Laser processing in automotive manufacturing
The automotive industry is one of the largest application areas of laser materials processing.
The industry is, as described by the McKinsey Center for Future Mobility, “a growth engine of Europe’s economy”, generating approximately 7% of the EU’s GDP in 2019.
This was, of course, before the disruption caused by the pandemic, with automotive production not yet having recovered to pre-Covid levels – in part due to ongoing supply chain constraints. However, growth within the European automotive sector is trending upwards. For example, almost 8 million passenger vehicles were produced in the EU during the first nine months of 2022.
This was a 5.8% increase in units compared with the same time period in 2021.
Lasers have long played a major role in optimising automotive manufacturing and thereby facilitating growth within the sector. For most vehicles, almost every area, both inside and out, will contain parts that have been processed by lasers. This is due to them offering exceptional versatility and reproducibility, with a single laser machine being capable of processing a wide array of automotive components with great precision and speed. They are extremely automatable, cost-effective and low-maintenance tools, deployed in high-throughput automotive production lines for applications such as cutting, welding, brazing, marking, surface treatment, drilling, 3D printing and cladding. Lasers can be used to process a wide range of complex 2D/3D automotive parts made from materials including metals, plastics, glass, rubber and textiles.
One of the main stages of vehicle production in which lasers are applied, particularly for cutting, welding and brazing, is known as body-in-white (BIW) manufacturing. This is the stage during which the steel frame components that form the basic structure of a road vehicle are cut and joined together.
Vehicle bodies, doors and frame components are generally made from various grades of press-hardened steel – e.g. stainless steel, mild steel, high-strength steel, high/low-carbon steel or galvanised steel. Aluminium can also be used for certain components, which due to its lighter weight can help increase the fuel economy of a vehicle. Most steel car body panels will be around 0.6-0.8mm thick, while aluminium body panels generally have a thickness of 0.8-1.8mm.
Laser welding has been used in BIW manufacturing for decades, with Volvo being the first European car manufacturer to introduce it to the main line of its body shop in 1991. BMW also adopted the technology around the same time, using it joining roof parts on its sub-assembly line.
Lasers are used for cutting, welding, brazing and piercing applications in body-in-white manufacturing, when the frame of a road vehicle is assembled (Images: Gorodenkoff/Shutterstock).
BIW components can also be brazed using lasers, the difference being that welding involves melting the base material of two joining partners as they are held together, while brazing involves a filler metal being melted as it flows between the joining partners to create a bond. Laser brazing is often used for joints at the doors and rooflines of vehicles, creating a seamless, high-strength bond that can be readily painted over.
The majority of laser welding/brazing tasks in BIW manufacturing can be carried out by fibre lasers – favoured for their low operational costs. They can be used to create high quality welds between both similar and dissimilar materials – e.g. when welding steel to aluminium – while avoiding cold cracking, pores and spatter. In addition, fibre lasers can easily be integrated into the robotics of automotive production lines due to their beam being transportable via a flexible optical fibre down a robotic arm to a processing head.
Laser cutting, trimming and piercing has also long been a part of BIW manufacturing, with Austin Rover having installed a five-axis system to trim pre-production body panels all the way back in 1983.In addition, pillars, frames, antenna holes, bushings and holes for fixing exterior parts are all example parts that can be cut or pierced with lasers. Fibre lasers are also generally the favoured tool for such applications.
Sub-assemblies and vehicle interior
Lasers are equally used for the production of various sub-assembly and interior components in vehicle manufacturing.For example,laser welding can be used in the production of metal components such as gears, engine valves, brake callipers, tyre rims, seat frames, alternators, fuel injectors, filters, hasps, exhaust pipes, mufflers, bourdon tubes, airbag initiators, motor coil windings and various additional engine parts. Again, these would all typically be welded using fibre lasers. While most of these parts would be made from some form of steel or aluminium, in the sport and luxury car markets titanium is sometimes favoured due to its advantages of low density, high strength, and good corrosion/heat resistance. Fibre lasers can also be used to process parts made from carbon fibre reinforced polyetheretherketone (CFR-PEEK), which is commonly used in the manufacture of braking systems, engine and climate management systems, clutches, sensors, and running gears.
CO2 lasers have numerous applications in automotive manufacturing, as shown here. (Image: Luxinar).
In the cutting of fabrics for vehicle interiors, fibre lasers are outshone by their more traditional CO2 laser counterpart. This is because the larger wavelength (around 10µm) of CO2 lasers is better absorbed by non-metallic materials such as textiles, plastics, leathers and acrylics. They are used, for example, to trim excess material from fabric-covered dashboards and interior pillars. Other textile-based laser applications include the cutting of webbing for seat belts and fabric for airbags, as well as cutting and texturing real and synthetic leather for seats and trim, and carpet and mat cutting. In the case of airbags, the material they are made from is generally coated in silicone to help it retain the air when inflated, and this material can be laser cut before being stitched together. Since laser cutting is a non-contact process, there is only minimal handling of the fabric. This reduces the chances of any damage to the coating, which could adversely affect airbag performance.
CO2 lasers can also be used in automotive manufacturing for cutting and trimming plastic parts, such as interior and dashboard panels, pillars, bumpers, number plates, trims and electronic/light housings. Such parts are made from plastics including ABS, acrylic, HDPE, polycarbonate and polypropylene. For example, polycarbonate lamp fittings and plastic headlamp lenses can be trimmed with a CO2 laser to remove any waste plastic following injection moulding.
In addition, marking tyres with data matrix codes for traceability purposes is also a relatively new application of CO2 lasers. Lasers are also starting to be used in tyre prototyping to machine both tread and sidewall profiles into tyres. This could replace the need to manually carve tyres using hot knives, which is both a time-consuming and cost-intensive process with technical limits.
Battery and electric motor production for e-mobility
One of the more significant developments in automotive manufacturing in recent years is the ongoing switch to electric vehicles (EVs).
According to EV Volumes,a total of 10.5 million new battery EVs and plug-in hybrid EVs were delivered during 2022, a considerable increase of 55% compared to 2021. Statista goes as far to predict that by 2030, 26% of all new car sales worldwide will be electric vehicles. Such soaring demand has led to the automotive industry seeking out high-throughput processes and technologies for ramping up the production of batteries and electric motors for EVs.
The laser industry has answered this call to action tremendously, with numerous sources and systems having emerged specifically for this application field over the past decade.
In EV battery manufacturing alone, there are more than 30 applications for the laser. For example, lasers can be used to weld the foils and busbars of battery cells, seal battery cases, weld tabs to battery casings, and weld hairpins in electric motors. They can also be used to cut copper anode and aluminium cathode foils for batteries.
Lasers are now widely used for welding hairpins in the production of electric motors (Credit: Scansonic)
For companies such as Trumpf, e-mobility has consequently become a lucrative market, with it now making up approximately 40% of the revenue of the firm’s laser division. This demonstrates the significance of e-mobility as an opportunity for laser firms.
Among the new laser solutions that have emerged for this market in particular are blue (450nm) and green (515nm) lasers, which excel at processing the many copper components used within batteries and electric motors. This is because their visible wavelengths are absorbed particularly well by copper (65% absorption for blue, 40% for green), compared to the 5% absorption exhibited by infrared fibre lasers (1,070nm). Visible lasers are therefore able to avoid the challenges that come from using the higher fibre laser power required to overcome the reflectivity of the material, which can lead to weld defects such as voids and spatter that increase electrical resistivity. While fibre lasers can be equipped with technologies such as variable beam modes or wobble-welding heads to help mitigate these defects, visible lasers can achieve high-quality copper welds at lower power without needing to employ such measures.
Blue lasers have emerged in recent years as a solution for welding many of the copper components used in electric vehicles (Image: Nuburu)
Blue lasers are also ideal for welding dissimilar combinations of metals, such as copper and stainless steel or copper and aluminium. In the past, combinations like copper and stainless steel have proved tricky to weld with fibre lasers due to the creation of intermetallic phases that reduce the integrity of the welded joint. However, using blue lasers, the creation of these intermetallic phases can be minimised, or eliminated, in highly uniform welds. That’s not to say that fibre lasers can’t be used to weld such material combinations. Similar to copper welding, the challenges of dissimilar material welding can be mitigated to a degree using variable beam mode technologies.
Both the automotive and laser industries continue to evolve together, with each continuing to look for new applications of laser processing. For example, lasers are currently being adopted for the welding of bipolar plates in the production of hydrogen fuel cells, which are set to power the heavier vehicles of the future – where battery technology will fall short of delivering the driving ranges required. Additive manufacturing and cladding are also being increasingly explored, for example to optimise the topology and reduce the weight of structural components, or to coat brake discs in order to improve their durability.
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This article will be updated as Laser Systems Europe learns of new applications of laser materials processing in the automotive industry. If we haven’t included an application you are aware of above, feel free to let us know at: firstname.lastname@example.org.
 McKinsey Center for Future Mobility: Race 2050 – A Vision for the European Automotive Industry - January 2019
 EV Volumes - Global EV Sales for 2022
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