Hollow drill bit is also called core drill bit, hole opener, hollow cutter, magnetic seat drill bit, magnetic drive drill bit, etc. The working principle of hollow drill bit is: two or more groups of three blades are combined, and the three combined blades are composed of several outer blades, middle blades and inner blades. In the cutting process, each cutting blade only bears about 1 / 3 of the workload, and there is also a cutting knife on the inner side of each cutting blade. Therefore, chip can be removed smoothly.

In addition, due to the characteristic that each cutting blade bears a part of cutting work respectively, it is extremely difficult for the drilling hole to generate edge collapse. Hollow drill bits are classified into high speed steel drill bits, hard alloy drill bits and tungsten steel drill bits. Effective cutting depth: 35mm, 50mm, 100mm, 120mm, 150mm, 300mm；Borehole diameter specification: 12mm to 160mm; The main materials of drill bits are high speed steel, powder metallurgy and hard alloy.

It is suitable for electric motors such as magnetic drill / magnetic seat drill / drilling machine / lathe. Its complete in types and specifications are suitable for various brands of imported magnetic seat drill and magnetic drill. Straight handles are suitable for various domestic magnetic drill and general drilling machine, vertical bench drill, boring machine, machine tool, etc. Each drill bit can drill 1,000 - 3,000 holes. This product is used together with magnetic drill, and the drilling efficiency is 8 - 10 times that of common drill bits.

Each hollow drill bit can drill 1,000 - 3,000 holes. For example, it only takes 25 - 40 seconds to drill holes with a steel plate thickness of 30mm and diameter of 40mm, which greatly improves the working efficiency and saves a lot of labor and material resources. It is especially welcomed and used by steel structure engineering, shipbuilding industry, railway construction, mold manufacturing industry, papermaking industry, bridges, bridge equipment installation, large-scale equipment maintenance, power plant maintenance and all pipeline engineering.