An area of machine tool usage very often overlooked is the ordering or sequence of tools within the machine, whether in the toolchanger on a CNC mill, or their respective positions in the turret of a lathe. This may not seem important, but it is a subject worthy of consideration.
Firstly, when changing over from one program to the next, do you need to remove all the tools each time, or can a few be left ‘permanently’ setup in the machine saving on tool setting time, therefore avoiding the need to search for that elusive collet that someone else is using? Secondly, are you achieving the best cycle time, or is the machine waiting for the right tool to get to position? Thirdly, are there certain tools in the turret, which might present a collision problem if selected in the wrong order?
Haas lathes provide the user with the ability to determine the method of selecting a tool by either commanding a specific direction (CW or CCW), or allowing the machine to make the decision and take the Shortest route. Setting 97 Tool Change Direction is a standard feature on all Haas turning centres and determines the default tool change direction. It may be set to either Shortest, or M17/M18.
When “Shortest” is selected, the control will turn the direction necessary to reach the next tool with the least movement. The program can still use M17 and M18 to fix the tool change direction, but once this is done it is not possible to revert back to the shortest tool direction other than Reset or M30/M02.
Selecting M17/M18, the control will move the tool turret either always forward, or always reverse, based on the most recent M17 or M18. When Reset, Power On, or M30/M02 is executed, the control will assume M17 as the tool turret direction during tool changes, always forward. This option is useful when a program must avoid certain areas of the tool turret due to odd-sized tools.