Views:2802 Author:mayinquan Publish Time: 2019-04-29 Origin:Original
Selection of outer diameter tolerance of cemented carbide bit.
Many cemented carbide bit manufacturers always mark the tolerance of Bit strictly, even require zero tolerance. Not to say zero tolerance does not exist, even the actual drilling hole after the accuracy can not be zero tolerance, because mechanical parts design will consider the difficulty of manufacturing and design the appropriate tolerance. Because the more strict tolerance, the higher the cost of manufacturing, there are data show that the strict tolerance of 0.01 mm, manufacturing costs doubled, required to increase 0.001, manufacturing costs increased 10-20 times, so the price of drill will also increase a lot.
After drilling in a machine shop, it is usually necessary to ream and ream the holes. There is no need to be so strict with the bit tolerance. To put it bluntly, the determination of the bit tolerance is a matter of systems engineering, and the selection of the tolerance takes into account such factors as the combination of processing equipment, processing materials, the acceptable cost of purchasing the bit, the accuracy of the accessories of the machine, and so on. Blind demand for zero tolerance drill production, will only increase their own factory production costs, thus pushing up the cost of parts.
When choosing hard alloy bit, the dimension precision of drilling should be considered firstly. Generally speaking, a drilling molding, drill tolerance should be small. Therefore, the drill bit is usually based on the diameter accuracy of the hole being processed to facilitate the selection of tungsten steel drill bit tolerance. The bit tolerance for secondary machining after drilling can be larger.