A gun tap, also known as a spiral point tap, is a cutting tool used to create threads in holes, primarily in metals. It's designed to push chips forward and out of the hole ahead of the tap.
Understanding Gun Taps
Unlike other taps that produce chips, a gun tap shears the material ahead of it, forming a continuous flow of chips that are directed forward, away from the cutting edges. This action makes them particularly effective in through holes and is less likely to cause chip clogging in blind holes, although they are not ideal for blind holes.
Key Features and Benefits
- Forward Chip Evacuation: This is the defining characteristic. The spiral point design forces chips ahead of the tap, preventing them from interfering with the threading process.
- Reduced Torque: Because of the shearing action and forward chip removal, gun taps generally require less torque than standard taps.
- Increased Tap Life: The reduced friction and efficient chip removal contribute to longer tap life.
- Higher Cutting Speeds: Often, gun taps can be run at higher speeds than other tap types.
- Suitable Materials: Commonly used on materials that produce stringy chips, such as aluminum, copper, and some steels.
How a Gun Tap Works
The spiral point (or "gun" point) at the front of the tap is angled to shear the material. As the tap rotates, the angled point creates a chip that curls forward and is pushed ahead into the open space in front of the tap. This leaves the flutes clear and allows the tap to create clean, accurate threads.
Applications
Gun taps are widely used in:
- High-volume production: Their efficiency and longevity make them suitable for mass production.
- Automotive industry: Creating threads in engine blocks, transmission housings, and other components.
- Aerospace industry: Threading various aluminum and alloy parts.
- General machining: Wherever efficient threading of through holes is required.
Comparison with Other Tap Types
| Feature | Gun Tap (Spiral Point Tap) | Standard Tap (Hand Tap) | Spiral Flute Tap |
|---|---|---|---|
| Chip Evacuation | Forward, ahead of the tap | Upwards, into the flutes | Upwards, along the spiral flutes |
| Torque Requirements | Lower | Higher | Moderate |
| Hole Type | Primarily through holes, less suitable for blind holes | Through and blind holes | Blind holes are preferred |
| Application | High-volume production, materials that produce stringy chips | General-purpose tapping, manual tapping | Blind holes where chip evacuation is critical |
| Design | Angled spiral point | Straight flutes | Helical flutes |
