What drill is used for machining holes with a diameter of 3mm?
In general, if the drill pointed to the comparison of the grinding, it is recommended to be smaller than the final hole 0.10mm, of course, this is the processing of steel parts, plastic and other processing holes will shrink back, generally take a little larger diameter. If the final size of the strict requirements, it is best to drill rough, such as 2.5 of the drill bit, and then 2.8-2.9 drill reaming, and finally reaming, precision reaming, usually with 3.0mmD5-D6 class. Drill what specifications have, in general, the first series of multi-point, second, third series less, large dosage, you can find manufacturers custom. Can not find the words, you can buy a larger diameter of their own in centerless grinding or grinding on the outer circle to change, but the effect will be worse, the drill has inverted cone, not necessarily grinding, and need experience.
For the steel parts which require fine matching, it is recommended to drill holes with a twist hole smaller than 3mm and then drill with a 3mm bit to ensure the accuracy of the hole. As for plastic, cardboard or copper material, the aperture will be retracted. The drill bits which are slightly larger than the diameter of 0.10mm are generally used. If the machining requirements are strict, it is better to drill rough first. For example: first drill with 2.5mm bit, and then use 3mm bit reaming, so that you can guarantee the accuracy of aperture.
At the same time, it is difficult to guarantee the absolute symmetry of the two main cutting edges because of the small bit. Generally, it is necessary to control the secondary angle of the blade edge at 6 degrees to 8 degrees. The speed is between 1000~1500, and the feed is low, otherwise the drill is easy to break or damage. The emulsion should be cooled during processing.
It is suitable for drilling when holes with smaller processing diameter and less than 4mm are used. Because the processing of small holes, requiring high spindle speed, while the drill bear a great torque.
