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×The integrity of any vehicle relies on all its components doing their jobs, no matter how small or simple. Windscreen seals are one such small and simply designed part that provides an ingenious benefit, keeping the vehicle in safe working condition.
When manufacturing windscreen seals, only one material comes out on top: rubber, specifically extruded rubber. Rubber extrusion is a process made for windscreen seals. In this article, we explain.
Windscreen seals, strips, or gaskets, sometimes known as weatherstripping, are essential in keeping the car's interior free from water, air, or debris entering through the front. They form a seal between the windscreen and the car's body.
Key uses of a rubber windscreen seal:
Weatherproofing the vehicle from rain, snow, and debris
Minimising the noise of the road and other external elements
Supporting the structural integrity of the windscreen
Protecting the windshield component by absorbing and reducing vibrations by way of vibration-dampening
Cars are not the only vehicles that have rubber windscreens; they’re also needed in boats, aeroplanes, and types of heavy machinery like tractors and excavators.
Rubber is a popular material for the manufacture of windscreen seals, thanks to its resilience to the varying elements in vehicle climates. Rubber’s high elasticity helps it conform to the shape of the windscreen, assists with installation, and absorbs vibration and noise.
Let’s take a look at the qualities and properties of different types of automotive rubber seals for windscreens.
Resistance to extreme temperatures and UV radiation
Ensures a long lifespan and reduces the need for frequent replacement
Easily conforms to the windscreen shape to provide a tight seal and stress-free installation
Recyclable, reusable, and highly durable
Silicone rubber extrusions are ideal for more extreme, harsh weather conditions.
Good resistance to weathering and UV radiation in a range of climates
Generally more affordable than silicone
Recyclable and performs well in harsh weather conditions
Can become brittle and stiff over time
Highly resistant to chemicals and oils, making it ideal for industrial use
Known for its resistance to extreme temperatures
Durable and flexible
Good resistance to abrasion, heat, and water
Highly resistant to UV radiation, ozone, and weathering, making it ideal for marine environments
Good durability and flexibility in all climates
Highly resistant to hot and cold temperatures compared with nitrile rubber
Carefully selecting the best type of rubber for a windscreen seal depends on its application: the environment where it will be used. Silicone and EPDM are the best for extreme temperatures and offer eco-friendly benefits. Nitrile and neoprene are chosen for specific environments, nitrile for industrial settings where chemical and oil exposure are a hazard, such as heavy machinery, and neoprene in marine vehicles to protect against specific sea-bound weathering.
In situations where rubber is unsuitable, foam and PVC are sometimes used. Foam is lightweight, porous, and an excellent insulator. It is also used as a second seal or as a rubber extrusion for classic cars to preserve the integrity of the original design. It's also used as a temporary seal. It is cost-effective and easy to install.
PVC (Polyvinyl Chloride) is a robust material for making windscreen seals with relatively low maintenance. It’s highly resistant to elemental exposure without degrading and is also resistant to some chemicals, oils, grease, and petrol. PVC is lightweight and easy to cut to shape. It is commonly used in cars, lorries, and buses and is a popular, affordable choice where rubber can’t be used.
Installing rubber windscreen extrusions correctly ensures the longevity of both the seals and the vehicle. Here’s a step-by-step:
Ensure the windscreen is completely clean and dry before installation, and ensure it is free of oils. It is recommended that you use a glass cleaning solution and a lint-free cloth.
Warm the rubber seal to increase its flexibility. You can do this by soaking it in hot water or laying it in the sun.
Apply a good lubricant to the seal, such as KY Jelly or Simple Green cleaner.
Physically installing the windscreen seal requires two or three people to work together. Start by installing the seal onto the windscreen to fit snuggly around the glass.
Wrap waxed twine around the windscreen seal in the outer groove, leaving 6” extra around each end to use as pull handles. It’s recommended to wrap the twine around twice. This will help get the rubber over the metal lip of the channel when installing the windscreen. Tape both ends of the twine to the glass to keep them out of the way and ensure the twine doesn’t fall out of the groove. Make sure these are taped on the interior side of the glass.
Sitting inside the vehicle, place the windscreen on your knees, with the inside part face-down. Let the windscreen sit in the sun for another 10–20 minutes to allow the seal to soften further.
Insert any kind of reveal moulding, if needed, before the glass is installed back into the vehicle.
Lubricate the outer groove of the seal.
One person inside the vehicle should push the glass into the frame. Start by ensuring the bottom of the windscreen is pushed down into the frame first.
At the same time, the other person should begin to slowly pull the twine out of the seal at a 90-degree angle to the glass. Keep going until the lip of the seal is completely pulled out over the metal edge.
Problem | Details | Solution |
Misalignment and gaps | Misalignment of the windscreen, resulting in gaps, causing water and air leaks. | Use a 3M windshield glass sealant to fill gaps. Ensure bolts are properly aligned and tightened to eliminate gaps. Use masking tape to protect areas around the seal during application. |
Difficulty installing rubber seals | Rubber seals are challenging to install due to their density and stiffness. | Soften the seal with hot water or a heat gun to make it more pliable. Use silicone spray, lubricant, or soapy water to lubricate the seal. Tools like a rubber mallet and seal removal tool can aid in installation. |
Cracking and Degradation Over Time | Rubber seals can dry out, become brittle, and crack over time, leading to water leaks. | Regularly inspect and clean the seals to prevent dirt accumulation. Apply silicone-based lubricants to maintain flexibility. Replace seals as soon as signs of wear are evident. |
Ensuring a Proper Fit | Seals may not fit properly, causing water tightness and structural integrity issues. | Ensure that the replacement seal matches the vehicle's make and model specifications. Use lubricant to help fit the seal correctly and check for gaps or misalignment after installation. |
Water Leakage | Water leaking into the car due to a compromised seal. | Identify the source of the leak using a water test. Use flowable silicone sealant to fill small gaps and ensure a watertight seal. For larger issues, consider professional repair services. |
Wind Noise | Excessive wind noise indicating a poor seal. | Check for any gaps or misalignment. Apply additional sealant where necessary and ensure the seal is compressed correctly and in contact with the windshield. |
Temporary Fixes | Immediate need to stop leaks before professional repair can be done. | Use duct tape or temporary sealants as a short-term fix. To avoid long-term damage, ensure these are removed before permanent solutions are applied. |
Using the Right Tools | Inadequate tools leading to improper installation and potential damage. | Use a proper sealant gun, utility knife, and masking tape for clean application. Consider using a rope or cord method to pull the seal into place for difficult installations. |
Continuous development in the manufacturing process of rubber extrusion means design innovations are constantly taking place. Here are some innovations that make rubber windscreen extrusions even better for their intended application.
This involves merging two or more materials through a single die in the extrusion process to form a single structure. In doing this, manufacturers can produce a rubber seal with numerous structural benefits, such as a strong attachment base with a softer compound that enables a tighter seal. Multi-durometer extrusions offer exceptional compression set properties, easy installation, and minimised stretch, making them ideal for vehicle windscreen seals.
This involves co-extrusion of EPDM with different hardness levels within the same profile. This technique combines hard and soft EPDM materials in a single extrusion process, creating a seal with varied properties. The harder segments provide structural integrity and attachment points, while the softer sections ensure a snug fit and effective sealing. This improves the overall performance of the windscreen seal, particularly in maintaining a tight seal against the windshield and car body.
Browse our blog for more details on rubber extrusion applications and the properties of extruded rubber. You can also find out about all the rubber extrusions we produce.