It has always been believed that drilling is performed at low feed and cutting speeds, which was once correct under the processing conditions of ordinary drills. Nowadays, with the advent of carbide drill bits, the concept of drilling has changed.
In fact, choosing the right carbide drill bit can greatly improve drilling productivity and reduce single-hole processing costs. What should we pay attention to when choosing a carbide drill bit?
When choosing a carbide drill bit, the dimensional accuracy requirements of the drilling should be considered. Generally speaking, the smaller the processing aperture, the smaller the tolerance. Therefore, carbide drill manufacturers usually classify drill bits according to the nominal diameter of the hole to be processed. Among the four carbide drill bits, solid carbide drill bits have high machining accuracy (the tolerance range of φ10mm solid carbide drill bits is 0 to 0.03mm), which is the choice for machining high-precision holes; the tolerance range of welded carbide drill bits or replaceable carbide drill bits is 0 to 0.07mm, which is more suitable for hole processing with general accuracy requirements.
When choosing a carbide drill bit, in addition to the drilling accuracy requirements, the stability of the processing machine tool should also be considered. The stability of the machine tool is critical to the safe service life and drilling accuracy of the drill bit, so it is necessary to carefully check the working status of the spindle, fixtures and accessories of machine tool.
Welded carbide drill bits and replaceable carbide drill bits are self-centering geometric edges composed of two symmetrical cutting edges. This high-stability cutting edge design makes them unnecessary to reduce the feed speed when cutting into the workpiece, unless the drill is installed at an angle and cuts into the surface of the workpiece at an angle.
Chip removal is an important issue in drilling. In fact, a common problem encountered in drilling is poor chip removal (especially when processing low-carbon steel workpieces). This problem cannot be avoided no matter what carbide drill bit is used. Processing shops usually use external injection of coolant to assist chip removal, but this method is only effective when the depth of the machined hole is smaller than the hole diameter and the cutting parameters are reduced.
Productivity or processing cost per hole is an important factor affecting drilling. In order to improve productivity, carbide drill manufacturers are working hard to study processing methods that can integrate various operating procedures, and develop drilling tools that can achieve AG feed and high-speed processing.
Replaceable carbide drill bits have good economical efficiency of processing. After the carbide drill bit wears out, the user does not need to replace the entire drill bit body, only the carbide drill bit. The purchase cost is only equivalent to the cost of welding or re-grinding the solid carbide drill bit. Cemented carbide is easy to replace and has high repeatability accuracy.