What Is a Taper Tap?

A tap is a tool for processing internal threads. It can be divided into a spiral tap and a straight-edge tap according to its shape. It can be divided into a manual tap and a machine tap according to the use environment. The origin can be divided into imported taps and domestic taps. Taps are the most important tool for manufacturing operators to machine internal threads.

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Taps are a kind of processing

Within a processing

Machine and

For machining common internal threads on nuts or other machine parts (ie tapping). Machine taps usually refer to high-speed steel molar taps, suitable for use in

Taps are usually single or grouped. Small and medium-sized through-hole threads can be tapped with a single tap at one time. When processing blind holes or large-sized screw holes, group taps are often used, that is, one or more screw holes are sequentially processed with two or more taps. Group taps have equal and unequal diameters

Tap classification

1.Different according to driving: hand tap and machine tap

2. Divided by processing method: cutting tap and extrusion tap

3. According to the processed thread: metric coarse tooth tap, metric fine tooth tap, pipe thread tap, etc.

4. According to its shape, it is divided into straight groove taps, spiral groove taps and screw-tip taps.

5. According to the tapping direction of the tap when in use, it can be divided into a straight tap and an inverted tap.

(1) When tapping, first insert the head cone so that the center line of the tap is consistent with the center line of the drill.

(2) Rotate both hands evenly and press slightly to make the tap enter the knife, no more pressure is needed after entering the knife. (3) Each time the tap is rotated, it is reversed by about 45 ° to cut the chips so as not to block.

(4) Do not increase the rotation force if the tap is difficult to rotate, otherwise the tap will break.

Thread is the most common method for connecting mechanical parts, and taps are the most common tool for machining internal threads. The correct selection of taps for internal threads can ensure the quality of the screw connection and increase the service life of the taps.

1. The end face should be chamfered during tapping; the tap should be coaxial with the hole of the workpiece; the axial pressure should be applied at the beginning of tapping to cut the tap. After a few turns, no axial force is required.

2. After the tap calibration part enters the screw hole, it will return to 1/4, 1/2 circle after every half turn to one turn, so that the chips are broken and then attacked downward; when tapping the through hole, it is necessary to withdraw frequently The tap performs chip removal.

3.When tapping on steel workpieces, add

In order to improve the cutting efficiency of the tap, improve the chip and chip removal conditions, and reduce chipping and breakage, modern taps have a variety of new structures.

Screw-tip tap: The cutting part is ground with a diagonal groove, forming a negative

(1) The opening of the threaded bottom hole on the workpiece must be chamfered, and both ends of the through-hole thread must be chamfered.

(2) The position of the workpiece clamp should be correct, and the center line of the threaded hole should be placed in a horizontal or vertical position as far as possible, so that the tapping can easily determine whether the tap axis is perpendicular to the plane of the workpiece.

(3) At the beginning of tapping, put the tap straight as far as possible, then apply pressure to the tap and turn the twisting hand. When cutting 1-2 turns, carefully check and correct the position of the tap. Generally, when cutting 3-4 turns of thread, the tap position should be correct. In the future, it is only necessary to turn the twisting hand instead of applying pressure to the tap, otherwise the thread profile will be damaged.

(4) When tapping, every 1 / 2-1 turn of the twisting hand should be reversed for about 1/2 turn, so that the chips are easily discharged after the chips are broken, and the phenomenon that the cutting edges are stuck by the cutting edges due to sticky chips can be reduced.

(5) When the tapped hole cannot be tapped, always exit the tap to remove chips in the hole.

(6) When tapping the screw holes of plastic materials, lubricating coolant should be added. For steel materials, generally used motor oil or a higher concentration of emulsified liquid can be used, such as vegetable oil or molybdenum disulfide. For stainless steel, use No. 30 motor oil or sulfurized oil.

(7) When changing to the next tap during the tapping process, first screw the tapped thread into the tapped thread by hand, and when it cannot be screwed again, use a twisted hand to turn it. When the end taper exits, it is also necessary to avoid turning the winch quickly, and it is best to unscrew it by hand to ensure that the quality of the tapped thread is not affected.

(8) During tapping, the taps and screw holes must be coaxial.

(9) During the machine attack, the calibration part of the tap cannot be fully advanced, otherwise the teeth will be chaotic when exiting the tap in the reverse direction.

Oxidation treatment is a surface treatment method in which high-speed steel wire is placed in water vapor at 500-550 ° C to form a Fe3O4 film on its surface. Oxidation treatment is also called high pressure steam treatment.

There are three kinds of iron oxides: FeO, Fe2O3, and Fe3O4. Among them, FeO can only be generated above 570 ° C, so it does not exist in the surface treatment layer of the high-speed steel wire cone. The surface of the tap contains Fe3O4 (black iron) and Fe2O3 ( Red iron), and the latter is not beneficial to the tapability of the tap. After high-quality surface treatment, the tap's treatment layer is Fe3O4 coating, which is beautiful in appearance, blue-black, and the surface thickness is 1-3um.

Oxidation characteristics

The reason why the oxidation treatment can improve the performance of the tap is that the surface layer is porous, has a good absorption of the cooling liquid, and can reduce friction. At the same time, the adhesion between the tap and the material to be cut can be prevented. In addition, the grinding stress remaining on the surface of the tap when removing it is also removed.

However, it should be noted that the film produced by the oxidation treatment cannot increase the hardness of the surface layer of the tap, that is, the film itself does not have abrasion resistance.

2. Scope of application

The oxidized tap has a good effect on cutting materials that are easily bonded, such as stainless steel, cast steel, carbon steel, nickel steel, and chrome steel, and is suitable for almost all steel parts.

However, it should be noted that oxidation treatment does not have a particularly good effect on non-metallic materials such as aluminum alloys, die-cast aluminum alloys, and brass, and may even reduce the cutting performance of taps.

Oxidation is widely used in various types of taps (see the introduction of NORIS taps).

3. Cutting performance

When using a taper tap to process stainless steel (austenitic) workpieces that are prone to adhesion, oxidation treatment can increase the tap life by more than 10 times. This can also be seen from the experimental examples of carbon steel processed by NORIS general taps, and the oxidation treatment significantly improved the tap life.