Bonding lexan to metal

Junkyard Dog

Well-Known Member
Joined
Mar 21, 2005
Location
Sanford, NC
Anyone ever tried this? My skid steer window blew off going down the highway Friday and I need to put another one on. The window is available from CAT but no adhesive. It was glued on with some kind of adhesive that the parts guy says isn't available. I've searched the web but ain't found a definite answer.

Thanks 15301.jpeg
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I would think windshield adhesive would work best but not sure how it will interact with the lexan. I would drill and tap some holes in the roof and use some 1/4-20 button heads along with some windshield adhesive.
 
If you can wait a week until I am back in the states, i can get you a leeboy part number for what we use on the motorgrader cab glass
 
If ever there was a thread to make @Fabrik8 get a stiffy this is it....
 
Why not just drill 4 holes in it and put some cross tabs across the steel mesh? My Bobcat has 4 holes and threaded knobs on the bottom side for easy removal.
 
Polycarbonate is not that easy to cross-bond with most general adhesives, especially if it's hardcoated for scratch protection (which is common for protective glass so it can be cleaned without hazing as much).

Normally I would say a 2-part structural urethane would be a good starting point. You need something with some flexibility, because the Lexan and metal will expand at different rates with temperature, so something like an acrylic/methacrylate adhesive may have a lot of shear stress (and break the adhesive bond) depending on the size of the window. A single part urethane is not a great idea, because it can cause crazing on Lexan depending on the formulation (it may work, but it's a gamble). I haven't heard good things about single part urethane for Lexan windshields for example, and people often have to use screws to physically hold it in place. So if you're willing to drill some holes, a windshield urethane may work (or the screws by themselves may be fine without a sealant).

The 2-part structural urethanes would be something like Lord 7542 or 7545 (there are other brands with similar products, like 3M), and you'd also need to buy/borrow an adhesive cartridge dispenser and a mixing nozzle (probably $15 for the cartridge, plus $25 for the dispenser and nozzle). If it's bare metal, you may need a different product because there's obviously a huge different between bare metal and painted/powdercoated/primed metal.

Lord Fusor 127/128 or 147/148 might be a good choice as well, especially if you can find a local body shop that already uses it and may save you from buying extra stuff for application. It's a 2-part structural urethane as well, and seems to be rated for bare metal.

How big is that window? I'm having a hard time judging size from the picture.

RatLabGuy said:
Lexan = Polycarbonite. You need a polycarb adhesive (glue).
E.g.
Lexan Polycarbonate Glue
Click to expand...

That's for bonding polycarbonate to itself.
 
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I have thought about bolting it down but in not drilling holes in the machine. I could go thru the little square openings that are there now and maybe make a tybar piece. The sealant that is there is probably .200" tall and has little stand offs to hold the lexan off the metal. I assume to help with noise/vibration. The window is approximately 20*20". I wasn't able to find the old one but was able to make a pattern from one at work. Just going to cut one out. CAT wants $110 for it.
 
The spacers are most likely to set the proper bondline gap for the adhesive being used, so there is enough adhesive to move in shear with thermal expansion and minor impact. With a bondline that thick, that narrows down the choices for adhesives a lot (that's a pretty huge bondline thickness). That's also a bunch of adhesive, because that's minimum 80 linear inches at 0.2 inches thick and probably 3/8 to 1/2 inch wide, so easily 6-8 cubic inches (100-130cc) of adhesive. So something like the bigger 300mL cartridge of the Fusor urethanes would probably be a good choice (probably $50 for the cartridge).

If you're making a new piece, get some impact-rated stuff with an anti-mar/scratch coating, which will help with UV resistance and other worthwhile things. You should be able to get a 2x2 foot piece from a local plastics supplier or from someplace like Stockcar Steel if that doesn't work. There are a lot of grades of polycarbonate, and some are a lot better than others for what you're doing.
 
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I used it on my door polycarb panel and it’s fine. Actually still have regular ol leftover bathroom silicon holding the roof panel on. I need to polyurethane it too. But that’s all I had when it was raining and needed to go. Hasn’t blown away yet, but the polyurethane is stronger.
 
I think I've decided to try 3m window weld. It's urethane and I figure it might be able to take the movement being it's designed for Windows and windshields. I cut a new window out last night and gonna try to pick up some 3m Tonight.
 
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