Hey UltraPeepi,
in case a spindle doesn’t turn on, if its VFD is correctly wired with a safety circuit, it has already signaled this error condition to the CNC controller which stops the program then. To check if the VFD itself is operating, it can be set to send acknowledgement signals via ModBus, or one of its logic output terminals can be programmed to one of the functions that confirms its operation and this can be wired to the safety circuit as above. In both cases the CNC controller would be signaled the error condition and stop or not even start the program.
As for the closed loop stepper, this is a stepper motor that has a so-called encoder sitting on the rear of its shaft which is a glass disc with a system of scales etched into it that are sensed by a infrared photoelectric sensor and which can hereby be used to track every step and direction of the motor’s movement. The closed-loop stepper driver compares the given step commands and the executed ones and can signal a error condition if the motor did not follow the steps. A small deviation, in case of staying behind an amount of steps, can be corrected by the motor if it is not blocked, but if it lost too many steps or if it cannot execute the step commands anymore, it signals an error and the program is aborted.
The use of motors with encoders brings the benefit to be able to identify an operating condition that causes steps to be lost, e.g. when the feed rate is too high. By avoiding conditions where the stepper driver signals errors, the operator is able to prevent programming the machine in a way that the machine is not able to cope with the mechanical load and also that the tool is in danger to be broken during operation. But it is not able to detect a tool breakage during operation.
A tool breakage detection system is not part of the Elite Series. You find this on rather expensive industrial milling centers, however it is imaginable to retrofit such a system. There exist different methods to realize tool breakage detection, from simplest to most expensive:
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Tool length verification.
With this method, you set up a tool table with the tool lengths as usual, but at positions in the program flow, you check if the tool length is still the same as registered. You need the tool length probe and a custom script to achieve this functionality.
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Whisker wand switch
On automatic tool change, an actuator with a whisker wand detects if the tool is there. Saves time compared to 1.
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Light reflection system
The tool is exposed to light. Electronics determine whether the tool is present by analysing the reflective light pattern from the rotating tool.
On very expensive machines, a laser measurement can also be used to measure the exact diameter and thus the wear of the tool, which can then be calculated into the milling path.
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Smart tool monitoring system
The machine data are analyzed to determine tool condition and wear with different methods which also allow to predict tool breakage in the future. Example