▪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 |
| GREEN | Indicates a favorable condition, such as ‘good’, ‘setting OK’ or ‘ready to go’ |
The three common control status indicator lights can be grouped by their actual purpose:
▪Zero return position
▪Cycle end
▪Errors / Alarms / Faults
Additional lights may indicate status that is unique to a particular CNC machine tool.
Zero Return
When one or more machine axis reaches the machine zero reference position (home position), a status indicator light on the Operation Panel will turn on, as a confirmation. Each axis has its own light, so it is easy to check if all axes have reached the machine zero.
These lights are usually green, but can be amber as well - they are assigned to each available axis the machine tool has. On the most common 3-axis CNC vertical machines, there will be three lights identified by the machine axis letters X-Y-Z. If the fourth axis is also present on the machine, the corresponding light can be identified by the digit 4 (as for ‘fourth axis’), as ‘4th’, or it can be the exact name of the fourth axis, such as A or B. Typically it is the A-axis for CNC vertical machining centers and the B-axis for CNC horizontal machining centers.
Most CNC machines have to be zeroed (homed) in ALL axes before running a part program
Cycle End
The end of a cycle can be only temporary (using M00 and M01) or permanent (M02 or M30). Fanuc and similar control systems have at least three confirmation lights that relate to Cycle End modes:
| M00 | Indicator light turns ON, if Program Stop M00 has been detected in the CNC program |
| M01 | Indicator light turns ON, if Optional ProgramStop M01 has been detected in the CNCprogram |
| M02 | Indicator light turn ON, if Program End M02 has been detected in the CNC program (obsolete) |
| M30 |
Indicator light
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