Car makers opt for lighter materials such as polymer and aluminium which are not suitable for welding. Hence high-performance adhesives or bonders have a growing demand. Besides, manufacturers design cars using adhesives due to stricter emission norms.
With the shift toward lightweight vehicles, the automotive industry has seen changes in the requirement of products. This, in turn, has also impacted the technologies which help create newer and better suited products. In the automotive industry, adhesives are one such indispensable component. Consumer or environment-driven factors are major reasons due to which adhesives are extensively gaining a foothold in the automotive industry. The automotive adhesive industry in India is directly affected by emerging trends. The dynamics are steered by factors such as increased use of plastics and lightweight materials in automotive applications and increasing use of water based adhesives.
Structural adhesives (SA) are chosen for a multitude of assembly operations. “They can join dissimilar materials without galvanic corrosion, are amenable to a number of different geometries, don’t concentrate stress at a few localised spots and don’t require refinishing steps or leave protrusions,” explains Rajesh Balakrishnan, CEO, Industrial Products Division, Pidilite Industries. Structural adhesives also play an important role in the move to composite materials, which allow for significant weight reduction with comparable stiffness, compared to metals. Adhesives bond a wide array of automotive assemblies, including windshields, structure, interior components, brakes, wire harnesses, exterior trim etc.
“Lighter, thinner materials can often be used without sacrificing strength. Costs can be lowered by reducing material requirements and weight through eliminating drilling, welding, screwing, and similar operations. Common examples of structural adhesives include epoxies, cyanoacrylates, and certain urethanes and acrylic adhesives,” Balakrishnan reveals.
Cyanoacrylates are another type widely used in the automobile industry which are solvent-free, one-component, room-temperature curing adhesives. “When pressed into a thin film between two surfaces, cyanoacrylates cure rapidly to form rigid thermoplastics with adhesion to most materials,” informs Balakrishnan.
Thread lockers represent another way that adhesives can complement mechanical fasteners in an assembly. Once tightened, a threaded fastener stays in place mostly through friction. As the material cures, it completely fills the tiny gaps between the interfacing threads, locking the fasteners in place. Liquid gaskets are adhesives that take the place of die-cut or moulded solid gaskets made of cork, rubber and other materials. They have many automotive applications, including oil pans, oil seals, transmission pans, crankcases, axle covers, oil and air filters, etc.
Barun Bharadwaj, Business Director, Transport and Metal, Henkel Adhesives Technologies India explains that there is growing demand for high-performance adhesives or bonders, since OEMs opt for lighter materials such as polymer composites and aluminium which are not suitable for welding. These modern adhesives not only fill small gaps in various car body sections but are also used to hold together and stiffen load-bearing parts.
Higher disposable income and with the rise of the millennials, there is a significant rise in the auto manufacturing units in the APAC region. “Because of this, we anticipate a surge in the demand for industrial adhesives for automotive applications in developing nations like India and China, where major adhesive manufacturers and auto makers have already set up base to meet the customer demand locally,” states D S Bhattacharya, General Manager, R&D, Automotive & Automotive Aftermarket, 3M India.
Unlike the established markets in Europe and America, in India, everything boils down to the system cost. Despite the relatively lower cost of labour, for the adhesive market to gain traction, it will require some amount of cost-innovation on the automation front. “It could start with localised semi-automated dispensing units to fully-automated end-to-end assembly lines thereby increasing productivity, improving quality and reducing costs in the long run,” suggests Bhattacharya.
Adhesives in the Indian automotive industry are expected to grow at a CAGR of 8.4 per cent by value from 2019 to 2022. Within the adhesives in the Indian automotive industry, the polyurethane adhesives segment has the largest market. “It has better mechanical properties, and an increase in automotive production is expected to drive adhesives consumption,” says Balakrishnan.
Structural adhesive plays a major role in reducing the weight of the vehicle which in turn increases fuel efficiency. Pidilite has developed acrylic structural adhesive which would help in bonding plastic parts. “Car makers using lighter materials such as composites, aluminium etc. are unsuitable for welding, hence custom-made adhesives must be used that can absorb the shock or crash. At the same time, stricter emission norms means a car has to be fuel efficient and less polluting which compels a manufacturer to design cars using adhesives,” states Balakrishnan.
A significant contributor towards lightweighting is the need for more fuel-efficient vehicles on the road. “At the same time, with the Corporate Average Fuel Economy norms coming into play, which requires cars to be 30 per cent or more fuel efficient from 2022 and 10 per cent or more between 2018 and 2021, it is imperative to meet this rising demand,” opines Bhattacharya. Adhesives, when compared to the conventional methods of bonding or joining, have proven to be superior in performance while at the same time simplify the assembly process (thereby improving the manufacturing productivity) in many cases.