Multiple solutions for the automobile industry

The automotive industry is one of the largest industries in the world, producing 80 million vehicles per year. Production figures that require a high degree of automation. In this article, we present solutions for efficient, precise and economical production.

With SONDERHOFF SYSTEM SOLUTIONS, Henkel offers the automotive industry the advantage of obtaining material, machine, and contract manufacturing (subcontracting) from a single source. The customer selects the right SONDERHOFF material system based on polyurethane or silicone for sealing, bonding, or potting his components. In addition, he receives the SONDERHOFF mixing and dosing system for the fully automatic application of these 2-component materials. And the customer has access to Henkel's extensive adhesives portfolio, as well as the offer of order acceptance by Henkel's contract manufacturing sites (subcontracting). The Formed-In-Place-(Foam-Gasket) technology, used for sealing, bonding, and potting components, has become established as an efficient, precise, and economical manufacturing method, especially in automotive engineering, where large volumes and complex component geometries are involved.

With the increasing technical development of the automobile, areas such as the application of gaskets, adhesives and potting materials to various components are becoming increasingly relevant. Foam seals and potting are used, for example, to protect automotive electronics from corrosion caused by moisture. Adhesives are indispensable for lightweight construction and electromobility. 


Requirements of the automotive industry

In the automobiles produced today, sealing, potting, and bonding applications based on polyurethane or silicone can be found in very many places, such as for components in the engine and interior, for lighting, bodywork, and electronics. There, they serve as dust, chemical and moisture protection as well as vibration damping.

The requirements for the various material systems are very different. These are often specified in a separate standard, e. g. DBL 5450/5452 or TL 848/577-A. The resistance behavior of the seal to the various media is always dependent on contact duration, temperature, and the concentration of the medium. Both polyurethane and silicone seals achieve high IP protection classes in combination with the respective overall design. The International Protection (IP) class tests provide information on how protected electrical devices and products are from various environmental influences. In the area of media resistance and at high temperatures, however, silicone shows better behavior. In some cases, damage to the seal can also be prevented by modifying the design of the component. Simple storage tests of the sealing material in the respective contact medium therefore only allow limited conclusions to be drawn; the sealing behavior must always be tested and evaluated on the overall design.

For applications in the temperature range from -40 °C to +80 °C, polyurethane seals are suitable for sealing against dust and moisture. In areas with a permanently higher temperature load of up to + 250 °C or for sealing against more aggressive media, silicone systems are used. High temperature resistance is generally required for applications in the engine area. Here, however, it must also be critically questioned whether the seal is actually permanently exposed to increased temperatures, since the use of silicone seals is associated with significantly higher costs.

At Henkel, a consistently high quality of sealing, bonding, and sealing of components is already determined by the correct selection of raw materials for the formulation of the material systems. However, the safety and accuracy as well as a high level of operating convenience of the mixing and dosing systems are also very important for a precise and trouble-free application process of the materials to the components. Equally responsible for this is the precise interaction of different setting parameters and additional functions of the metering machine. SONDERHOFF mixing and dosing systems also enable flexible adaptation to different production situations in the automotive industry, including changing batch sizes, increasing variant diversity and component complexity.


High process reliability with FIPFG sealing technology

Due to the high level of automation in car manufacturing, material application must also be highly automated. In recent decades, foamed seals made of polyurethane in particular, but also silicone, have become the standard. These gaskets are applied directly to the component to be sealed in a fully automated process using FIPFG (Formed-In-Place-Foam-Gasket) technology with the aid of modern mixing and metering systems. The polyurethane foam then cures under room temperature to form an elastic flexible foam gasket. Two- and three-dimensional parts are thus dispensed with the same contour accuracy as components with and without grooves. With FIPFG technology, significantly better sealing results are usually achieved than with conventional gaskets inserted by hand, while at the same time saving costs due to automation.

All machine, material, and process data relevant to quality assurance are automatically logged in SONDERHOFF mixing and dosing systems and can thus be retrieved at any time. The FIPFG technology, together with the traceability of the preceding processing sequences of the plant, ensures reproducible production quality of the foamed components. This enables the zero-defect tolerance required in the automotive industry. The high process reliability in turn enables faster production speeds and thus higher productivity in the automotive industry.


Low-emission foam gaskets for clean air in cars

Increasingly, plastics used in car interiors are required to comply with emission values, i. e. to emit as few substances as possible into the environment, in order to protect vehicle occupants. The plastic components must not emit any pollutants that could endanger health, even at very high temperatures in the car. However, the required limit values vary depending on the manufacturer's standard. In general, however, they can be described as very demanding. After all, the aim is to protect the vehicle's occupants from harmful substances.

The minimization of emissions is achieved through the selection of material raw materials. In the case of sealing foams, this means that highly volatile components, such as blowing agents, oils, or plasticizers, must not be used. SONDERHOFF FERMAPOR K31 LOW-EMISSION polyurethane foams meet the strict limit value requirements of all major automotive manufacturers. For example, they meet the target values of the manufacturer's own specification DBL 5452-13 from Daimler. Here, the target values for VOC emission are 100 µg and for fogging 250 µg per gram of polyurethane. This allows high VOC levels in the air inside the vehicle to be significantly reduced. Irritation of the eyes, nose, throat, skin, or allergic effects are thus avoided. VOCs are volatile organic compounds that are not always firmly bound into the molecular structure of plastics or adhesives. The low-emission foams seal filter housings for the fresh air intake in the driver's compartment, for example. They ensure a leak-free fit of the filter on the air intake duct in the air conditioning systems of cars, so that no unfiltered air gets past the filter into the passenger compartment.

Too much VOC in the air also often causes fogging. VOC particles in the air move from warm to colder zones and separate there. In cars, this can lead to fogging of the windshield or the inside of the headlights. In extreme cases, this could impair the road safety of drivers. The low-emission sealing products, which are in particular demand from car manufacturers and their suppliers, thus make a decisive contribution to reducing the fogging effect and VOC pollution of the air inside the car.


Fast-Cure foam gaskets for high-cycle process manufacturing

When applying a seal to a component, the cycle time with which the components are fed to the mixing and dosing system and with which they are subsequently processed is of very great importance. Modern mixing and dosing systems have therefore always worked very quickly and with high precision. However, components with a foam seal that has just been applied generally require a certain amount of time before they can be further processed. The reason for this is the crosslinking reaction of the material components polyol and hardener. It must be completed before the gasket surface is tack-free and parts handling is possible. The parts can only be installed once the seal has fully cured. As a rule, foam gasket curing times range from 25 to 120 minutes.

In automotive manufacturing, however, with high-cycle process production, rapid parts handling is necessary after just a few minutes. For this purpose, the bonding time can be significantly reduced by using so-called fast-cure systems based on polyurethane. The surface of the SONDERHOFF FERMAPOR K31 FAST-CURE foam seal is tack-free at room temperature after only approx. 120 to 180 seconds, depending on the formulation. The foamed components can thus be further processed quickly in subsequent manufacturing processes and thus installed earlier. This saves energy costs, possible costs for intermediate storage of components, investments in annealing ovens or transfer belts for long curing times. Faster further processing and thus earlier final assembly of the components thus lead to considerable time savings in the entire manufacturing process, to lower unit costs and to more efficient production.


Typical applications in the automotive industry

Foamed gaskets based on polyurethane or silicone are found in vehicles in the interior and engine compartment, among other areas, as well as for parts of the body, lighting, and automotive electronics. Typical applications for foam gaskets include door modules, which for years have been fitted with directly applied FIPFG gaskets as standard. The door modules house speakers and power windows, whose electronics must be protected from moisture and dust. Other standard applications include the sealing of plastic housings, e. g. for electronic components or "third brake lights," for which red-colored seals are often desired. However, polyurethane and silicone seals can also be set in other colors. An example of a sealing application with increased requirements is the timing belt cover. It is located in the engine compartment and is provided with a silicone seal because of the temperature stress there.


Polyurethane adhesives for lightweight automotive construction

Thanks to new materials and material combinations, the design possibilities in lightweight automotive construction have become more versatile. Automotive components and add-on parts made of thermoplastic or thermoset plastics (sometimes fiber-reinforced) or plastic components with metallic components are increasingly being bonded with 2-component polyurethane adhesives. In vehicle construction, this includes a wide range of components, such as GRP sandwich bodies, KTL-coated metal frames for glass sunroofs, parts made of PMMA or PC with scratch-resistant coatings, roof panels, trim strips and spoilers, and ABS- or PP-based tailgates.

Henkel's extensive adhesives portfolio is available to the automotive industry for this purpose. For example, 2-component polyurethane adhesives, they enable optimum adhesive results for components made of different materials. They also meet the high mechanical and climate resistance requirements. The perfect bonding process requires precise mixing and metering of the adhesive components. SONDERHOFF mixing and dosing systems ensure this, with adherence to a precisely defined mixing ratio, metering accuracy throughout the process, and systematic process monitoring.


Conclusion for the automotive industry

The Formed-In-Place (FIP) technology for the fully automated application of liquid to paste-like SONDERHOFF material systems made of polyurethane or silicone directly onto the components has established itself as the production standard in highly automated vehicle manufacturing. The SONDERHOFF mixing and dosing systems used for this purpose can be very easily integrated into existing production lines and concepts.

With the FIP sealing technology, very different component geometries are precisely metered in high volumes with soft foam seals, adhesives, or potting compounds in reproducible quality. The raw materials used are utilized almost 100% and thus there are no punching or cutting losses.

The application possibilities for foamed gaskets are particularly diverse and can be excellently adapted to the requirements of the automotive industry. In addition to emission behavior, temperature, and media resistance, this involves the good recovery behavior of a foam seal, particularly suitable for repeated opening and closing for maintenance purposes, and flexible hardness adjustment and other mechanical properties such as tensile strength and elongation at break. The requirements of the various automotive standards must be taken into account, as must the requirements arising from the specific application.

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Florian Kampf

Sonderhoff (part of Henkel AG & Co. KGaA)

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