Threadlocker for stainlees steel
Threadlocker for stainlees steel
(OP)
I am trying to lock two mating 316 stainless steel threaded (5/16-32) parts together permanently. I need them to hold 100 in-lb breakaway torque after curing. I have tried both Loctite 262 and 2760 and the breakaway torque is only around 50 in-lb. Any suggestions? I was going to try some 3M structural adhesive (epoxy) next.





RE: Threadlocker for stainlees steel
RE: Threadlocker for stainlees steel
I am satisified with Loctite 242 for stainless steel screws, but I have never tried to measure the break-away torque. We do want to be able to remove our screws.
I have used Loctite RC635. According to Loctite literature, stainless steel is an "inactive" material, and it requires primer. RC635 with primer is practically impossible to take apart. I suggest you read up on this. The primer might work for the 262 as well.
RE: Threadlocker for stainlees steel
http://tds.loctite.com/tds5/docs/2760-EN.pdf
Is a datasheet for one of your threadlockers. In there, a 3/8 steel bolt is shown to have a breakaway torque of only 70 in-lb. after full cure, and stainless fasteners are listed as obtaining only about 25-50% of the strength of plain steel fasteners. The other compound,
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does a little bit better...but note the cure speed for stainless steel fasteners.
You could try higher-strength anaerobic adhesives (Loctite 277 is one), and use the primer/activators listed on the datasheets for those, and wait the prescribed cure time before testing...
RE: Threadlocker for stainlees steel
RE: Threadlocker for stainlees steel
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RE: Threadlocker for stainlees steel
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You may also want to try pre-applied thread adhesive rather than the hand applied stuff. Here is a link:
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RE: Threadlocker for stainlees steel
Agreed. Bolts are not a preferred method of making permanent connections. Rivets, welds, brazes, and adhesive bonds are generally more suited to permanent attachments.
If the design drives you to a bolted connection, you could always lock-weld the head of the bolt. However, you have to be careful not to put to much heat into the bolt such that you lose your preload.
I'm surprised you were able to remove the bolts with Loctite 2760 (strong stuff). I'd talk to the Loctite rep or try Loctite 266 or 277. You'll also want to be sure that the threads and the hole are both clean before installation. If not, you won't get the bond you're looking for.
As mentioned above, 300 series stainless threaded into to itself is notorious for galling up. I'm surprised that you're able to take it apart to begin with. Maybe the Loctite is preventing galling?
RE: Threadlocker for stainlees steel