Question about Loc-tite

[Metal Butcher]

I have been using Red color Stud locker #7331 with out any problems.

I occasionally use green color #609, the only problem is its very short cure time that requires pressing the parts together without any interruption.

I heard or read somewhere that when similar metals are joined a primer should be used. I have never used Loc-tite on similar metals in the past.

Do both of the above products require a primer when used between two aluminum parts?

Will a regular red or gray lacquer primer do the trick?

Anyone have any experience bonding aluminum to aluminum?

-MB

 

[Mainer]

I don't think the issue is similar metals, it's the type of metal. As far as I know, aluminum doesn't need a primer, but you can get the definitive word at www.loctite.com .

 

[DICKEYBIRD]

The primer they're referring to is a Loctite brand spray-on cleaner solvent called Locquic that degreases the parts and leaves a film of chemical that speeds the cure and strengthens the bond.

A lacquer primer would totally screw up the Loctite chemistry.

Google Loquic primer & look around for a .pdf spec sheet. All you'll ever need to know about Loctite primers...good stuff!

 

[BobWarfield]

I've used LocTite to bond aluminum to aluminum as an aid to fixturing for my CNC work:

That's two MIC6 cast tool and jig plates, 1/4" thick, LocTited together and then clamped for extra measure. The LocTite holds pretty well!

I wouldn't call it structural by any means, but it was very convenient as I cut all the way around the perimeter of parts to keep them stuck to the bottom plate so they didn't fly around the shop and annoy the wife by forcing her to take me to the emergency room.

Cheers,

BW

 

[Metal Butcher]

Thanks to ALL for your replies. And thanks Bob Warfield for answering my question with a photo and first hand experience. That was very helpful. You also answered a nagging set up question in the back of my mind on how to hold a workpiece and mill around it in one set up. :big:

-MB

 

[kvom]

Somewhat OT, but I saw in one of the MIT milliung videos where flat pieces too wide for the vise jaws were held to the top surface of the vise with 2-sided tape. It seems to be very strong vs. shearing force. I would guess from that video that Bob could have joined the two plates with tape as well, and possibly easier than with Loc-tite.

 

[BobWarfield]

You can use double sided tape, and Superglue also works. Loctite is what I have in the shop and it doesn't get any easier.

Both Loctite and Superglue will release with heat (about 400 degrees F I believe), but the fumes are nasty: use adequate ventilation.

Lastly, you can pop a part loose while end milling if too much force is used. I managed to do that on one of the 3 I machined. I reduced the depths of cut for the last little bit to reduce cutting force.

There are a lot of other tactics. You can leave "tabs" in place very easily if you are CNC'ing and snip them with a wire cutters, file the excess, and that works. I have also seen (but not tried) leaving a very thin "foil" layer and then knocking the part out with a mallet to break the foil. You can use Dop Wax to hold a part, and then place the fixture on a hot plate to melt the wax. And of course there are low temp tooling allows that are about the same result.

In the end, Loctite was handy though!

Cheers,

BW

 

[Metal Butcher]

Very good information that will help me in the future! :bow:

Thanks Bob! Thanks Kvom!

-MB

 

[Maryak]

Back in the "Dark Ages" - Newspaper and wood working glue, (Aquadhere), were used to secure an oversize part directly to the table. The newspaper was soaked in the glue and paced between the part and the table. I've tried it and it works. The downside is cleaning both the part and the table of the paper/glue combo.

Best Regards
Bob

 

[BobWarfield]

I have heard hot glue works well too, and that it will just pop off the metal without a residue. It is more suitable for edges than sandwiches though.

I can't remember where I first heard of using LocTite like glue, but I use it that way for a lot more than just fasteners. For example, securing dowel pins in their holes and similar shaft to bore applications work well too.

Cheers,

BW

 

[Captain Jerry]

A caution about using loc-tite or other types of adhesive to stick two aluminum plates together if you plan to drill through both pieces. The little bit of metal deformation at the bottom of the top plate as the drill breaks through acts like a wedge and puts the bond in tension rather than shear. It tries to lift top piece off of the bottom piece. I have done it that way when there was no other way and get away with it about half the time. One or two holes, maybe. More than that is risky. My solution has been to drill two holes. Seperate the parts and clean them. Chamfer or debur the holes and reglue. Then drill two more holes.

I guess if the total glued surface is large compared to the number of holes it might not be a problem. I was drilling five 1/4" holes through plates with a total mating surface of 4 sq.in.

Best to all
Jerry

 

[shred]

I've used carpet tape and superglue to hold pieces down. Superglue is the one I prefer. You have to keep the parts cool via coolant of some sort or the glue will come loose however (the same is true of tape... get it hot enough and it comes loose, but it also doesn't much like coolant)