Is calf crank a deadly move???

I've been practicing BJJ for almost 2 yrs now and I got promoted to blue belt recently.
In our gym we're not free to use techniques like knee bar, calf crank, and lots of other foot locks while practicing in our gi. But we're free to use almost all of the techniques that I mentioned above during the no gi training time except for techniques like twister and heel hook.
So I prefer to use calf crank often because I don't really want to hurt my opponent by using knee bar or other dangerous foot locks.
Last night, my instructor told me not to use calf crank often because it causes much pain to my opponent.
I just couldn't help thinking why I should stop using calf crank...
Is calf crank a deadly move???

Hi Jasonic.
It's not a deadly move but can be devastating to your opponents leg. It's painful. What you move be able to do is just touch and go. Or let your opponent work out of it while you bait him to the next trap. The point is, you shouldn't need to hurt your opponent in any submission. The longer they are around, the longer you'll have a good partner. Keep em around if you can.

There are no confirmed deaths via calf crank. However many, many taps.

with straight arm bars and knee bars you pretty much know when to tap. an arm crush or caf crush feels like you can fight it off longer than you think you can. youll try to defend it too long and blow out the elbow or knee