As a common tool for processing internal threads, taps can be divided into spiral groove taps, blade inclination taps, straight groove taps and tube thread taps according to their shape. According to the use environment, they can be divided into hand taps and machine taps. According to specifications, they can be divided into metric, American, and British taps. Taps are also the mainstream processing tools used in tapping. So how to choose the tap? Today, I will share with you a tap selection guide to help you choose the right tap.
Tapered classification
1 cutting tap
1. Straight groove tap: It is used for the processing of through holes and blind holes. Iron chips exist in tap grooves. The thread quality of the processed is not high, and it is more commonly used for the processing of short chip materials, such as gray cast iron.
2. Spiral groove tap: It is used for blind hole processing with a hole depth of less than or equal to 3D. The iron filings are discharged along the spiral groove, and the surface quality of the thread is high.
The 10~20° spiral angle tap can be processed with a thread depth of less than or equal to 2D;
The 28~40° spiral angle tap can be processed with a thread depth of less than or equal to 3D;
The 50° spiral angle tap can be processed with a thread depth of less than or equal to 3.5D (special working conditions 4D).
Sometimes (hard materials, large tooth spacing, etc.), in order to obtain better tooth tip strength, spiral groove taps will be used to process through holes.
3. Screw tip tap: usually can only be used for through holes, with a length-to-diameter ratio of up to 3D~3.5D. The iron filings are discharged downward, the cutting torque is small, and the surface quality of the machined thread is high. It is also known as a blade inclination tap or apex tap.
When cutting, it is necessary to ensure that all the cutting parts are penetrated, otherwise there will be tooth collapse.
