New adhesives - are they as good/better than welding?

[BoatBuilderDave]

Doesn't mean that gluing is better/ stronger than welding. Just means that on this case the roll cage met the standards and the chap had no problems.

Likewise Lotus versus Renault which is not a fair comparison as Lotus have been making composite and fibreglass cars with gluing for years. I still don't accept that a glue joint can be better, stronger than a welded joint.

You can easily make a well designed adhesive joint which will not break before the metal. At that point it no longer matters how strong it is.

From then on you only care about longevity.

A weld introduces a Heat Affected Zone around the weld. So while the weld may be strong, the metal around is is weakened somewhat. Adhesives do not introduce any such HAZ.

It's unlikely that an adhesive based butt joint would be anywhere near as strong as a welded butt joint, but then, who would create such a joint?

A welded lap may be weaker than a glued lap due to the HAZ. Particularly for thin metal.

Most of what I know about glues is from building wooden boats, but the principles remain the same.

I still don't think it's going to replace welding wholesale, but as has been pointed out, it's been used in aircraft for a long time - thin sheets, easy to have lap joints in the design. No distortion from heating.

Horses for courses.

 

[seriesonewelder]

Got to disagree there.
A chap at the Northern Off Road Club, had a two wheel drive Cosworth powered buggy. The roll cage / space frame was glued together not welded. It of course had to pass MSA testing to the same standards as a welded cage. He raced it for years without problems.

I can remember reading about a chap who turned up with a roll cage with glued joints at an off road comp. safari. The scrutineer hit one of the tubes with a sledge hammer to test it - the tube fell off.

 

[Robotstar5]

I can remember reading about a chap who turned up with a roll cage with glued joints at an off road comp. safari. The scrutineer hit one of the tubes with a sledge hammer to test it - the tube fell off.

need a youtube clip!

 

[BoatBuilderDave]

I can remember reading about a chap who turned up with a roll cage with glued joints at an off road comp. safari. The scrutineer hit one of the tubes with a sledge hammer to test it - the tube fell off.

Fair enough, but I broke apart my first weld joints with my bare hands (after they cooled )

Just cause you have found an example of someone who has done it wrong does not mean it cannot be done right.

 

[madkayaker]

im fairly sure glue is not an mot approved means of repair unless it is on a like for like basis.

 

[seriesonewelder]

Fair enough, but I broke apart my first weld joints with my bare hands (after they cooled )

Just cause you have found an example of someone who has done it wrong does not mean it cannot be done right.

I have also flown transcontinental and watched the wing tips of the plane move up and down an alarming distance - I have yet to witness a glued wing fail ~ hope I never do, however if I do I'll report back here.

 

[brightspark]

I have also flown transcontinental and watched the wing tips of the plane move up and down an alarming distance - I have yet to witness a glued wing fail ~ hope I never do, however if I do I'll report back here.

if the wings didnt flex they would snap .it would be the same with high rise flats and towers made of steel

 

[PhillipM]

WRT the norc racer, I've heard of one that had a semi-monocoque that was glued together with a welded roll cage inside it. But as far as I know nobody has a bonded roll cage, there's not enough surface area and the MSA has no way of know that every joint is sound.

 

[pedrobedro]

Glued joints are done on big flat areas. I've never seen a glue that will hold in an application like a fillet weld or a tube welded end on to another tube for a wishbone or a plate welded to an axle for a trailing arm bracket as is used in my type of construction scenario. That would be something I can do in a freezing cold shed for a reasonable price and expect it to stay together.

 

[chunkolini]

Off topic O know.
But I remember the Mz Scorpion, I had always ridden singles and fell in love with that bike. Never bought one. Maybe one of these days.
Yes I know there is one on fleabay.

 

[pedrobedro]

Off topic O know.
But I remember the Mz Scorpion, I had always ridden singles and fell in love with that bike. Never bought one. Maybe one of these days.
Yes I know there is one on fleabay.

One sold round at the shop a month ago, it went for around £1000. The engine is Yamaha XT660 single with 5 valve head. The MT-03 uses a similar engine now and looks good but it's not glued together.

Fair enough, but I broke apart my first weld joints with my bare hands (after they cooled )

That doesn't mean glue is stronger than weld, it just means your weld was not very good

 

[outofthefire]

Doesn't mean that gluing is better/ stronger than welding. Just means that on this case the roll cage met the standards and the chap had no problems.

Likewise Lotus versus Renault which is not a fair comparison as Lotus have been making composite and fibreglass cars with gluing for years. I still don't accept that a glue joint can be better, stronger than a welded joint.

Bud do you think the earth is flat as well. Some of the best made bike frames are bronze welded which, using your argument is pretty much gluing them together. Technology moves forward just because you can't comprehend it doesn't mean it isn't true.

This is one of the coolest methods i've seen of welding dissimilar metals http://www.youtube.com/watch?v=HvJee_1w4tA cant see any of us being able to do it in our sheds though

 

[KemppiFrog]

The comment about big motor yachts using steel ally welding is about a process that bonded the dissimilar strips with explosives. So the light superstructures could be welded to the steel hulls. But the actual welding , on the job, was to similar metals using the strip sandwich.
Bit of history: The Ford J type GT40s at Le Mans in the 60s used bonded structures and suspension mounts. So not much new here. They didn't race them, only used in practice, but they didn't break.
And the Comet jet airliner used glued structures, as do all of the current bunch. It is not stuff you can do in your shed, due to heat and pressure considerations. But it is very effective.
A roll cage does sound odd. glued structures avoid narrow stress points, the joints are usually faired in a gentle way, rather than a simple butt.
KF
Dinner calls

 

[F.J.]

I used to work in a commercial vehicle workshop and also taught panel beating for 4years. In both commercial vehicle and car repair shops adhesive is used to bond new panels back on after repair. On a middle panel of a LWB sprinter for example the panel would be cut out and all edges cleaned back to bare metal and the edges treated with the relevant primer. The 3M adhesive is then applied to top lip and side edges then clamped into place. The only welding done was to the sill which was spot welded. All this was done following insurance approved methods. These panels are classed as semi structural. Chassis section and other full structural components are to be repaired using welding, not adhesive. The same methods are used in all forms of motor vehicle repair.

 

[KemppiFrog]

Yep, the whole exterior skin of my Espace is bonded on to the steel frame, as are the door skins onto the steel frames. As it is a bit old, one door skin is parting from the frame. So some epoxy is in line to fix that.
Notice that the early Espaces were built by Matra, an aerospace outfit...

 

[lexi]

As are the later Avantime iirc

 

[KemppiFrog]

Yes, it was only the latest series of Espaces that are all steel. Bit more cost effective, but not nessessarily an improvement. Mine may be old, but no rust at all, as the steel base is hot dipped galvenized.