[Tolyatti]

Can anyone tell me if there's any provision in a Fanuc 10M control to incorporate a safety interlock which will prevent Cycle Start from occurring unless a user-added switch is closed? The issue is an older cnc machine that never had doors or any kind of enclosure. We're trying to make the machine safer by installing a mechanical barrier between the operator and the spindle, and having the barrier actuate a switch when correctly in position. Any help would be much appreciated.

[Al_The_Man]

You could intercept the E-stop input into the controller, there is a dedicated input for it, you would have to consult the input listing sheet.
Al.

[Tolyatti]

Would this put the machine into the same state as if one had pressed e-stop?

[Al_The_Man]

Depending on how the ladder is written, it may just e_stop the controller itself.
Al.

[fordav11]

there is provision. interlocks were added to an old machine with a 10T at my work recently

[Al_The_Man]

there is provision. interlocks were added to an old machine with a 10T at my work recently

Did they update the documentation? If so the specific input they used would indicate as to whether it is a mod originally allowed for or a new input?
Al.

[underthetire]

We put safety mats down, but had Uptime re-write the ladder to accommodate it.

[fordav11]

they (our maintenance people and a Fanuc tech) never update anything.
its all top secret

[Tolyatti]

My personal inclination is to sell the machine-a 1987 Enshu, complete with its barely readable documentation. Failing that, next best bet is probably to install a light curtain and have it trigger "reset" which would stop the spindle and the servos. Several months ago, someone reached in and tried to adjust the coolant hose while the machine was running. The outcome was unfortunate, but predictable.

[Dan Fritz]

It might be best to use the "Feed Hold" signal. That signal is normally closed, so a completed circuit takes the control OUT of feed hold. When the feed hold signal is open, any motion is stopped, and any subsequent cycle start input is ignored. Feed hold will not drop out the servos, so you won't lose axis position or reset the program. If feed hold opens while in the middle of a cycle, then you close the circuit again, you can just cycle start to resume the program. Depending on how the ladder is written, it may not turn off the spindle, however.

You could just wire an external normally closed switch in series with the one on the operator's panel. Both switches will have to be closed in order to run. The signal "latches" internally, so a momentary break in the signal will put the control into feed hold until you cycle start again. Just closing the circuit will not make the machine "take off"

There are also interlock signals for each axis, so a separate signal could be used for X, Y , and Z. Those signals just stop axis motion though.

Try to decide just what you want to happen when the safety barricade is actuated. An E-stop would drop off the servos and (in older controls) will lose axis position also. E-stop will stop the splindle and everything else as well. Feed hold lets you resume a cycle gracefully.

[underthetire]

You can also see if the control has an external reset input. We use that for safety interlocks a lot. Stops everything without killing the servos.

[Tolyatti]

What we need to have happen is an immediate spindle-off and the servos stopped when the curtain is triggered. We can intercept cycle-start, but interrupting a cnc machine while it's doing something is not so simple. E-stop would be the most inconvenient way to do it. Triggering reset is undesirable also as it resets the program to the beginning, and would be an extreme nuisance while trying to edit, set offsets etc, if the light beam were to be interrrupted and causing resets. So the reset command could only be active when the spindle is turning, and i don't have enough knowledge, nor the means of getting it on this 25 yo machine. I like Dan Fritz's Feed Hold idea the best IF we can figure out how to stop the spindle also, as it's the spindle that's the real source of danger.
Underthetire, I don't know if the machine has an external reset input. There are a couple of dummy plugs on Amphenol-type connectors on the panel, but the manual is written in Japanese with hand written notes in something resembling English, so the wiring is a mystery. The age of the machine and the arcane electrical diagrams are working against us. Thanks for the responses, i appreciate the ideas.

[Dan Fritz]

The external reset signal (ERS) and the E-stop signal will both reset the program to the begining, making the resumption of the program a real problem. The Feed Hold signal will make the servos decellerate to a stop, but will not stop the spindle unless it's coded in the ladder. To my knowledge, there is no Fanuc-supplied input signal that will stop the servos, stop the spindle, and NOT reset the program.

If someone can modify the ladder for you, you could just tie the Feed Hold input to whatever output enables your spindle (or) you can designate a new input signal that will put the CNC into feed hold AND stop the spindle. It's do-able, but you will need to edit the ladder to do that.

[Al_The_Man]

The input units have a couple of terminals marked 'Safety Door' but IIRC they are in the E-Stop circuit, but if you have to go that route, it may be a convenient place to tie into.
Al.

[Tolyatti]

Well, this may have become moot as an outside consultant is citing OSHA reg 1910.217 which, as far as I have found relates to punch presses, not CNCs. But at any rate the regulation states "The safety distance (D(s)) from the sensing field to the point of operation shall be greater than the distance determined by the following formula:

D(s) = 63 inches/second X T(s)
where:

D(s) = minimum safety distance (inches); 63 inches/second = hand speed constant;
and

T(s) = stopping time of the press measured at approximately 90 deg. position of crankshaft rotation (seconds). "

So, applying this to a CNC machine, and I'm not convinced that it does apply, if it takes one second for the spindle to stop, then the light curtain would have to be 63 inches away from the spindle, which is unworkable. We're probably headed back to the idea of a mechanical barrier. Again, thanks to all for the input.