Polycarbonate windows use different "adhesives" than glass to secure.

[heymccall]

I don't come here a lot, BUT, I thought I'd share. I have Lexan (polycarbonate) windows coming loose (OEM) on my Caterpillar excavators, and my replacement Polycarbonate windows continually come unbonded on all my machines.

As it turns out, you CANNOT use the same adhesive and primer as one would on glass, BUT, I cannot find a qualified glass shop (one that knows what adhesive to use) anywhere in the tri-state area.


Problem 1: The boom side window (polycarbonate) in all of my C and D model Cat excavators is coming undone from the cab, but, it's not a "adhesive" failure, per se. It's a failure of the black shadow mask becoming delaminated from the polycarbonate.

Problem 2: Every polycarbonate window, whether the original reinstalled, or a new replacement, is coming unbonded from the machine cab due to NOONE in the tristate area using the correct primer and adhesive. This is occuring on both my Cat's and my Komatsu's.

Caterpillar sold me a document show what and how to do it, BUT, no glass shop has ever used the Sika products referenced, and, with the initial problem being that of Cat OEM installed polycarbonate coming undone, is Cat right when the say to use Sikaflex 255FC? I'm leaning toward using Sikaflex 295UV, with it's better stretch (elastomeric) properties and additional UV inhibitors.

Komatsu is dumbfounded and cannot find service directions or materials (adhesives) used to install their polycarbonate windows.


Does anyone know a shop versed in polycarbonate glazing install?
Has anyone ever had the Cat windows come undone?
Why is this happening only on my C and D series excavators? (Every B model here still has the OEM polycarbonate still properly attached and ssome of these are 14 years old).
How do I get my replacement Komatsu polycarbonate window to stay adhered to my PC-128?

I just want my windows to stay where they belong...

 

[Beachbum0286]

We had the top of the boom side window come unsealed on a 325D. The mechanic just used permatex ultra black to seal it back up, its been fine ever since.

 

[heymccall]

I'm wayyyyy past that stage. The C's and D's have unbonded (via failure of the shadow mask) well past 1/3 of their perimeters.

 

[cps]

Hi There heymccall, just out of interest why do you use polycaronate windows all round? is it to do with your applacaion !
I have a project coming up that i may use it for! i could ask the supplier what he recomends!!

Aiden

 

[heymccall]

I didn't "choose" polycarbonate (trade name LEXAN). The OEM did. They have used it for years which is what makes this even more frustrating.

 

[Lee-online]

The following consumables should be used for this rework:
Sika® cleaner 205, grease remover.
Sika® primer 209, primer.
Sikaflex® 295-UV, polyurethane windscreen adhesive.
Sika® Remover 208, to clean eventual spots.
Using any other compound or product may damage glazing and prevent waterproofness.


7 - Remove any excess of adhesive material from the frame of the cab using oscillating cutting tool or Cutout knife. Make sure that the thickness of residual adhesive remains between 1 and 2mm width.

8 – Clean the flanged area on the frame with Sika® cleaner 205. This step will
clean the frame from residual material or grease and will prepare the surface
to receive the Polyurethane windscreen adhesive.

Preparation of the window.

9 - Lay the new polycarbonate window on a stable and flat surface.

Polycarbonate window could be delivered with two different configurations.

Configuration 1 - with a milling all around the window and black painted area.

Configuration 2 - with a milling all around the window without black paint.

Prepare the new polycarbonate window by applying primer Sika® primer 209 to the milled area around the window. (image 1.10.1 & 1.10.2)
Use a foam brush to evenly apply primer.
For configuration 2: A second layer of Sika® primer 209 is needed. Apply it immediately after de first one without drying time.
Allow the primer to dry at least 30 minutes and no more than 24 hours at 23°C (73°F). Do not apply at temperature below 10°C or above 35°C.
Care must be taken that this application gives adequately dense coverage.

Reseal tightly container immediately after use.

10 - Using a caulking gun, apply an even layer of Sikaflex® 295 - UV, (Polyurethane windscreen adhesive) all around of the window.
Dimensions for the width and the height of the adhesive are 10 - 15mm (0.39 to 0.59 inch) (width) and 10mm (0.39 inch) (depth

15 - Wet stains or residues of Sikaflex® 295 - UV can be removed using Sika® Remover 208 (image 1.17.1) . Once Sikaflex® 295 - UV is dry, it can only be removed using a manual tool like a cutout knife. Cleaning of the hands and skin has to be carried out immediately using an adapted soap. Do not use solvents.


16 - Sikaflex® 256 will cure in 12 to 24 hours. Do not expose the cab to temperature below 10°C during 24 hours for proper adhesive curing. Do not slam the cab door for 24 hours. The excessive air pressure in the cab from slamming the door may loosen the window. It is strongly recommended to NOT MOVE or OPERATE the machine during the 24 hours following this rework. Failure to do so will eventually cause the window seal to leak.



We supply the primer and adhesive to our local glass guy and he does it for us.

 

[windyhill]

Very old tread, but update:
Sika Aktivator 205 and
Sika primer 209 for Lexan/ plastic.
Sika primer for metal frame 207
Sika 295-uv sealant.
clean up with mineral spirts.
Sika 1-800-688-7452

 

[windyhill]

Since I've been down the rabbit hole hard the last week, I finally found the guy with the answers at Sika!
I've been trying to figure out what product to use on the Lexan glass on the top of my Volvo EC140 E lc Excavator. The Sika products are great and there are lots that are used for factory applications, for instance they said the 295-uv was designed for marine applications. The above may work but it
turns out the actual Factory product for this particular funky curved factory glass is actually a product called Bostik 70-08A!
So if you have a Volvo this is what you need, (I think they are one of the only ones), It only took me a week to find the info, hopefully it helps someone else out!