CNC Control Setup for Milling and Turning:. Peter Smid
switches (toggle or button type)
▪Rotary switches
▪Edit key
▪Emergency Stop switch
▪Setup handle
In general, the main purpose of the Control Panel is to provide the software aspects of operating a CNC machine, while the Operation Panel provides the hardware aspects. Both of these two portions of a CNC system are related and interfaced at the manufacturing stage. They always work together.
There are many different versions of machine operation panels. They vary in features and layout, some use toggle switches, others use push-buttons. Some controls use symbolic descriptions, others use literal descriptions. Regardless of these differences, overwhelming majority of features is common to all control systems. Features that are less common often reflect a special option, unique to a particular machine tool builder.
Modern CNC systems use pictorial symbols rather than words (literal descriptions). The most common pictorial symbols will be shown later in this chapter. On the previous page is a schematic layout of a typical operation panel using literal descriptions for easier orientation. Although the shown layout is only a composite based on several operation panels, it does represent all major features found on any modern CNC control system. Not all features can be shown here, for example those relating to ATC (Automatic Tool Changer) or APC (Automatic Pallet Changer). Also, features that are particular to a specific CNC machine cannot be shown either. As always, it is important to consult all manuals that are supplied with the CNC machine. They are always based on the actual machine model and its control system. Various manuals provided to the user list in detail all functions available and describe how they work.
When viewing a machine Operation Panel, its layout is composed of light indicators and various switches and buttons. Needless to say, all CNC operators should be thoroughly familiar will all features of both the Control Panel and the Operation Panel. Many operator related features are also directly related to part programming, so it is equally important that CNC programmers have a good (or even better) knowledge of the machine/control operating features.
From all different buttons located on the CNC machine Operation Panel, there are two main buttons that are somewhat more important than others, although all are equally important.
Power ON / Ready Light Indicator
As the button label Power ON suggests, this is the main power switch (button) for the machine as well as control system. When the machine power is supplied, the control does not get power automatically right away, the power has to be turned on in subsequent steps.
It is not unusual to perform three or even four steps to get all power needed before using the CNC machine - for example:
▪Main switch (breaker) on the wall - ON
▪Machine main power switch - ON
▪Control ON - first time to power electronics
▪Control ON - second time to power hydraulics
Power-Off procedure is usually the reverse order of the Power-On procedure. As various CNC machines vary quite a bit in the way they are powered, the actual procedure may also vary quite a bit, so always consult machine tool manual first.
Check CNC machine manual for exact Power ON/OFF procedure
When all power has been supplied, the Ready light turns on, to indicate machine is ready for initial setup, including power supply to the control unit, as described in the previous chapter.
Cycle Start / Feedhold - Auto Operation
Another push button that belongs to the main category Auto, contains the key Cycle Start button - typically a push-button with a light that is built-into the switch or provided above it. The words ‘cycle start’ simply mean that a series of events will take place when this button is pressed. Typically, there are three main events activated by Cycle Start (others are also available):
▪Part program processing in continuous mode
▪Part program processing in single block mode
▪MDI commands operation
The other button in the same Auto category is the Feedhold button, usually located next to the Cycle Start button. It can only be used when the part program is running (being processed or executed). Its sole purpose is to stop all axis motion. Feedhold is particularly useful during part setup, often used to determine critical clearances in tight spots. Even during actual machining - and if used properly - feedhold button can be very handy for removing chips, adjusting coolant nozzles, and other last-minute adjustments.
The CNC system along with the CNC machine can perform many operations, often in a very short time. Many activities come and go and it would be very difficult to see what state the control system is at any given moment without special indicator lights.
Even the Power On, Ready, Cycle Start and Feedhold buttons are lighted when in effect. However, many additional indicator lights are used during program processing - they indicate the current control status.
Indicator Lights - Three Groups
Most control systems include a series of small light indicators that will often vary in color (green or amber), but will share one common feature - they cannot be changed. These lights are called the status indicators (or just status lights). Their purpose is to convey a simple and quick visual message to the CNC operator. For example, a red indicator light will relate to a trouble of some kind, such as low level of machine slide lubricator or a general system or program fault (alarm). An amber light (amber is a shade of orange) will typically identify a warning, but it could also identify a certain condition. A green indicator light identifies a ‘go’ or ‘ready’ condition - when everything is in order.
Every Operation Panel contains a number of indicator lights - those are lights that indicate a particular control status at any given time. These lights use colors to suggest their importance - typical colors are:
| RED | Indicates a severe condition, such as alarm or fault -always pay attention to this problem |
| AMBER | Indicates a standard condition; a certain status confirmation - usually presents no emergency |