Tapping refers to the use of a certain torque to screw the tap into the bottom hole to be drilled to produce an internal thread. "Rigid tapping" is also called "synchronous feed tapping". It is important to choose a suitable lubricant in tapping.
(1) The hole of the threaded bottom hole on the workpiece should be chamfered, and both ends of the through hole thread should be chamfered.
(2) The position of the workpiece clamp should be correct. 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 tap axis is perpendicular to the plane of the workpiece.
(3) At the beginning of tapping, try to position the tap as much as possible, 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 pressure should be applied to the tap, otherwise the thread profile will be damaged.
(4) When tapping, every 1/2-1 turn of the twister should be turned back, so that the chips are easily discharged after breaking, and it can reduce the phenomenon that the cutting edge is stuck by the tap due to sticky chips.
(5) When encountering a screw hole that cannot be tapped, it is necessary to withdraw the tap frequently to remove the chips in the hole.
(6) When tapping the screw holes of plastic materials, add lubricating coolant. For steel materials, engine oil or emulsion with a higher concentration is generally used, and rape oil or molybdenum disulfide with higher requirements is used. For stainless steel, 30# engine oil or vulcanized oil can be used.
(7) When changing to the next tap during the tapping process, first screw it into the tapped thread by hand. When it can no longer screw in, then use the twister to turn it. When the end taper is finished tapping and exiting, it is also necessary to avoid turning the wringer quickly and unscrew it by hand to ensure that the quality of the tapped thread is not affected.
(8) When machine tapping, the tap and the screw hole should maintain coaxiality.
(9) During machine tapping, the calibrated part of the tap can not be completely out, otherwise the tap will have messy teeth when the machine is withdrawn from the tap.
(10) The cutting speed during machine tapping is 6-15 m/min for general 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/min. When the same material is used, the smaller tap diameter takes a higher value, and the larger tap diameter takes a lower value.