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Rotary broaching is a metalworking technique used to cut shapes like hexagons and squares, both internally and externally. In this process, a technician mounts a cutting head into a tool holder and advances it into a component like a bolt to cut it. The tool holder rotates, allowing the cutting head to dig in and produce the desired shape. A wide assortment of symmetrical shapes can be cut into various metals using this technique, which can work extremely quickly to allow for high volume parts production.
This metalworking process is sometimes known as wobble broaching. This refers to the fact that because the tool head is placed at a slight angle, the work appears to wobble during cutting. The angle allows the cutting head to place pressure on only part of the component being worked at any given time. This allows the rotary broaching equipment to cut each side of the shape individually for high precision and reliability.
Rotary broaching can be performed by hand, or with specialized equipment. Computer numerical control systems allow operators to program in settings for mass production of identical parts. The technician determines what needs to be cut and how many components should be included, and sets the device to cut bolts and other products on an assembly line. Computers can control each step of the rotary broaching process for entirely automated production, with periodic quality control checks to make sure the equipment functions correctly.
Facilities can use other broaching techniques as well. The best option depends on the pieces being worked and the type of metal involved. Softer metals tend to be more appropriate for broaching, as they are less likely to chip or clog the cutting head as it moves through the materials. Lubrication must be provided throughout the cutting process to reduce friction, prevent overheating, and trap shavings and shards so they do not escape into the work area, where they might cause injuries or damage equipment.
Costs for a rotary broaching system can depend on the size and capacity. It may be possible to rent or lease equipment if a metalworking facility does not want to buy it. Companies with limited broaching needs may contract out the work to other facilities, as they may be able to perform it in the most cost effective way and with the greatest precision due to their extensive experience. This method allows for very exact screw heads, internal threads, and other cuts to metal pieces.