Need plastic or epoxy help

[originator]

Hello, I am looking for some advice with gluing some metal together with a black epoxy or plastic that will sand nicely, and support heat to 300 degrees in an anodizing vat.

I have a product that requires several pieces of small machined aluminum rectangles to be assembled together with .05 space between them (space is to appear as black glue). The complete surface of all assembled parts is sanded while held together with a jig. The entire thing is then anodized, so it ends up as one very smooth surface and visually appealing. I have been using a product called potting epoxy, which is more of a rubbery feeling product at first, but gets pretty hard after a few days. The back of all the parts are routed out to form a cavity where the glue will run through the the design, creating a support structure to hold the parts together. The rear side of the panel looks like a 4" x 6" rectangle filled with a black epoxy designf illing most of the center. The aluminum is 1/4 inch thick material, and I am routing down .15 for the glue strutcure layer, then sanding the back side to smooth out the glue that may extrude out of the cavity.

I need a product in black that can substitute for the potting epoxy, that could have a very short curing time so that the jigs can be freed up as quickly as possible. This potting epoxy label says 48 hours at 68F, or 1 hour at 150, but since it has a tape covering it to hold the glue in and not drip out, I can't put it in an oven.

Please let me know if there is a good option to sub out the glue I am using that is taking to long to dry.

Thanks

 

[patprimmer]

Have you tried google. If you do that first it saves us the trouble of doing it for you.

There are epoxies designed for repairing cast iron pipe that stand high temps. These are used by plumbers and may be obtainable from plumbers supplies.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[berkshire]

originator (Industrial)
Most epoxys that are colored black, simply have carbon black added as a pigment. I would suggest you find an epoxy that does what you want, then color it to suit your needs.
B.E.

 

[originator]

I have been trying experiments with various epoxies, and under heat in the anodizing process, the part has been bending slightly without the use of a jig attached. Using a jig means creating the same number of jigs for each part sent to the anodizer, plus the anodizer has to take it off to sand the back, then replace it before anodizing, so it is a lot of work and extra cost to go that route. I am hoping to find an epozy or other material that will not warp at 200-300 degrees F. I will see about finding a high temp epoxy mentioned earlier. Presumably that should do the job.

 

[btrueblood]

Why can't you cure at 150 F? If the tape you are using can't take that temperature (pretty wimpy tape if you ask me , then use a tape that can take it. 3M blue masking tape is rated to stand 30 min. at 200 F, I'd sure give it a go. On the same page as the blue masking tape, McMaster lists a high-temp. polyester tape that can stand 425 deg. F with no adhesive residue, and an EPDM tape (EPDM will stand up to darn near any aqeuous solution) rated to 250 F. You can also search for plater's tape, and Kapton (polyimide film) tapes. If 'twere me, I'd take a trip to the local hardware store (or surf on over to McMaster.com), and buy a roll of each type of tape on the shelf, then come home, slap some tape on a piece of scrap, and bake the mess in a 150 oven for an hour. Pick the best one...

 

[metron]

Loctite make a ceramic epoxy called Fixmaster Nordbak Brushable ceramic, good for temps to 288 degrees C.
Warning though it is around $500.00 Australian for a 500ml tin.
Here is the link to the product,

http://www.loctite.com.au/int_henkel/loctite_au/index.cfm?&pageid=133&layout=2

 

[boldfish]

Look into Stycast 2651.
This is a resin used in a two part application that may perform to your requirements depending on the hardener used.
It's been awhile since I have used this epoxy but from what I remember, it performed well in a very similar situation.

 

[originator]

Thanks guys I'll read up on those products. The 2 part epoxy I am using is not working out as expected, it stays somewhat flexible when it is cured, it is a thermal potting epoxy, so it really isn't designed for a robust hold.

The epoxy has to be carefully poured into a mold and cleanup is very time consuming when it gets on the jig. I am looking to design a programmable CNC system to dispense the glue into the areas precisely to avoid contact with the surounding areas and to keep it consistent and neat. Ideally a one part would be great that could stay in the dispensing tube/syringe until needed again, simply cap it off, but I don't know of such a product that could stay liquid for long periods of time. Maybe just mix the 2 parts, then quickly put it in the pumping system and run a batch, clean it out and start over

I did solve the heat issue by using hot air on the whole thing for an hour and that worked great to get it cured fast some blue 3m painting tape.