Tapping
Overview of Tapping
Tapping forms an internal thread in a prepared hole using a cutting or forming tap. It produces large numbers of accurate threaded holes in a short time and is used for parts that will be assembled with screws.
The Basic Motions of Tapping
- Rotation
The tap rotates about its axis. This rotation lets the tap's edges cut or form the material to create the thread. - Feed
As it rotates, the tap advances along its axis. This feed motion forms the thread continuously. - Synchronization
Rotation and feed must be precisely synchronized to match the pitch of the thread being formed.
Tapping Methods at Yamaguchi Nut
- Bent-shank tapping: Used mainly for short nuts. The workpiece is pushed onto a continuously rotating bent-shank tap; the thread is formed as the workpiece passes over the cutting section at the tip, and the finished nut exits from the end of the shank. Because the parts flow in one direction, productivity is high.
- Pitch-feed tapping: Used mainly for blind-hole parts. Cutting taps leave a risk of chips remaining inside the hole, so for blind holes we use forming taps, which produce no chips.
The Tapping Process
- Pilot hole: The hole is formed in advance during cold heading.
- Tap selection: A tap is chosen to suit the thread size, pitch, and material.
- Tap mounting: The tap is mounted in the tapping machine.
- Cutting oil: Cutting oil is used to reduce friction and improve machining performance.
- Tapping: The rotating tap enters the hole and forms the thread.
Advantages of Tapping
- Internal threads are formed quickly and efficiently.
- It works with a wide range of materials and is highly versatile.
- Both manual and automated tapping are possible, so the method can match the production volume. At Yamaguchi Nut, tapping is 100% automated.
Key Points in Tapping
Heat control: Heat generated during tapping affects thread accuracy, so cutting oil is used to keep the temperature under control. This preserves both thread accuracy and tool life.
Tap wear resistance: Tapping is often hard on tools, so taps with high wear resistance are recommended. This keeps the process stable over long runs.
Pilot hole accuracy: If the pilot hole is off in position or angle, thread accuracy suffers and product quality is affected. An accurately placed pilot hole improves clamping force and stability.
Cutting speed: The right cutting speed limits tap wear and improves thread accuracy. Lower speeds are preferable for hard materials.
Cutting oil: A suitable cutting oil reduces friction and protects both tool and material. It also improves the thread finish.
Tool selection: Choosing a tap suited to the material and thread type (forming or cutting tap) is important. The right tool improves both efficiency and quality.
Observing these points improves tapping quality and productivity and keeps the product reliable.