Hello,
I searched and searched and couldn’t find the answer to what I’m looking. I want to glue a few bolts to the underside of my cf part made from epoxy resin. It’s a vent piece for my car, therefore non-structural and only exposed to rain, snow etc. What’s the simplest way of doing this? Urethane adhesive? Or just more epoxy resin will do?
Regards
Carlo
Don’t just glue the fasteners directly with no support. Glue them down and then add composite patches around them to lock them in place. If you make the patches round then they’ll even look good. Make sure to use peel ply or roughen up the surface where the patch will cold bond.
What kind of glue should I use?
Research/Google for easy 2-part epoxies that match the heat and strength that your part requires. There is a myriad of them so don’t over think them or get lost.
Perhaps a quick check on ebay will get you a good price and a not so out of expiration date item.
In the beginning days of development…I used to grind down the heads of stainless bolts until the head was thin with a 40* grit abrasive and also roughen up the composite area where it would be attached.
Next up, mix the epoxy adhesive and drop a glob in the center of the mount point. I would then slowly lower and spin the bolt head into the epoxy fully emerging it.
My framing jigs which would temporarily hold my bolts was made of coat hangers pre-bent and pre-bolted so I only had to lower the whole thing into place and press down…spinning w=each bolt head once seated.
If you add the composite patches you can get away with just using epoxy under the head since the patch is what is holding it in place. Good idea to grind the head down thinner or use a fastener that already has a large flat head. Google “big head fasteners” or “bonded fasteners” or use something like a “large diameter flush head bolt” from McMaster.
Otherwise if you need to use a thick headed bolt then pot the head in a structural adhesive like Hysol or Scotch Weld before you apply the patch over the top. The idea is to prevent rotation and to fillet the thick head to allow the patch to bond properly.
bonded fasteners - http://www.rotaloc.com/products/bonding_fasteners.html
Permabond 2 part - http://www.permabond.com/product/two-part_epoxies.html
I just like to mix up a slurry of epoxy and cotton flock. Then I cover the flat surface of the bolt or the weld on attachment. I cover it with carbon if it is for aesthetics.
Are cotton flock and micro fibres ( http://www.ecfibreglasssupplies.co.uk/p-589-west-system-403-microfibres.aspx) the same thing?
How does epoxy plus micro fibres compare with a structural adhesive?
Clickbond is another one, where you glue the fastener on, not IN the composite.
3M has a host of bonding resins. I’ve used Clickbonds onto metal plates using 3M 8115 panel adhesive. TL;CT (too long, can’t tell), we used it for quick heating, and my god that stuff was strong!!!
Most methacrylates will work (Plexus, Lord, 3M, Hysol, etc.)
The fasteners: www.bighead.co.uk, www.rotaloc.com, www.weldmount.com
If it is a non structural piece, an MS Polymer would also work.
Cotton flock is just really finely chopped cotton. When mixed thick it becomes a thixotropic paste (very slow moving/sagging paste), and it is intended for strengthening of structural joints. Microspheres or micro balloons are just that, microscopic glass balls. They act like balls. They will roll around on each other. It’s harder to keep that mixture together in one area. They are best used for filling holes and sanding/fairing.
instead of using this type of fasteners wouldn’t be easier to use rivet nut ?
i’m an inexperienced first timer, going to make a car hood (bonnet) from cf and epoxy…
what adhesive should i use to bond the metal hardware to the composite? some type of structural epoxy?
what adhesive should i use to bond the two sides of my cf hood together? a structural polyurethane?
it’s mind-boggling, how many choices of adhesives there are
i was looking at permabond adhesives, but i’m in USA. any certain products you guys always go to?
this picture is the fastening hardware im trying to bond to the hood
