Spring washer OR removing a bolt? 1

[scotsguy]

Could you please look at the picture attached and tell what, in your opinion would/could cause this.The picture shows the pad at the end of a mounting arm. There are actually 2, one either side each has 2 bolt holes. These pads are bolted onto a piece of kit known as a turnaround. The turnaround unit weighs approx .25 tonne,and has the chain/grippers that carry newspapers rattling through it at upto 70,000 copies per hour. Though the picture shows a normal 8.8 hex headed mild steel bolt,cap bolts are also used. I need to know what caused the burr and the indent ring around the hole?Kindest regards.

 

[desertfox]

Hi scotsguy

All I can see is the hole, I can see no bolt or even a hint of a spring washer.
Regarding the hole it looks very much like it is fitted with a helicoil insert which is being extracted in which case it as to be the bolt trying to extract it.
Can you tell us more about how the bolts,the joint construction and how they might be loaded by the device you call a turn around ie are they in shear. tension , bending etc.
Did the bolts fail? how long have the bolts been in service?
If you can post a picture of the rest of the machine we might be able to help further.

desertfox

 

[Strong]

I agree that when you zoom in on image it looks like a Helicoil that is starting to pull out. The burr is a pealed back thread and the ring around the hole is the Helicoil insert.

Walt

 

[1gibson]

Looks like a thru hole to me, and it looks like the other part's holes don't line up exactly. And/or the weight of the component was hanging on the bolt as it was threaded/unthreaded?

The bolt attempted to tap the thru hole during removal/install for whatever reason.

Is the 'ring' on the surface approximately the same diameter as the cap screw used?