Metal ring in centre of cutting discs-what is it`s function?

[mart]

What is the function/purpose of the metal ring around the centre of the hole in a cutting disc (115mmx1.1mm disc in this case)?

I ask this because I have had one come off the 2nd disc I used in a new batch that I purchased recently. I am hoping the other discs are ok-it could be a “one off”. I would have thought that the metal ring is to provide support at the point where the grinder “nut” holds it, but discs tend to have the ring on one side only, ie what supports the edge of the other side of the disc?

 

[KENB]

the ring is to stop any play in the disk as cetrafuglr force will explode it if you have more than a 1/4 mm play. plus it stops you clapming the nut down to tight and cracking said disk.
i drilled out some old 100mm ones once for my 4 inch grinder. still picking bits out of my arm. lol

 

[Hitch]

To make a precise mounting. 22.2mm iirc.

 

[Arsonista]

Check the others WELL. If they let go it causes pain.