Secondary bonding for automotive parts (epoxy? polyurethane?)

General Composites Discussions Composites Talk
#1

I have a construction question many of you likely have experience in. I’ve made hoods and other parts in the past with these two methods:

  1. infused the skin, put the core on top and did a regular wet-bag layup…not the best method and its not

  2. Infused the top skin, infused the bottom skin, and ‘glued’ them together by using a filled mix of the infusion resin. While I haven’t had any failures with this yet, the infusion resin is NOT an adhesive.

Here’s the question:
If I’m secondary bonding a hood skin with a lower skeleton (or if i’m bonding wing skins to one another and the spars), what is the adhesive of choice? Should I use a polyurethane adhesive like Permabond or one of the Hysol epoxies? Any recommendations?

#2

For aerospace I’ve always used bonding epoxies. There are a variety from Henkel. You can mix in beads to insure bond gap is within specifications. A proper bond will fail in the interlaminar bonds of the carbon/glass. I’ve also bonded things together using straight resin like you mentioned. Not the best but does work to a point. For structural parts I’d only use a proper bonding adhesive. Like bonding skins to a spar or what not.

#3

Thanks Sammy. Any particular henkel/hysol product you recommend? Does it typically come in tube form or cans?

#4

Araldite 2015 is my choice of structural epoxy adhesive. I actually prefer a methyl methacrylate adhesive like SAF or Plexus for composite to composite bonding, they are hard to beat. Plexus is ludicrously expensive though.

For composite to metal bonding, Araldite 2015 is wonderful. 2014 is also good, but I prefer the flex of 2015.

#5

Jeeez, these all are expensive. $20 for 50mL. How long of a bead can i make with 50mL?

#6

If you can get your hands on Gurit Spabond340LV in pails, this works very well for bonding, and price is much better than tubes. In general, any adhesive you buy, its always more cost efficient to buy by the pail and hand mix it.

#7

I’d also recommend the Proset thickened epoxies. the 175/276 is a good one and if I remember correctly it already has bond line spacers in it. I think it runs about $40-$60 depending on your source for a 400ml tube. It’s easier to get then the Spabond in the states and uses a common two part construction gun for dispensing.

#8

http://www.merrittsupply.com/category/338-pro-set.aspx

#9

In the US you can get Spabond (epoxy) and Crestabond (MMA) quite good. Both work perfekt. The Crestabond is little more flexible and less sensitive id surface preparation. For a Hood I would prefer the Crestabond.

#10

When is it better to use MMA instead of epoxy, or vice versa? From what I have found out they can be comparable, but I’ve so far not found any info suggesting one is better in certain circumstances.

#11

I have a small shop at home where I fix racing cars and my go to resin is a local So. CA company PTM&W (I use there stuff for all my infusions). I called Scot the tech rep and he asked a lot of questions about my application,

I ordered PTM&W 6271 and I have not looked back.
It comes in A&B 1 qt. each 50/50 under $100 shipped next day.

my application gluing strakes back on a GTLM 488 Ferrari and fixing PWC cars.

Today I am working on Giancarlo Fisichella’s car

#12

I’ve been using 3m dp125 gray and it seems to be working fine. I’d like to compare it to aradlite 2015 or something else though. I’m bonding aluminum to epoxy/carbon

#13

PTM&W has a new adhesive on the shelf for co bonding dissimilar material. more info call Scot (@ PTM&W) tell him I mention it. he is the guy that does the R&D for certs.

#14

Very nice Tom. Those strakes are just edge bonded? The original epoxy joints failed? Is there a trick to making these stronger so they don’t fail?

#15

Does aluminum need to be treated with anything before bonding?

#16

the strakes are bonded with the 6271 and I put 1 ply doubler on the outside

#17

Tom what’s going on with the step in the diffuser? Is it vented as a double diffuser, or is it really a blockage and a 2 tier arrangement?

Sent from my A0001 using Tapatalk

#18

no clue, it’s a Ferrari thing