No Sue, it's not a sign of weakness. I would use your school's discipline strategy as an effective way of dealing with unacceptable behaviour, if you were asked about discipline issues at interview. Can you think of other methods you've seen which work or fail? I believe it's experience which you gather as you go along.
It's not a sign of weakness at all, Sue. You work in a collegiate system with a clear hierarchy - use it. In fact, I've always found that children see not sending them out as a sign of weakness: they assume you want to "hide" your problems, and take advantage of the fact that you're not confident enough to involve your PT when they know that they've done something that warrants PT involvement.Of course, though, you have a wide range of in-class sanctions which will be described in your discipline policy, and you should only send pupils out of the room when (a) you've exhausted those possibilities, or (b) they've done something so serious it merits immediate withdrawal.Follow the policy and no one can blame you.