By Aiden ArmstrongOne service common to most machine shops is drilling. A form of cutting, a drilling operation involves the execution of a hole in solid material by rotating a drill bit at up to several thousand of revolutions per minute. The circular action produces a circular cross-section cut in the workpiece. The size of the hole will vary according to specifications and the size of the drill bit.
Twist Drills
Drills come in many types or classes. Some are more popular to use than others are. Among the many types, the most important is the twist drill.
The most important type of drill is the twist drill or bit. It derives its name from the spiral flutes that run along most of its length. These flutes may number anywhere from two to four. A two-flute drill is for an actual straight drilling operation while three and four-flute drills are employed to actually enlarge holes already cast or punch.
Its design and materials construction gives the operator the ability to slice through various materials including:
Concrete
Metal
Plastic
Wood
Machinists recognize and select the right twist drill by considering the following factors:
Shank style: This is either straight or taper
Length: The length of a twist bit falls into one of these 3 categories:
Screw Machine
Jobber
Taper
Material: M2 high-speed steel for general purpose metal cutting; cobalt for longer tool (drill) life and carbide where issues focus on feed, speed, and rigidity
Flute Type: Helical points or Spiral
Smart machinists use such criteria to help them make the best selection possible.
Twist Drills and the Drilling Operation
Drilling a hole to meet the specifications demanded by a customer necessitates employing the right tool. Fortunately, there are options. However, for many machinists, the best drill bit is a twist drill. Its ability to drill cleanly and effectively through a variety of material makes it ideal for a straightforward drilling operation.
