A few months ago I was running test programs generated by a new CAM system we are working on. Our target CNC machine is a 3-axis desktop mill: the Emco F1, with a 0.7 horsepower motor. Shown below:
To help avoid machine crashes I added a final check before emitting G-code. The system would run a simulation of the G-code, calculate the average material removal rate (in cubic inches per minute) and warn me if it was excessive.
We were cutting 6061 aluminum and I wanted to be extremely conservative since our machine is so wimpy, so I set the system to warn me about anything above 0.6 cubic inches per minute.
After a few very conservative part programs went through the simulator without incident I made some changes to the toolpath generation system to speed things up.
The first G-code program I generated with the new system caused a warning, but in a rush I ignored it, thinking it was probably not too bad. As soon as the program reached the toolpath that produced the warning it crashed.
Below is a histogram showing the MRR for each operation I ran on the mill up to and including the crashing operation (on the far right):
It's a bad idea to ignore warnings!