has angular cutting faces near the chamfer that direct chips ahead of the tool. Because the chips do not need to travel back through the flutes, the tap can retain a relatively strong core. This geometry is commonly used for machine tapping through holes.
There must be sufficient clearance beyond the completed thread for chips. If a hole is actually blind or has very limited bottom clearance, chips pushed forward can become trapped.
How a spiral-flute tap works
A spiral-flute tap uses helical flutes to lift chips out of the hole toward the tap shank. It is commonly selected for blind holes because chips must be removed from the same side the tool entered.
Helix angle, flute form and cutting edge design should match the workpiece material and chip behavior. Long, continuous chips require different control from short, brittle chips. Deep blind holes also demand careful attention to flute capacity and lubrication.
Selection by hole type
Through holes
A spiral-point tap is generally the first geometry to evaluate. Confirm that the drill breaks through completely and that the tool has enough axial clearance to finish the required thread depth.
Blind holes
A spiral-flute tap is generally the first geometry to evaluate. Check drilled-hole depth, required full-thread depth and the tap chamfer length. The drilled hole must leave room for the tap point and any chips that remain.
Workpiece material still matters
Hole type does not make the whole decision. Stainless steel can work-harden and may require a suitable HSS-E material, geometry, coating and cutting fluid. Aluminum may produce long chips and can suffer from built-up edge. Cast iron often produces shorter chips and may use a different flute approach. Always evaluate the specific alloy and hardness.
Common reasons taps fail
- Wrong tap-drill diameter or insufficient drilled depth
- Using a through-hole geometry where chips cannot escape
- Poor alignment between spindle, holder and prepared hole
- Excessive runout or an unstable workpiece
- Incorrect cutting speed, feed synchronization or lubrication
- Reusing a worn tap after thread quality begins to deteriorate
Information needed for tap selection
Provide the thread size, pitch and tolerance class; workpiece material and hardness; blind or through hole; drilled depth and required thread depth; machine and holder type; coolant method; and expected production quantity.
Related products: TiCN-coated HSS-E spiral-point and spiral-flute taps, HSS-E cobalt machine taps M3-M16, and seven-piece coated spiral-flute tap set.
Frequently asked questions
Can a spiral-flute tap be used in a through hole?
It may cut the thread, but it is normally selected when chips need to return out of a blind hole. A spiral-point design is usually more efficient for a suitable through-hole application.
Is a larger helix angle always better?
No. Helix angle changes chip lifting, edge strength and cutting behavior. The best choice depends on the material, hole depth and process stability.
Does coating replace cutting fluid?
No. A coating may reduce friction and wear, but lubrication and cooling requirements still depend on the workpiece and tapping process.
Send your application details to 177Tools for tap selection and quotation support.