Spinning roll material

I don't quite get the picture.

As i see it you have 2 kg of yarn rolled onto a 3" pipe with wall thickens of 2mm

This seems to fit over a shaft to keep it in position.

The yarn is used at 20km/h.

The problem might be that the rotational speed increases as the roll becomes smaller.

No mention is made of bearings, metal on metal is assumed.

It seems to be the pipe that goes.

Consider using:

A bigger pipe. A softer material. Bearings.

I think your problem is you need a bigger/stronger shaft and better bearings. I am basing it on a small water wheel ( 5" diameter carbon steel x 18" wide 480 lbs. app.)I made for a customer a few years back that the shaft (2" solid carbon steel 30" span between pillow block bearings) failed. it seems the guy didn't grease the bearings regular and the dryer they got the worse the wheel would run till finally the bearing failed and the shaft bent/broke. I would have never thought my common since engineering to be faulty on this one till I had a buddy at the paper mill run some calcs. on the whole set-up. The bearings made all the difference.

pipewelder

Thank you for your suggest, I will add this information, the pipe joinning with plastic for connection with bearing, this failure cause from bearing only or plastic material too