Body epoxy Durability

[®ob]

Not that's it's mentioned anywhere I could find...but does anyone know what the life expectancy of the chassis glue is supposed to be? I'd imagine it would be varied depending on what climate the car lived in.

[Nick]

may want to start here. The shop manual may also lead you to the answer.

http://www.sandsmuseum.com/cars/elis...echnology.html

As I understand it is a variant of the glue used on satellites - those have been up there for a while.

And I understand there are no reports from Europe of problems and the Elise has been there since 1996.

good hunting

have fun

Nick

[Goose]

As far as what type/brand used, I think it's changed at least once over the production run.

Per the "Elise - The Inside Story" video, the original epoxy was sourced from Ciba Polymers in England. I remember reading somewhere (probably here) that the current glue is sourced from one of the big guys like DuPont or PPG.

I'm going to dig up the Ciba website for giggles...

[Miguel]

Originally Posted by Goose

No dice on the Ciba website - it looks like they were sold to somebody in '99. Guess that's why Lotus is using somebody else!

From:
http://www.allbusiness.com/periodica.../682738-1.html

Ciba Polymers Is Now Vantico
Ciba Specialty Chemicals of Basel, Switzerland, has completed the sale of its Performance Polymers epoxy business to Morgan Grenfell Private Equity of the U.K. The business is now called Vantico and is based in Basel. It has three divisions, Adhesives and Tooling, Electronic Polymers, and Polymer Specialties (which includes structural composites).

And from:
http://www.polymer-age.co.uk/archive64.htm

Huntsman to get control of Vantico
June 25, 2003 The European Commission has approved the proposed takeover of Luxembourg-based Vantico Group (best known for its rapid tooling resins and Araldite adhesives) by Huntsman of the USA. The deal, announced earlier this year, involves the US investment company MatlinPatterson exchanging debt for equity in Vantico, thereby becoming its principal shareholder. MatlinPatterson is joint owner (with John Huntsman) of Huntsman Holdings, and will pass control of Vantico to Huntsman.
The EC was interested in the possibility of Vantico improving its position in liquid formulations for tooling by having access to Huntsman's diamine-based epoxy curing agents, but has concluded that the companies' relative shares in the downstream and upstream markets were unlikely to create a dominant position in tooling.

Here is their page.
http://www.huntsman.com/

[Miguel]

Originally Posted by nas213

Also, does anyone know exactly what epoxy is used for the glueing the chasis together?

From:
http://www.huntsman.com/advanced_mat...fm?PageID=5813

With the development of its patented technology to bond aluminum and introduction of new technologies using Araldite® adhesives to bond steel components, Huntsman Advanced Materials adhesives became the products of choice for producing the new aluminum Jaguar XJ, Lotus Elise, Vauxhall VX220, Aston Martin Vanquish, Morgan Aero and Audi A8. Similar technologies are being used with Araldite® adhesives to bond steel components on BMW, Mercedes and Volvo vehicles.

As a long-time supplier to the automotive industry, we have the expertise to support existing project development cycles and to anticipate future requirements. Our cutting-edge products and process solutions are geared to providing design engineers with the tools they need to generate the cars of tomorrow.

Edit2: Note they use the same adhesive for the Audi A8

From:
http://www.huntsman.com/renshape/Med...r2000_2_Uk.pdf
Note at this time it's still Vantico after change of ownership in June 2000.

The main feature of the Vantico stand is a full size, test model of a Lotus Elise
car. This illustrates the versatility of both Vantico Adhesives and Parts In
Minutes™ (PIM) across a range of automotive applications from short-run
plastic components production to composite bonding.

From:http://www.huntsman.com/structural-a...l2001_3_Uk.pdf

Araldite 2015 is a room temperature curing paste adhesive giving a resilient
bond. It is thixotropic and non sagging up to 10mm thickness and is
particularly suitable for SMC and GRP bonding. The only pre-treatment
required is a simple wiping of the surface with a degreasing agent.
Qvale currently manufacture 8 vehicles a week and hope to achieve their
optimum production level of 2 cars a day by April 2001. The Qvale Automotive
Group, and in particular its founder, Kjell Qvale, are no strangers to Britain.
Kjell Qvale created British Motor Car Distributors, which became the largest
distributor of British-made cars in the United States, handling cars such as
MG, Austin Healy, Triumph, Jaguar, Lotus, Rolls-Royce, Bentley and Jensen.
In 1970, Kjell Qvale bought Jensen Motors, a purchase which led to the
creation of the Jensen-Healey, which he developed jointly with Donald Healy.

Info about Araldite:

http://www.huntsman.com/advanced_mat...fm?PageID=5865
Edit: easier link to remember but takes you to the place above
www.araldite.com

And FAQs:

http://www.huntsman.com/advanced_mat...fm?PageID=5911

[TimMullen]

Originally Posted by thegit

The bond is not too resistant regarding shear forces the tub may encounter in certain crashes, so there are also divots securing the panels.

It's my understanding that the rivets are there mainly to hold and align the parts during assembly and curing. 99% of the strength of the joints is from the bonding.

As for how long they will last, well... I also seem to remember from information provided when the Elise was first created (over 10 years ago), that in accelerated "aging" tests, there was no degradation in the bonding over time. The bonded aluminum chassis will far outlast a typical steel chassis - even in dynamic loading properties.

There may be things to worry about with the Elise, but chassis strength and/or lifetime is not one of them.

[Miguel]

Funny I did another google search just in case I found more info, and found this link on elisetalk from two years minus one day ago from Ruediger
http://www.elisetalk.com/forums/showthread.php?t=2626

Coincidence?

Edit: Ok, one last related link:
http://www.initialdave.com/cars/tech...isbasics03.htm

Edit2: I lied, index to that last link, interesting read:
http://www.initialdave.com/cars/tech.htm

[Goose]

Actually, thegit is right regarding the rivet situation.

My comment is loosely based on the Elise video again. I played the grooves out of that video for about nine years while I prayed that the car would be imported. In one video segment, one of their test engineers illustrated the peel stress resistance of a glued test joint versus one that was also reinforced by rivets at the corners. Although the strength of the bonded joint was sufficient, the controlled tests pointed them towards using rivets for additional crash strength. Having rivets does not undermine the innovative use of epoxies in the Elise; the rivets were simply added to further improve the Elise's safety.

Arno, are you out there? I'll bet the self-proclaimed "nerd" could shed further light on this...

[The Shop Indy]

We have attempted to remove a section of the frame and even with removal of the rivets and the use of heat to release the epoxy we had problems. The technician doing the work was an FAA certified aircraft repair person who specialized in metal and composite work.

[Arno]

Originally Posted by Goose

Arno, are you out there? I'll bet the self-proclaimed "nerd" could shed further light on this...

Most of the stuff has already come by as far as I can see.

Life expectancy of the bonded chassis is indeed still 'unknown', but even one of the first built S1's right after the real test-mules called 'Ruby' is still running and AFAIK still owned by Dave Minter.

Also, as is explaind in the original Elise video...

The bonding agent used on the chassis is of a 'hot cure' type. This is the reason why the chassis is put together and then goes into an oven to be 'baked' around 190 degrees C, at which time the bonding agent cures completely and gains it's final strength.

On every car you can find stick-on thermometers. Usually on the chassis extrusion visible in the engine bay towards the passenger compartiment. These are there to verify that the chassis did indeed reach the right temperature and are checked after they have cooled down again.

As far as I know there is no (generally available) bonding agent that gives the same strenght and has the same properties, but cures at ambient temperatures.

This is basically what makes repairing the chassis 'impossible' as you'd need to 'rebake' the chassis after a repair, but that can't be done without stripping it completely bare.

The expense in labor cost would be horrendous, making this not a commercially viable option. Technically it's 100% possible, but economically it's 'interesting'.

It will be interesting to see how the chassis holds up as the years pass. It is still a bit of a guess what will happen. A lot of experience with bonding has of course been gathered in the aerospace industry, but I think someone in the Elise video does remark on the aging data from planes and crash-resistance that 'if you crash in a plane, bonding strength doesn't really matter anymore'..

Bye, Arno.

[Arno]

Originally Posted by Miguel

Could it be that they are using a different process now? for all I can see, they use Araldite 2015 and seems to me it's a room temperature adhesive.
Maybe they use a different paste for the Elise.

Yup. The bonding agent for the chassis is not listed anywhere in the service manual and such.

Just look in your engine bay and take a careful look at the aluminium extrusions of the chassis beams you can see sticking out from the passenger compartiment (the subframe bolts onto that). You'll see a thermometer somewhere and it will still read the temperature the chassis reached when it was baked.

You do find in the service manual the different BetaSeal types used to bond on the different fibregrass parts, windscreen, etc.. Aka everything that's added onto the base chassis later on and is supposed to be removable/replacable in the life of the car.

Bye, Arno.

[esprit89]

Originally Posted by Miguel

Could it be that they are using a different process now? for all I can see, they use Araldite 2015 and seems to me it's a room temperature adhesive.
Maybe they use a different paste for the Elise.

Curing at higher temperature speeds up the cure process which is desirable in a production environment. The minimum cure times for Araldite 2015 are:

50degF, 21 hours
59degF, 13 hours
77degF, 10 hours
104degF, 2 hours
159degF, 35 minutes
212degF, 7 minutes

The maximum temperature you cure at will be dictated by what the base material can tolerate and how big/what kind of oven you have.

Interestingly the product data sheet also lists lap shear strength knock downs for ambient temperature (higher temperature, lower strength), immersion in various substances (gasoline, oil, water, etc.), hummidity and heat aging.

Datasheet

The web site indicates that this adhesive Beige in colour (or it's packaging is ), isnt' the adhesive still orange/red in colour?

Michael