1. Both cemented carbide twist drills and metal drills can drill iron, but cemented carbide twist drills can not drill special metals such as white steel.

2. Metal drills are usually made of alloy steel. Drillable special metal materials are the most widely used.

3. The handle of cemented carbide twist drill has two forms: one is clamped in the drill chuck while the other is inserted in the cone of the spindle or tailstock.

4. The drill handle of cemented carbide bit is medium carbon steel, and the head is inlaid with cemented carbide for cutting.

5. Cemented carbide twist drills with welded blades or crowns are suitable for processing cast iron, hardened steel and non-metallic materials, and integral cemented carbide twist drills are used for processing instrument parts and printed circuit boards.