Thread: Heat proof glue

Hi all,
I need to find a suitable glue to glue magnets into slots and fill the slots. I have tried epoxy which works nicely but with the item in use it gets warm and the epoxy starts to stink.

Any suggestions?

Oh, and when i say "heat" i'm talking no more than 150 probably even less.

Ew

Silicone compound ("RTV") is sticky and heat resistant, but maybe not rigid enough for this job?

Jordan

Ueee,

You could try a polyurethane glue.

Have a read of this as is says it will tollerate high temps.

http://home.howstuffworks.com/uses-f...-adhesives.htm

I've used PU glue to very successfully hold REMs in place in timber, but no idea about the heat aspects. Just have to be mindful about the glue expanding and pushing the magnet out of place but in your application I doubt that would be a problem (coz the REM will stick like the proverbial to the steel)

Originally Posted by FenceFurniture

I've used PU glue to very successfully hold REMs in place in timber, but no idea about the heat aspects. Just have to be mindful about the glue expanding and pushing the magnet out of place but in your application I doubt that would be a problem (coz the REM will stick like the proverbial to the steel)

FF,

That's what I figured.

what about a JB weld type of product devcon or one of those .

johno

Originally Posted by Ueee

Hi all,
I need to find a suitable glue to glue magnets into slots and fill the slots. I have tried epoxy which works nicely but with the item in use it gets warm and the epoxy starts to stink.

Any suggestions?

Oh, and when i say "heat" i'm talking no more than 150 probably even less.

Ew

I think that epoxy resin was and is the right choice. However, there are many many very different epoxies. And some do indeed smell much more than others.

As first measure, I would try to cure the glued item in an oven, up to 150C should be fine for most epoxies. Do this once it has initially hardened, as most epoxy glues produce their own heat during curing, and that may lead to overheating and breakdown when added to the heat in the oven.

If that does not help, you may look at some epoxies said to have reduced allergic reaction in people. Safe-t-poxy comes to mind but things may have changed in the past 20 years. A friend of mine was building his own aircraft (a vari Eze) in the garage and after a while he was so sensitized, that even years later he always got a bad rash on his hands just from smelling minute amounts of epoxy. Unfortunately, safe epoxies do cost more. There are also epoxies optimised for high temperatures, but as always as soon as you want/need something specialized prices skyrocket.

By the way, with some epoxies you can control hardness by modifying the binder/hardener ratio (more hardener meaning you get a softer and less brittle end product, yes it is contra intuitive).

Hi,

Loctite 670 or 870 (I can't remember what the number is) is a heat resistant thread glue. May work in your situation. I'll find a bottle tomorrow and have a look.

Ben.

Have a look in the Sika flex site .
I was there one day looking for something else and they had some products
to do with sealing and heat.There maybe what you want in there.
Grahame

G'day Ewan,
I'm nut sure what your application is or how much time you want to spend on it but one option is to mill your slots oversize in the width then use a soft metal to hammer caulk the magnets in place.
As mentioned earlier, the magnets will more or less hold them selves in the slots, you just need to stop them from moving around too much.
Copper would be more durable but aluminium is probably easier to work.
You will also end up with a pretty inlay like finish too.
Cheers,
Greg.

Originally Posted by kwijibo99

...use a soft metal to hammer caulk the magnets in place.

Surely there'd be too much risk of snapping the very brittle magnets? I've known them to chip just by their own force snapping together.

Most run-of-the-mill epoxies are only good to about 100C.

JB Weld is good to 290 degrees C and would be my recommendation.

Thanks guys,
The item is a permanent magnet chuck, it needs to be steel for longevity and the slots need to be filled so it can be wiped clean and steel dust doesn't gather in the slots.
The JB weld sounds like it will do the trick, i am also casting some hard polyurethane rubber at the moment and might try it.

Cheers,
Ew

Originally Posted by Ueee

Thanks guys,
The item is a permanent magnet chuck, it needs to be steel for longevity and the slots need to be filled so it can be wiped clean and steel dust doesn't gather in the slots.
The JB weld sounds like it will do the trick, i am also casting some hard polyurethane rubber at the moment and might try it.

Cheers,
Ew

Hi Ew,

Could you not machine so that the magnets are flush with the surface and then fill the gaps with soft solder. Also would a 10 thou mylar film over the top prevent metal dust getting into any crevices. This could be sacrificial and easily replaced.

Originally Posted by Ueee

Thanks guys,
The item is a permanent magnet chuck, it needs to be steel for longevity and the slots need to be filled so it can be wiped clean and steel dust doesn't gather in the slots.
The JB weld sounds like it will do the trick, i am also casting some hard polyurethane rubber at the moment and might try it.

Cheers,
Ew

Hello Ew,

Could you provide a bit more information about the castable hard rubber? I'm toying with the idea of a DIY plug and socket for the Isoma as an alternative to the underwhelming quality of the cheap sockets I thought I could use.

As a kid I used Devcon aluminium putty to build up a damaged area of a magnesium KTM crankcase. It stayed put and coped with the heat. The stuff is machinable.

The JB Weld does sound promising though.

BT