illustration below shows a typical control panel for a CNC machining center. Turning center control panel will be almost identical. The letter -M in the model identification stands for Milling - a CNC turning center (lathe) will have the letter -T instead (for Turning).
Although the control panel layout and its features will vary from one manufacturer to another and even from one control model to another for the same manufacturer, there are enough similarities to group them and examine each group.
The control system has its own independent power source, therefore it has its own ON-OFF buttons. Even if the CNC machine itself is turned on, it does not mean its control system is under power as well. However, the machine power has to be turned on before the control system can be turned on via Control Panel. The main reason is to separate mechanical, pneumatic and hydraulic elements from the electronic elements.
The OFF button of the Control Panel is usually the first one to use when the machine is powered down. Usually, the Power-Off order is the opposite of the Power-On order. As the exact procedures will vary from machine to machine, always consult the manufacturer’s recommendations and procedures.
The largest area of the Control Panel is the display screen - the monitor of the whole control system.
There are three main elements:
▪Display area
▪Arrow soft keys
▪Selection soft keys
When the power is supplied to the control panel, the display shows its default screen. In order to navigate between many screen pages, the control system offers several soft keys, located just below the display screen (five keys shown in the illustration + two for navigation).
In order to avoid hundreds of buttons and a very large control panel, modern control systems only display features directly related to some main selection group. For example, if you choose the POS selection key, the screen will show only those features that are related to various positions - such as absolute, relative, machine, distance-to-go, etc.
Soft keys always work in conjunction with Selection Keys (described next). The illustration shows the meaning of soft keys when the Offset/Setting selection key is pressed.
Incidently, the meaning of the word soft-key is not related to its physical composition or the feel of one’s finger when the key is pressed. The word ‘soft’ is just a short form of ‘software’ - as in ‘software keys’. The implication is that it is the software of the control system that determines the meaning of each soft key, based on the selection key. That is the main reason why the soft keys are not identified in any way.
Navigation Keys
Regardless of the number of actual soft keys, there are also two arrow keys - one to the left and one to the right of the actual soft keys:
| ▪LEFT arrow key | ... Function Menu selection |
| ▪RIGHT arrow key | ... Operation Menu selection |
In conjunction with each other, these two arrow keys are used to navigate different pages and sub pages of the screen display.
As mentioned in the previous section, the actual functionality of each soft-key is always directly dependent on the currently active Selection Key. In other words, the selection shown on the screen above each soft key will be different for each selection key. The illustration below shows the most common key selections available:
POS Key
POS indicates settings related to various position displays. This is probably the most commonly screen used in part setup. The main modes that can be used are:
| ▪ABS | ... Absolute display |
| ▪REL | ... Relative display |
| ▪ALL | ... All displays |
| ▪MACH | ... Machine position display |
The two main displays - ABS and REL - are used the most. The absolute display is normally used during program processing - it shows the current tool position based on part zero location. The relative display is used mainly during setup, for activities such as setting work offset, tool length offset, and others. In this case, at a certain critical position (commonly at machine zero), the CNC operator sets the relative display to zero and makes the required offset measurement, for example, sets G54 work offset or G43 H.. tool length offset.
Both ABS and REL displays are usually shown in larger form than normally, so they can be seen from a distance during part setup.
MACH selection key shows the current tool position always measured from the machine zero (home position). This display is totally independent from any offset setting or part program data.
If you want to see both ABS and REL position displays, and MACH display as well, on the same screen, just press the ALL selection key. The display of each part is smaller, but all important data is shown on a single screen. In addition to the four modes, the control system also shows some current activities from the part program, such as current spindle speed, cutting feedrate, active program codes, etc.
PROG Key
PROG indicates the program mode. The contents of the screen - what you can actually do - depends on the selection of control mode, located on the operation panel of the control (described in the next chapter):
