Adhesive technology to make vehicles Lighter, Stronger, Safer, Quieter and Greener

Modern adhesive technology can help shave up to 40% off the weight of a car body according to Sika Automotive.

“In fact, the right adhesives technologies can help make vehicles not only lighter, but stronger, safer, quieter and greener too. For instance, Sika adhesives, baffles, reinforcers and dampers can help eliminate 3 dB of interior noise, while also enabling mixed-material bonding for reduction of weight,” says the company.

Sika recently opened a new adhesive and acoustic product plant in Sao Paulo, Brazil. The new factory with its adjoining technology center will manufacture adhesives and a wide range of acoustic products for the automotive market in Latin America. According to the company its products are found in more than 50% of vehicles manufactured annually. Automotive Industries (AI) spoke to Greg Moran, Vice President, Head Global Automotive Marketing, Sika Automotive.

AI: Let us unpack the claims made on the website. Where is the 40% saving in weight?

Moran: This statistic references up to 40% weight savings in the car body. The full portfolio of Sika products enables weight savings in the design and production of car bodies. A leading example is one of the first volume production vehicles introduced with significant weight savings, the JLR Range Rover. This all-aluminum car body uses five different aluminum grades instead of steel, and takes advantage of extensive use of body shop adhesives including SikaPower®and SikaSeal® as joining technologies. The result is 39% lighter than a comparable steel predictor over the previous model. It is also possible to down gauge or to re-spec the high performing metal by reinforcing areas locally, often resulting in 20 to 30 % mass savings. This is of particular interest to areas that are utilizing sandwich style metal reinforcements and in A/B/C pillars.

Additionally our Sikaflex® products enable selective stiffening of roof panels (through DVD bonding) on down-gauged sheet metals while maintaining performance and acoustic characteristics, and also bonding of steel to full aluminum roof panels amounting to 3-6kg savings per vehicle. Sikaflex® UHM 1C adhesive bonds the carbon fiber life module to the aluminum drive module on the BMW i3, and we also enable lighter design in sunroof and WOPR configurations, tailgates and hang on parts including same or mixed materials by also incorporating Sikaflex® and SikaForce® 2C adhesives.

AI: How do the products improve safety?

Moran: The focus is on reducing body structure intrusion into the safety cell (passenger compartment). This is made possible by limiting the collapse of car body structure sections and by limiting the local load on structural components and sheet metal to avoid rupture and collapse. “Crash resistant adhesives” or “toughened adhesives” such as SikaPower® have been developed for, and improve BiW structural adhesive performance of the vehicle.

Drop tower tests on crash rails and real crash tests on components that include SikaPower® have shown that the intrusion during crash events is significantly reduced due to the use of special tougheners built into the performance matrices of these Sika materials. Structural and toughened BiW adhesives transfer crash loads to and through specific target sections with targets of reducing impact forces in the case of crash.

Further safety enhancements are enabled through the use of SikaReinforcer® products; light, structurally engineered molded parts are strategically placed in body sections to prevent total collapse. The parts, composited of plastic and epoxy, or assembled with adhesive, combine with calculated engineering design and targeted placement in the body, limit buckling of sections. Additional safety applications include innovative headlamp bonding technologies, and sensor potting compounds ensuring functionality of critical systems.

AI: How can adhesives make vehicles quieter?

Moran: The use of Sika products in combination can help to eliminate up to 3dB of noise from a passenger compartment. In the body shop, the general mechanical properties of adhesives provide a factor 3-5 higher strength compared to classic BiW joining techniques (spot-welding, riveting, etc.)

Our sealing technologies including bulk applied chemistries for anti-flutter applications, which isolate vibration, and our parts technologies including tapes and highly engineered baffles fully seal body cavities; blocking and isolating common noise transmission paths and eliminate the intrusion of the elements throughout the vehicle body structure and into the passenger compartment. Interior products in the passenger compartment that contribute to lower sound levels and add comfort include SikaMelt®, SikaTherm® and SikaSense®. They are used to laminate leather and fabrics to various substrates for the wrapping door panels, dash boards, arm rests, steering wheels, consoles, headliners, visors, and surfacing load floors in those beautiful interiors.

AI: And greener?

Moran: Our program “More Value Less Impact” outlines our annual sustainability goals. In our development processes we continue to innovate and introduce products with less environmental footprint. Examples include Sika® Hydroprep, our water based family of pre-treatments which eliminate an estimated 200,000 liters of solvent based VOC emissions each year, our patented i-cure technologies which emit less VOC while curing and our SF (Safety First) series of hot melts that are MDI free with no hazard classifications addressing worker safety.

Further, the use of our cold applied SikaPower® body shop adhesives, Sikaflex® and SikaForce® lessen utility costs for heated application, and directly reduce the number of spot welds introducing utility cost savings in ovens and welders. There are exponential benefits when we link the performance attributes of our products to the after application contributions including the use of thinner gauge metals, the joining of families of dissimilar materials/substrates, such as aluminum and CFRP to steel, resulting in finished assembly weight/material savings, less CO2 generated, and better mileage.

AI: What is the significance of your new factory in Sao Paulo, Brazil?

Moran: Globalization of the automotive market as a megatrend drives selection of suppliers with global reach to establish local presence. Our investment here offers business advantages in managing shorter supply chains pre and post product, and the ability to plan to customer requirements in short order. The new design center helps customers to meet local specifications unique to the region.

AI: Please tell us about SikaBaffle®-230.

Moran: GM SikaBaffle®-230 is our latest product within the range of heat expandable tapes, and performs as both a sealant and acoustic tape for the automotive body shop. Ideal to seal small hollow body cavities, SikaBaffle®-230 represents multiple benefits for OEMs such as shorter design time, ease of application and very low investment cost.

A key attribute of this product is its versatility; while it can be used anywhere in the vehicle body, including the wet areas, it shows excellent adhesion to a wide range of steel and aluminum substrates, and thus supports lightweight initiatives. Combined with reduced VOC emissions, SikaBaffle®-230 is the product of choice for sustainable solutions. The product is available globally.

AI: What other technology can we expect?

Moran: Our future focus is on unique combinations of the best of all worlds in adhesive and sealing applications. Our technologies are in continuous development to address megatrends that drive the industry. Lightweighting is certainly a relevant one. Recent introductions include SikaPower® MBX technology (Mixed Bonding eXcellence) which solves the joining of multiple combinations of materials and addresses Delta/Alpha effects; the differing thermal coefficients of expansion and contraction of mixed materials.

Other focus areas include developing answers to changing production processes including low and high bake temperature technologies which introduce new demands on products to meet the future conditions. Technologies including Sikaflex® Ultra-High Modulus and Ultra-Low Modulus materials will provide maximum strength with engineered flexibilities and consistent performance curves over the extremes in temperature ranges. A new range of 2C products for assembly is on the way, we will soon introduce high-performance additions to our body and cavity acoustics sealing range, as well as new entries in the area of reinforcement.

As the industry evolves so will our solutions. All of our technologies are grounded in our core competency of elastic bonding, and continuous innovation is a constant to surpass the demands of our customers to allow freedom of imagination in their design processes.

AI