An insert bit is a removable work piece common in all manner of manufacturing tools. These bits are common in everything from hand-held screwdrivers all the way up to complex machine lathes. An insert bit has several advantages over non-removable bits, most of which come down to money. They are easy to maintain, allow a single tool to have multiple functions and require less expensive materials. The large number of advantages and few disadvantages have made these bits common in a huge range of applications.
The most common type of insert bit an average person will encounter is in a screw driver or electric drill. Bits of this type are small metal pieces that fit into a cavity on the tool. This allows the same tool to fit multiple screw sizes or drill different holes in different materials. While these are a very simple form of insert bit, they illustrate the ease of use and versatility that have made this technology so common.
In an industrial setting, the insert bits are generally larger and more complex, but they are the same as the household versions. These bits can be a small cutting or drilling surface, similar to their more common cousins, or they can be a large blade or milling head. In either case, the insert bit is connected to a larger machine.
The reason for these interchangeable bits comes down to money. The biggest factor is in the cost of replacing the bit itself. When an insert bit wears out, the bit is discarded and a new one is put on the machine. If the bit were part of the work head, the entire assembly would need to be replaced. By limiting the wear to the small object, the cost of replacement is a fraction of what it could be.
Since the insert bit is designed to come separate from the machine, the same machine can provide different functions by simply changing the bit. This is the same principle as the home screwdriver, just on a much larger scale. Rather than cutting down the number of cheap hand tools, these insert bits eliminate very expensive manufacturing systems.
One additional factor that plays into the system that is easy to miss is the material the bit is made of. In order to work a material, the bit needs to be harder than the substance being worked. If the bit is softer, or even equal, the material will deform rather than properly shape. Since the bits may be removed from the machine, it is possible to have very high-quality bits connected to a lower-quality work arm.