1. The position of the workpiece clamp should be correct, and try to make the center line of the threaded hole in a horizontal or vertical position, so that it is easy for tapping to judge whether the axis of the tap is perpendicular to the plane of the workpiece.
2. The hole of the threaded bottom hole on the workpiece should be chamfered, and both ends of the through hole thread should be chamfered.
3. At the beginning of tapping, try to position the tap as much as possible, and then apply pressure to the tap and turn the twister. 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, only need to rotate the twister, and no more pressure on the tap, otherwise the thread profile will be damaged.
4. When tapping, when turning the twister for 1/2-1 turn, it should be reversed about 1/2 turn, so that the chips can be easily discharged after breaking, and it can reduce the phenomenon that the cutting edge is stuck due to sticky chips.
5. When tapping the screw holes of plastic materials, add lubricating coolant. For steel materials, generally used oil or molybdenum disulfide, etc., are used in organic or concentrated emulsions. For stainless steel, 30# engine oil or sulfurized oil can be used.
6. When tapping a screw hole that is not possible, always withdraw the tap to remove the chips in the hole.
7. When changing to the next tap during the tapping process, first screw it into the tapped and thread by hand, and then use the twister to turn it when it can no longer screw in. When the end taper is finished tapping and withdrawing, it is also necessary to avoid turning the wringer quickly. It is best to unscrew it by hand to ensure that the quality of the tapped thread is not affected.
8. When tapping, the tap and the screw hole must be coaxial. The calibrated part of the tap can not be completely out, otherwise it will produce disordered teeth when the tap is withdrawn from the reverse rotation.
9. The cutting speed during machine tapping is generally 6-15 m/min for steel; 5-10 m/min for quenched and tempered steel or harder steel; 2-7 m/min for stainless steel; 8-m/min for cast iron 10 meters per minute. For the same material, the smaller tap diameter takes a higher value, and the larger tap diameter takes a lower value.