Rear window mounting on sheet metal body

[Suhrud Ghatpande]

I want to mount rear window flush with the surface of the body. with the current design the rubber rails/seals project out of the body. What is method or process to achieve what I'm looking for? Directly bonding can be a way but that will make window susceptible to cracking?

Please let me know if I need to be more specific and in what particular area?

Thank You.

 

[BrianPetersen]

Practically all current cars have both the windshield and the rear window essentially glued on using a special adhesive that is meant for this purpose, in order to achieve precisely what you are after. Any good local auto glass shop will have the right adhesive.

The glued-in windows do contribute to bodyshell stiffness. The underlying bodyshell does need to be sufficiently rigid and properly designed so that it's not completely relying on the glass for stiffness and doesn't transmit stress concentrations to the glass.

 

[Tmoose]

"will make window susceptible to cracking?"

What is the method used to attach the window glass now?

I think "the answer" depends to a large degree upon the "body" in question.
Some of the examples below are not "sheet metal". But as is so often the case, the geometry probably gets more votes than the material anyway.

https://autoweek.com/sites/default/files/styles/gen-932-524/public/Model A All - 1600x900.jpg

- or -

https://i.kinja-img.com/gawker-medi...gressive,q_80,w_1600/qs0bx1ea6zrvhidc9czx.jpg

- or --

https://cdn.bringatrailer.com/wp-content/uploads/2017/06/c-11.png

 

[Suhrud Ghatpande]

It is a bus body and I want the fitting to be done as per the image. Any inputs where to start from?

 

[BrianPetersen]

You've already been told the answer!

 

[Suhrud Ghatpande]

@ BrianPetersen I know normally polyurethane is used, my question was also about process. In mass production you will at least need a robot to apply glue/polyurethane along its periphery as doing manually will consume a lot of man hours. Is there any easy way to do the same or any substitute idea?

 

[MikeHalloran]

The people who replace windshields for a living, apply the adhesive manually, and pretty quickly.
At least some of them use a suction cup equipped arm to assist, so one person can do the job.

I think the trick is that the adhesive is applied as a pretty thick bead, and then flattened as the windshield is manually pressed flush with the body surface, perhaps with simple tooling or a small crew.



Mike Halloran
Stratford, CT, USA

 

[Suhrud Ghatpande]

@Mike I'm talking about incorporating this procedure on assembly line, windows will need curing time as well I suppose? I'm not an expert on assembly or manufacturing engineering, so is that feasible?

 

[MikeHalloran]

An adhesive supplier will have your answers.

Mike Halloran
Stratford, CT, USA

 

[BrianPetersen]

There's another design feature with this style of window, which may have escaped your attention. All of them nowadays have a black coating applied to the glass itself, on the inside (on the surface that gets glued), all the way around. The adhesive isn't actually sticking to the glass ... it's sticking to that coating. That coating is "printed" onto the glass (at the glass manufacturing plant) and it is then cured in an oven. That coating is really, really tough, and it is really, really stuck to the glass.

A big part of why that black strip is there, is that it covers up the adhesive bead, which might otherwise be slightly uneven or unsightly.

As for the speed and consistency of sealant application ... whether you choose to do it by robot or not, depends partly on your production rate (economics) and partly on the importance of consistency and repeatability. A robot will do it more consistently than a person will.

In auto manufacturing for modern passenger vehicles, that sealant application is ALWAYS done by robot because of this.

 

[DAVIDSTECKER]

Many adhesives can be accelerated, via a spray, UV, or water in the case of RTV silicone.
There is also a double sided tape out there that is crazy strong, it's being use to hold semi-trailer together and windows in sky scrapers.

 

[Suhrud Ghatpande]

@brian thank you for suggestions.

@david do you know of any such specific type strong double sided INDUSTRIAL GRADE tape?

Suhrud G

 

[DAVIDSTECKER]

Link
If the link doesn't take you to the search results, look for acrylic foam tapes.

 

[bentwings2]

We use 3m VHB tape to bond sheet metal skins on trailers. I surely would not want to use this on a glas or plastic window. It doesn’t come off and it it terribly good. We use heat and special knives to cut it to remove damaged panels. It is extremely hard to remove.

For a window we use standard window adhesives. At least you can remove then down the road.

 

[Suhrud Ghatpande]

@bentwings2 any specific adhesives you know, suitable for this application?

 

[GerardNavarrete]

I think VHB tape is suitable for the wood, its better for it. But it does not stick properly on the metal or glass body I supposed.

 

[MikeHalloran]

I have had disappointing results with VHB tape in medical electronics, which is a generally benign environment.
Mostly metal to metal, with careful preparation and all that rot.
It sticks just fine, and passes any test you can imagine.
Then, just inside of a year, our warranty period, the bond separates, instantaneously, for no apparent reason.


I would still use VHB as fixturing for RTV adhesive, but not by itself.



Mike Halloran
Stratford, CT, USA