brightspark
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- yarm stockton on tees
any sharp edge on material is a weak point for shear. a rounded edge isn't
Fast typing finger eh Dan.
Rolled thread is stronger as it’s cold forged in essence so the grain structure is correctIn answer to your thread title. Tensile strength is based on the material not any physical attribute of the fixing in question. So mild steel has a lower tensile strength than en8 etc.
A fine pitch bolt of the same material as a coarse pitch bolt will have a greater pull out strength and a greater shear strength than the coarse pitch due to the core size being bigger and there being more thread contact than the coarse.
The angle is exactly the same in all metric threads so not sure where that's come from? It's always 60°
As above a rolled thread is stronger than a cut thread but by how much I'm not sure, I'd say because it's more uniform with less stress risers from burrs etc.
If the coarse thread is what screws into the casting perhaps the different pitches are to make sure eits screwed in the right way? Are the threads different lengths?
Rolled thread is stronger as it’s cold forged in essence so the grain structure is correct
Potential for a stress raiser on a properly formed cut thread is at the finish of the cut.
Material tensile strength doesn’t always equate to stronger in service. A pal made some studs for his race bike in en24 and the failed due to stress raisers at thread end so he made some more from en8 and they were successful
Very true 12.9 don’t like shock treatment but under controlled load the only grade that could survive my pressbrake tooling clampsA case of a lot stronger was worse than a bit stronger. Speccing the correct grade bolt or fixing is often overlooked. People just stick a 12.9 in thinking its better than an 8.8 where an 8.8 would be fine, 12.9 might be too stiff if say a bit of flex is required at the joint.
I can’t quite remember but truck fifth wheel fixing bolts are higher tensile than8.8
Yes they are , 10.9 usually m16Could be 10.9
The weight carrying should be mostly borne by the friction between the two mating surfaces not on the studs. It's only completely dependent on the studs if they are not tightened up.
Not as simple as that, surface finish is also criticalany sharp edge on material is a weak point for shear. a rounded edge isn't
you could go on forever. even slight scratches on critical components can severely weaken them that's why polished is one of the best finishes
yes only using beads it peenes the surface and relieves the stressI have a (hazy) recollection that a quick dose of the sandblaster applied to the area where the cut thread ends is an effective way to stress relieve the interface. A sort of micro-peening, if you will. Does that make any sense?