Specifications
Taps are classified according to their standard, chamfer shape and their flute form
DIN 371
This standard applies to machine taps with reinfored shank to produce metric ISO coarse pitch M1 to M10 according to DIN 13-1.
The standard is based on the dimesional guidlines of the general plan for taps and thread formers according to DIN 2184-1.
DIN 376
This standard applies to machine taps with reduced shank (overflow drill) to produce metric ISO coarse pitch M3 to M68 according to DIN 13-1.
The standard is based on the dimesional guidlines of the general plan for taps and thread formers according to DIN 2184-1.
DIN 374
This standard applies to machine taps with reduced shank (overflow drill) to produce metric ISO fine pitch M3 x 0,2 to M52 x 4 according to DIN 13-2.
The standard is based on the dimesional guidlines of the general plan for taps and thread formers according to DIN 2184-1.
Chamfer
Chamfer is the term used to describe the threads actually cut the thread. Any further threads after the first cut are ony used to guide the tap. Depending on the number of chamfer threads and the respective form of the flute a distinction is made between different chamfer forms and which application they are used for. Longer chamfer forms reduce the stress on the cutting edge but increase the required torque.
| Form | Number of threads of the chamfer | Specification of the flutes | Application |
|---|---|---|---|
| A | 6 - 8 Threads | straight fluted | Clearance holes |
| B | 3,5 - 5 Threads | straight fluted with spiral point | Clearance holes |
| C | 2 - 3 Threads | straight or spiral fluted | Blind hole and clearance hole |
| D | 3,5 - 5 Threads | straight or spiral fluted | Blind hole and clearance hole |
| E | 1,5 - 2 Threads | straight or spiral fluted | Blind hole |
Flute forms
Generally there are four distinguishable types of flutes: straight fluted without spiral point, straight fluted with spiral point, the right hand spiral flute and the left hand spiral flute. The first of the four retaines the chip in the flutes while cutting the thread. The second one cuts the chip with the spiral point so it can exit with the rotational direction. A tap with a right hand spiral point evacuates the chip against the rotaional direction. The left hand spiral point discharges the chip with the rotational direction.
