Window gaskets provide sealing and insulation and can help hold window glass in place. They are made of rubber materials and installed along the edges of stationary windows such as the windshields for agricultural, forestry, and mining equipment. Window gaskets are also used with the viewing windows on machine or equipment enclosures. Because they are industrial rubber products, window gaskets like these do not include the flocked seals that are used in cars with moveable glass.
In this design and installation guide from Elasto Proxy, you’ll read about different types of window gaskets and some commonly used gasket materials. You’ll also learn about rubber part tolerances – a common source of confusion in many gasket designs. In addition, this article highlights the importance of three measurements: window glass thickness, window glass length, and gasket length. Finally, you’ll learn how to order and install locking gaskets for your sealing and insulation application.
Types of Window Gaskets
Depending on the window gasket application, engineers can choose foam profiles, D-shapes, C-channels, U-channels, or various types of glazing seals. In the mobile equipment and enclosure industries, window channels that feature a locking or self-locking mechanism are often used. Locking channels are two-piece gaskets that lock into position with a lock strip or key. Self-locking channels are one-piece window seals that do not require these attachment mechanisms.
Window Gasket Materials
To avoid gasket failure, always consider the environment when selecting rubber materials. With mobile equipment, EPDM window gaskets are typically used because they can withstand outdoor conditions. For the viewing windows on equipment enclosures, there are different considerations. For example, food processing equipment may require window seals made of FDA approved silicones. For all window gaskets, the durometer is usually between 60 and 70 (Shore A).
Window Rubber Tolerances
Rubber has many useful properties, but it can’t match the tight tolerances associated with steel. That’s because rubber is more sensitive to how heat and cold cause materials to expand and contract. The type of tooling that’s used to extrude rubber also effects part tolerances. If you’re an engineer who’s used to working with sheet metal or metal profiles, you may need to adjust the tolerances on your part drawings and consult the RMA Handbook, a resource with dimensional tolerances for extruded rubber products.
Window Glass Thickness
Measure the thickness of the window glass so that you can determine the size of the edge that your window gasket needs to grasp and hold. There needs to be enough room for the glass to fit inside the gasket, but not so much room that the glass will rattle or fall out.
Standard window channels are available for glass edges with the following thicknesses:
- 1/8 in. (175 mm)
- 3/16 in. (4.7625 mm)
- 1/4 in. (35 mm)
- 3/8 in. (9.525 mm)
- 1/2 in. (7 mm)
You can also order custom window channels with special edge dimensions.
Window Glass Length and Gasket Length
Window glass length and gasket length are especially important measurements. To determine the window glass length (WL), multiply the height (H) and width (W) of the glass. To determine the gasket length (GL), multiply WL by two. These calculations explain.
H x W = WL
WL x 2 = GL
If you buy cut lengths, remember to account for the cut length tolerances in the RMA Handbook. If you’re buying coils of rubber instead, order enough material for all of the windows that you need to seal and account for material waste from mis-cuts. Once you calculate the costs of labor and material waste, cutting your own gaskets by hand might not seem so cost-effective.
Locking Gasket Installation
During gasket installation, workers will find that there’s some extra rubber for each window. That’s by design since all rubber gaskets experience some shrinkage over time. When you install a locking gasket, push the ends together and leave the extra material in the loop that forms. Then press down the loop so that you force more material into the gap. This keeps the gasket from becoming over-stretched.
Next, spray the locking gasket with a silicone-based lubricant or soap and water. Then use a hand tool to unlock the gasket so that it’s ready for window glass installation. Install the glass on the body size first, resting the bottom of the glass in the locking gasket. Then use a plastic installation tool as you work the gasket’s lip over and around the glass. Finally, use a hand tool to the lock the gasket back into itself.
Window Gasket Design and Installation Assistance
Do you need help with window gasket design or installation? Elasto Proxy distributes window gasket materials and supplies cut lengths using our water jet cutting equipment. For over 30 years, we’ve been providing industries like mobile equipment and enclosures with the sealing and insulation solutions that they need. To request a quote or for more information, contact us.