In reply to Gordon Stainforth:
> Not quite sure why they have to be very sharp at all.
They aren't sharp. But they are shaped.
The most important property of TC in this application is its hardness; the resistance to being worn down.
It was a pretty poor pun... And my reply was really addressing your first, bold, statement that TC is not used in pole tips.
You leave the engineering to the engineers, and we'll leave the dodgy puns to the wordsmiths.