Tapping: Making internal screw patterns is called tapping, and its tool is called thread tapping.
Threading: Making external threads is threading, and the tool is a wrench.
Key points of tapping:
(1) The hole opening 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, and the centerline of the threaded hole should be placed in a horizontal or vertical position as much as possible, making it easy to determine whether the tap axis is perpendicular to the plane of the workpiece during tapping.
(3) At the beginning of tapping, try to align the tap as much as possible, then apply pressure to the tap and rotate the wrench. When cutting 1-2 turns, carefully check and calibrate the position of the tap. When cutting into 3-4 threads, the position of the tap should be correct and error free. In the future, only the twisting hand needs to be turned instead of applying pressure to the tap, otherwise the thread shape will be damaged.
(4) When tapping, for every 1/2-1 turn of the wrench, it should be reversed about 1/2 turn to make it easier to discharge the broken chips and reduce the phenomenon of the cutting edge being stuck by the tap due to chip sticking.
(5) When the screw hole cannot be penetrated, the tap should be frequently withdrawn to remove chips from the hole.
(6) When attacking the screw holes of plastic materials, lubricating coolant should be added. For steel materials, vegetable oil or molybdenum disulfide can generally be used for those that require high concentration emulsions or are not available. For stainless steel, 30 # engine oil or sulfurized oil can be used.
(7) When replacing the last tap during the tapping process, it is necessary to manually screw it into the already tapped and threaded thread until it can no longer be screwed in, and then use a wrench to turn it. When exiting after the final cone attack, it is also necessary to avoid rapid rotation of the twisting hand. It is best to use your hand to unscrew it to ensure that the quality of the already drilled thread is not affected.
(8) During machine tapping, the tap and screw hole should maintain coaxiality.
(9) During machine tapping, the calibration part of the tap cannot be fully pointed out, otherwise it will produce messy teeth when reversing and exiting the tap.
(10) The cutting speed during machine attack is generally 6-15 meters per minute for steel materials; Quenched and tempered steel or harder steel is 5-10 meters per minute; Stainless steel is 2-7 meters per minute; Cast iron is 8-10 meters per minute. When using the same material, a smaller tap diameter is taken as the higher value, and a larger tap diameter is taken as the lower value.
