Enabling better and safer vehicles with bonded vehicle glass

Elastic adhesive bonding is the dominant joining technique when different materials are combined. One could think that all vehicle glass is installed using adhesives, like in passenger cars produced today. Even though adhesive bonding presents many benefits in vehicle assembly, still today, many newly built commercial vehicles are equipped with gasket-installed windshields. Trends in the heavy truck and last-mile delivery van market design indicate a further significant shift towards adhesive bonding; with this article, I like to explain the reasons.?

Why are gaskets still used?

In many commercial vehicles, the windshield is not yet used to reinforce the body structure, nor is the windshield of a truck classified acc. FMVSS 212 as a safety-relevant part like in a passenger car. While gaskets are relatively cheap to buy, they are labor intense and exhausting for workers to install in the factory. Possibilities to automate the installation are limited. Our research confirms that vehicle manufacturers are not the limiting factor in shifting toward adhesive bonding.

However, many vehicle fleet owners request gasket-installed windscreens to facilitate faster glass replacement in case of a crack or damage. While in Europe, Asia, and Latin America, bus windows are fully bonded, the US bus design is dominated by rubber gaskets. The American Public Transport Association (APTA) Bus Procurement Standard requires rubber gaskets for easier glass replacement.?

Trends

Driven by safety, durability, and comfort requirements, we see a continuous shift from rubber-glazed windows towards adhesive-bonded ones. Vehicle manufacturers understand the possibilities adhesive bonding allows in manufacturing and vehicle design and safety. Where design freedom exists, bonded glass is the way to go. ?

India – Heavy Truck

The latest Eicher light, medium and heavy-duty trucks have been designed for improved driver comfort and compliance with BS VI emission standards. The new Pro 2000 model cab incorporated a windshield bonded with Sikaflex? Booster adhesives. Since the plant was producing existing cabs with rubber-gasket glazed windshields, space for their installation was limited, and coping with the adhesive curing time was a critical aspect for the engineers.

Sika provided a breakthrough solution to meet the needs of Eicher Truck. The time for the adhesive to reach adequate strength could be reduced to match the assembly process. Additionally, VECV invested in robotic automation of the adhesive application, with Sika support for process validation, equipment design, and cost optimization [Download the Case Study]

USA - Last Mile Delivery

E-commerce, electrification, driver and pedestrian safety, and concepts towards autonomous vehicles influence the design of upcoming vehicles for last-mile delivery. US Postal Service, Amazon, FedEx, and UPS partner with vehicle manufacturers to develop their next-generation delivery vehicles.

In the case of the U.S. Postal Service, the current fleet of long-serving Grumman LLV mail trucks, will be replaced by a new generation of mail delivery vehicles dubbed “Next Generation Delivery Vehicles” (NGDVs) manufactured by Oshkosh Defence (OSK.N). The new vehicle is a solid commitment to driver and pedestrian safety. It is equipped with driver-aid features such as forward collision warning, blind-spot warning, telematics compatibility, and a backup camera. In addition, it has a large (and bonded) front windshield that offers drivers a much better view of what lies ahead of them- pedestrians, cyclists, or other cars [Read more about the USPS vehicle].

Is replacing windscreens still an issue?

Around vehicle glass, an entire industry has developed to replace windscreens and windows professionally. In passenger cars, innovative adhesive technologies reduced the vehicle downtime significantly. As a leading supplier to the industry, Sika has been at the forefront of innovation for the last 40 years. Nowadays, professionals can replace a passenger car windscreen in about 1 hour from start to finish.

In commercial vehicles, the technical requirements are different; typically, screens are heavier, they are often placed fully vertically on the vehicle, and torsional and wind loads need to be considered. In the case of a bus or train, passengers may also be leaning against the glass. New adhesive developments like Sika’s PowerCure adhesives combine ease of use and versatility for the replacement application with fast curing speed. In many cases also a windscreen on a truck or bus can be replaced within just one or two hours [Read the Truck Glass Story].?

Technical Requirements

Polyurethane adhesives are the indisputable standard for vehicle glass bonding. There are good reasons why vehicle producers rely on the unique performance of Sikaflex polyurethane adhesives since the windshield fulfills more functions than just keeping the rain out.

In today’s cars, vehicle glazing is an integral part of vehicle construction, design, and safety. This places high demands on the windshield adhesive, such as increasing the modulus of rigidity, high initial strength for automated assembly, and aiding with protecting the bodywork from corrosion. Today, the airbag system is an essential part of the passive safety system and is only made possible by the strength of the windshield bond.

Loads and lifetime expectancy in people moving vehicles are significantly greater than in passenger cars. High requirements to withstand harsh conditions from weather and aggressive cleaners used to remove dirt and graffiti are to be considered. Sikaflex polyurethanes are the standard for both commercial vehicle production and glass replacement globally.?

Sika Solutions for Commercial Vehicles

Glass installation in vehicle manufacturing starts from small scale, manual installation to fully automated installation in heavy truck. Sika offers support and solutions that help engineers to overcome basically any challenge. Sikaflex Booster and PowerCure adhesives are the ultimate solutions for OEMs seeking excellent mechanical properties with the shortest possible full cure time, and provides the opportunity to have the same system accelerated from line application to repair [Find our more about Sika’s solutions].

Get Support

Sika is present in more than 100 countries all over the world. We employ local experts to talk your language and provide access to our vast network of global experts.

Sika’s Technical Services provides extensive support throughout adhesive bonding projects. Our experts also guide you in defining the adhesive bonding process and train your staff about using products and working steps. Sika also supports process audits and helps identify areas of improvement, process, and cost optimization.?