Loctite Troubles

[coogfan]

Hi Everybody,

I have an application where I am having severe issues with Loctite either setting up to quickly or not at all. I am threading a peek (Victrex 450G) "plug" into a metal shell (4130 alloy w/ QPQ/Nitrided surface treatment) and using Loctite 272 to bond these two pieces. I am slo spraying the peek with Loctite 7642 primer. The thread is 1.875-12UN and approx 2 inches long.

I am required to thread the peek in to a given distance and either face issues with the Loctite activating prior to achieving this distance, or it not "curing" at all. For the assemblies that did not cure, I've had some success with heating them in an oven at 200F for 20 mins, but can't explain why this works or doesn't.

Does anyone have any tips or ticks to help with this, or is it just the nature of the beast? We are working on a number of ways to retain mechanically, but for now I'm curious about the Loctite. Thanks in advance!

 

[tbuelna]

Here's what the datasheet for Loctite 272 says, "This product is not normally recommended for use on plastics (particularly thermoplastic materials where stress cracking of the plastic could result). Users are recommended to confirm compatibility of the product with such substrates." It's an anaerobic compound, so naturally it is very sensitive to mating surface conditions, bond line gap, surface cleanliness, etc.

 

[EdStainless]

You need to ask Loctite for the correct formulation to use.
Little things, such as surface cleanliness (and cleaner residue) along with additives in the PEEK will have major impact.

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P.E. Metallurgy, Plymouth Tube