Epoxy bonding

[kozak]

I did a quick search before typing this and i didn;t find much in the way of results. our team is thinking of bonding some of our intake manifold (aluminum) or all of it we haven;t decided yet. any way i just wanted to get an idea of the types of epoxy everyone is using and the prep work everyone is doing on the surfaces. i know that 3M makes a good one i looked at the data sheet, and locktite makes one but i couldn't find any info on it.

[pengulns2001]

if your bonding Al to Al just weld it and save yourself the hasle

[Matt Gignac]

Might not always be the best idea to weld aluminum. You'll kill the temper and bring it back to T0 condition, with much lower strength values. So in some cases it may be better to bond.

Matt Gignac
McGill Racing Team

[pengulns2001]

somehow i dont think an intake is one of those cases

[Blake_DFSAE]

if you weld aluminum it requires heat treatment to maintain the mech. properties

[pengulns2001]

we are all talking about intakes here right? are you planning on running 2000psi or something that might cause Al welds to explode? probably not, just weld it you will have so many less headaches

[mark zhai]

thin AL hard to weld. will warp, burn. heavy AL easy to weld, but defeats purpose of a lightweight intake.

[DaveC]

Good aluminum welds look impressive...

[pengulns2001]

get it welded by someone else... i can weld 0.35 and i am by no means a good welder

[kozak]

welding is not the point here. and btw .35 is not thin. i want to try to bond, it is 100 times easier and much faster. and looking at 3M epoxy when done right can have a shear strength of 1600-2800 psi.

[pengulns2001]

it doesnt get much thinner than .028 so i would say .035 is pretty thin... but thats not the point, epoxy can be a problem especially with fuel even though you make think the fuel will never get up sometimes fumes are enough to weaken epoxy so you have to take that into consideration. i have had bad luck with epoxy on intakes in the past in a backfire situation and i dont think its worth the risk

[Travis Garrison]

Plus aluminum welds are going to leak...more air, more HP http://fsae.com/groupee_common/emoticons/icon_wink.gif

[LSU Dave]

Originally posted by Travis Garrison:
Plus aluminum welds are going to leak...more air, more HP http://fsae.com/groupee_common/emoticons/icon_wink.gif

My gosh?!? What are you talking about? No one has ever had a leaking intake manifold!

[deersound]

get it welded by someone else... i can weld 0.35 and i am by no means a good welder

I assume penguin meant 0.035, not 0.35. By the way, 0.035 and 0.028 are standard steel sizes, but aluminum usually comes in 0.032, 0.030, 0.025, or 0.040. An average TIG welder should be able to weld 0.035 steel without much difficulty (as long as he/she's not filling big gaps). That same welder will have a much more difficult time with aluminum.

Additionally, welding 0.032" aluminum will absolutely cause it to warp, and warp substantially. For an intake, this is probably undesireable.

Adhesives aren't a bad way to go as long as you design your joints to have large shear areas.

Kozak, for bonding to steel and aluminum we generally have used a fine-grit sandblast followed by an acetone wipedown. Using a neutralizer after the acetone might improve that process a bit, but we haven't had problems with it. If the metal is too thin to sandblast, we'll scrub at it with scotchbright or foam sanding blocks instead.

For epoxy we've found a strong and durable (yet inexpensive) Hysol formulation that we like. In the past we've used 3M's DP-460, but that stuff is more expensive than drugs and doesn't give you long to work with. We only have used these as structural adhesives for use at room-ish temperatures, so we don't know anything about their chemical or temperature resistances. A quick call to Loctite or 3M will solve that problem for you.

Lastly, if you're really worried about temperature or chemical resistances, you might want to look into metal-filled epoxies.

I also know there's an ASTM procedure we use for the surface treatment of metals prior to adhesive bonding. I can't remember it off the top of my head, but a quick Google search should find it for you.

[pengulns2001]

i of course meant .035 but i didnt know that Al would be .032 i just really look at it and assume its 035 049 etc by recognition from steel still 032 Al isnt all that hard and im not a trained welder or anything

[KU_Racing]

At a previous co-op job we used Hysol for al-al bonding in vehicle frames- it is amazingly strong and durable stuff, highly vibration and chemical resistant. I would definately recommend it for bonding your intake.

[Korey Morris]

We used 3M's DP-460 for some fairly critical parts on the UK Solar Car. It has an all aluminum chassis, and we don't have a facility on campus to heat treat it after welding, so once the initial round of welding was done, any addition that had to be added (most notably the throttle and brake pedals and all electronic mounts and brackets). This passed scrutineering at the American Solar Challenge, but only by a hair.

Anyway, after seeing it in action on the solar car in a critical role, I'd trust it on my car's intake.

[Didier Beaudoin]

I've already had a bad experience with a bonded intake.

Here's my advice: Make absolutely sure the epoxy you use resists to fuel!! Also, if you plan on using an air filter that requires oil on it, make sure it dries completely before you put it on, or else the oil can react with the bonding! This is the last thing you want to happen at the competition, you can beleive me.

[pengulns2001]

... not that it matters but our Al shit is definatly .035 it says .035WALL right on the side

[mark zhai]

hysol loctite aerospace epoxy. forgot the numbers (actually too lazy to go down to the shop and look them up). but the aerospace shit runs like $100 per 50cc tube, we got a nice sponsorship and it works good. fyi - 2800 shear strength is optimal bonding chara, ie perfect surfaces, temp, bead size, etc. you change anything and the 2800 becomes like 200 psi. if u dont believe me - then try it and test it yourself.

[Steve Yao]

Would there be an issue with applying a internal sealing coat, like on fuel tanks?


Originally posted by Didier Beaudoin:
I've already had a bad experience with a bonded intake.

Here's my advice: Make absolutely sure the epoxy you use resists to fuel!! Also, if you plan on using an air filter that requires oil on it, make sure it dries completely before you put it on, or else the oil can react with the bonding! This is the last thing you want to happen at the competition, you can beleive me.

[BStoney]

Be careful using too thin of aluminum on your intake plenum. Without proper internal supports and thick enough sheet, when the engine is running the whole plenum will pulse (expand and contract) like squeezing a rubber balloon. This is bad news for fatigue life on your joints!!! I am not an engine guy at all, but I can only imagine unpredictable variable plenum volume is bad news?!?

I know we have seen this before optimizing our design, as well as other teams running similar manifolds...I think the fellas from UTA can vouch for this as well...