You will understand that I can't be specific in this case, but with the very high spindle speeds of which these machines are capable I can say that the potential exists for failures far beyond the capacity of
2.5mm of steel to stop. And you mustn't forget the sight windows. Acrylic hasn't got a show of stopping a high energy projectile. The windows have to be polycarbonate even if the degradation caused by cutting fluids means they have to be replaced every few years.Eric Stevens
Eric,
First I'd like to thank you for a fascinating thread. My sympathy goes out to the victim and his family.
Everyone seems to have focused on bad code. What if the spindle for some freak reason went to an un commanded rpm? Memory or component failure could cause such a situation.
If the potential exists to punch though 2.5 mm of metal then the MTB should use thicker metal. I've had to hammer out doors on cnc's from stock leaving a chuck from cracked inserts, inserting casting for wrong part that looks about the same size, program error, ect.
All of our machines have automatic door closers so door weight isn't an issue.
As far as the windows go. you stack up layers, put in guard bars or put in a camera system. Windows don't last forever. On machines that don't have crashes, the flow of chips erode the glass to the point you can't see in there at all and the glass / acrylic sandwich has to be replaced.
Our Multiplex's don't get a year out of windows due to chips flying at them.
The bottom line is that guarding should protect the operator from a 'chit happens' day. You can not for see everything.
Wes S
To: Eric Stevens,
There are CNC Parameters that control whether the macro variables are cleared at reset (#100 series, and separate #500 series) If the original problem was related to clearing the variables , have you considered setting these parameters to prevent that?
Also, Would your programs accept a parameter limitation for the rotational speed of the boring bar?. If this is a common bar I would think a limiting absolute value could be installed in the parameters that would prevent overspeeding of the tool regardless of the program source.
I wish you luck...
Eric Stevens wrote:
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