Commonly used materials for drill bits are low carbon steel, high carbon steel, high-speed steel, cobalt steel, tungsten carbide, polycrystalline diamond, etc. Surface coatings are black oxide, titanium nitride, titanium aluminum nitride, titanium carbonitride, and diamond powder.
Machining drills can be divided into two categories, one is a flat drill, a twist drill, a center drill, a deep hole drill, and other drilling tools, and the other is reaming drill, countersinking drill, and other reaming drills. Auger bits are used for construction projects with an outer diameter of 400-600 mm and a length of 12-8 meters. Use a flat-bottom drill bit for loose soil layers, a rake head for mixed fill layers, and a bucket for obstacles such as concrete and strips. Type drill.
Twist drills are currently the most productive. It includes a cutting point at the tip of a cylindrical shaft with a helical groove. The groove adopts a helical mechanism, and the chips are removed from the hole by rotating the helical surface around the rotation axis. Torque bits range from 0.002 to 3.5 inches in diameter and 25.5 inches in length.
Step drills are tapered drills with a stepped profile. The drill bit can drill the full range of holes needed in the tabletop to speed up the installation of fixtures. The transition between each diameter is straight to create a countersink. The advantage of this style is that both diameters have the same flute characteristics, preventing the drill from clogging when drilling in softer materials such as aluminum; by contrast, drills with slide-in collars do not have the same the benefits of. Most of these bits are customized for each application, which makes them more expensive.
Step drills are most commonly used on softer materials such as plywood, particleboard, drywall, acrylic, and laminate; they can also be used on very thin sheet metal, but sheet metal often causes the drill to wear and dull prematurely.