Automatic tool changer
For all but the simplest of parts, CNC machine tools use a wide range of cutting tools, which must be inserted into the machine’s spindle in a preset sequence as specified by the part program. This can be carried out manually, but most modern machines are fitted with a tool magazine and automatic tool changer mechanism to allow the correct tool to be called up and inserted into the machine spindle automatically. On the latest machining centres a tool can be removed and a new one inserted in just over 1½ seconds, so maximizingthe time that the machine is actually cutting metal. Magazines in the form of an endless belt with up to 240 tool stations are available. They offer adequate capacity to cover all tooling needs for a number of different jobs, plus a number of sister tools forthe most frequently used ones, but manually locating the correct tool at the instant required is not practicable with tool stores of any significant size and can only be managed efficiently by an MCU. The MCU can conveniently combine this control activity with automatic tool life monitoring (Waters F., Fundamentals of Manufacturing for Engineers, p. 260).
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