Aluminium Bonding

If I understand you correctly, it sounds as though the autoclave process is causing a vacuum to form. If so, put some random cuts in the contacting surfaces so that a vacuum cannot form.

Hope this helps!

What is the tolerance between the mail and female parts? are they binding as in large peg in small hole? If so ream out the female part. If the contact surface is sticking, do you have contamination that is causing them to be baked together?

There is no build up on the pin or docking position. Hadn't thought about vacuum. It is a positive pressure autoclave. Could vacuum be an issue. There is some evidence of corrosion, is there a coating I could apply to the pin or docking position that might alleviate??

A sketch of the configuration and materials would be helpful. Lacking that information, I suggest venting the pin or the socket to prevent vacuum forces, coating the pin or the socket with some non-stick material (teflon perhaps), or changing the material to something that won't corrode in the autoclave.

Heating of course would expand any air in between the 2 pieces then cooling would cause a vacuum to occur. as someone already mentioned. Also if the male and female are to close in size .. metal expands when heated and could be causing the male to get stuck in the female ................. sounds like fun .... err wait ...uhhmmm. Like i was saying heat -stuck ...... try cutting a slot in the pin deep enough to get below the area were the female point stops ... or drill a hole through the female from the bottom of the hole to the outside of the block (on a diagonal). One of those will take care of it if its a vacuum and can be reasonable done. If its a fit-up problem . Drill or ream out the female with the appropriate size bit or tooling.

What are tolerances for pin/machined out cavity?

What is grade of Aluminum?

What is maximum temperature of autoclave?

What is geometry of pins- round, sharp corners etc.

What finish iif any to the trays?

Why aluminum and not stainless?

milo

Is this how it looks (or close to it)?

I think there's some confusion as to what's sticking. Is it the trays or the pins? Your post, however, definitely mentioned that it's the trays. If so, I'd have to go with the vacuum theory. The illustration doesn't show that the trays are pressed together tightly (I can make a better illustration but I'm a bit lazy today) but, in your case, I think they are.

One suggestion I can give is to find some way to put some space in between each tray if modifying the trays is out of the question.

A picture is worth a thousand words.

This is a very good sketch of the setup

The white pin is sticking in the socket of the green tray i.e. the green is the tray

The contact is surface to surface

What do you think>>

Increase the hole size or decrease the pin diameter slightly, then round the end of the pin.

Is the auotclave pressurized then reduced back to atmospheric? As it cools down there may be a vacuum formed.