Bolting
Bolting
(OP)
Just wanted to know what are the considerations in changing from a regular head bolt to a C'sk head bolt in terms of the stress it can withstand & hence induced load. I am having to consider a C'sk due to reduced head height, and are using the same thread ( M8).
Thanks
Clive
Thanks
Clive





RE: Bolting
Regards,
Cory
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips Fora.
RE: Bolting
Thanks
Clive
RE: Bolting
Regards,
Cory
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips Fora.
RE: Bolting
8 or 9 and use the standard clamping force. I do not think he is talking about socket head bolts in a counterbored hole. I thought c'sunk heads were only good
for small clamping forces.
RE: Bolting
RE: Bolting
If they are going into tapped holes in the mating part then that alignment is an issue. Increasing the csk will allow the heads to lie flush but doesn't solve the stress issue.
KENAT, probably the least qualified checker you'll ever meet...
RE: Bolting
RE: Bolting
Unless proven by testing, I do not use a flush head design in a structural application that will demand full strength from the part.
RE: Bolting
KENAT, probably the least qualified checker you'll ever meet...
RE: Bolting
I have now found out that the particular "taptite" fastener only comes in 8.8 quality. The bolts are bolting a steel ring to an aluminium substrate. Previously bolts were 10.9. I assume I am going to reduce my clamping load due to the lower toque I can apply to this bolt.
RE: Bolting
Taptites are also available in an alloy steel version which will meet PC10.9 strength levels. This is a through hardened version that is designed just for tapping into aluminum.
I would consider that the likely failure mode of this assembly is going to be head failure of the bolt at a level below the theoretical max level that the bolt shank is capable of. Ask your fastener vendor if this is a head critical design.
RE: Bolting
If you know of anyone, I would be extremely grateful if you could let me know a contact.
Thanks
RE: Bolting
RE: Bolting
http://camcar.smartcats.com/default.asp
RE: Bolting
Doesn't a bolt head fail due to the stress concentration at the transition from the shank to the head? If this is the case, then isn't it logical that a CS bolt would hold more load as the stress concentration factor is directly related to the radius of the transition. Smaller the radius = grater stress concentration factor. Because a CS does not have a full 90 at the transition I would think it's radius would be greater and therefore have a lower stress concentration factor to handle more load.
my $.02
RE: Bolting
Thanks again
RE: Bolting
The issue with recessed heads is failure from the underhead radius into the recess, as a result of having either a large and/or deep recess in the head of the part. You end up on flush head parts with a catch 22 for high load applications where either you put in a nice big recess to generate plenty of torque and clamp (and then the head breaks off), or you make the recess small and you get a nice strong part (but you can't apply enough torque get it tight enough to generate much clamp without the recess failing). It turns out to be a compromise as to what your end goal is for the joint. FLush heads are always fun!
RE: Bolting
Thanks in advance
cpercival
RE: Bolting
Regards,
Cory
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips Fora.
RE: Bolting
counterbore allows a "real" hex or socket head.
Flat head screws of equal grade accept about 40% less torque and clamping than SHCS.
compare PDF document page 90 and 93 here. (Page 83 and 86 catalog page numbers)
htt