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Even though electric vehicles are becoming increasingly popular in the automotive industry, analysts predict that by 2025, more than two thirds of all vehicles sold will still be powered exclusively by combustion engines. Reason enough to consider how best to weld them.

Exhaust systems draw combustion gases from the engine and clean them. During this process they must withstand both high temperatures and corrosion. The demands placed on the individual components determine which material they should be made from.

The exhaust manifold presents a difficult welding challenge:  steel containing chrome meets a complex component geometry, tight radii, and precisely defined penetration.

Automated metal active gas welding (MAG) welding is the process most often used to join exhaust components. The exhaust manifold is particularly challenging for the welding process: the tight component radii force the robot to reduce the welding speed. Nevertheless, the amount of energy directed into the component must be kept to a minimum and the welding process must remain stable and reproducible.

Gap-bridging ability, reliable penetration, and speed – it is crucial that the welding process can meet these requirements when joining exhaust manifolds.

High Efficiency Electronics Open Up New Possibilities

Just like the exhaust manifold, other components also bring their own challenges. The type and thickness of the material used is based on the demands placed on the corresponding component group – for this reason, the welding process must also be adapted to suit the respective components. Fronius has a range of different process control variants for MAG welding that make it possible to consistently weld complex components. The high-performance electronics of modern power sources allow users to adapt the arc in a controlled manner and therefore achieve optimum results.

A CMT-welded flange seam on an exhaust system component.

The “Low Spatter Control” (LSC) mode is particularly suited to welding exhaust components. Based on a dip transfer arc, is both energy-efficient and spatter-free. This is achieved by the welding system precisely controlling the short circuit: The power source accurately detects the wire electrode approaching the weld pool and regulates the detachment of the droplet into the weld pool in such a way that it happens at a lower power. This means that the heat input into the component is low and almost no spatter is created. This is ideal for joining components with small wall thicknesses and variable joint geometries – such as on exhaust manifolds. In addition, LSC ensures high stability during the difficult reorientation of the welding torch and therefore high welding speeds.

Exhaust systems consist of complex individual components that place high demands on the joining technology.

A further process variant is “Pulse Multi Control”, also known as PMC. This modified pulsed arc is characterized by precisely regulated and low-spatter droplet detachment. PMC creates a powerful, stable arc, and, for example during out-of-position welding, offers high deposition rates and good controllability of the weld pool at the same time. Users can therefore avoid imperfections such as undercuts and weld in a stable and reproducible manner. This variant is particularly well suited to components that are subject to tolerances and have severe variations in wall thickness – conditions which apply to a number of exhaust components. Even in these situations, PMC ensures sufficient penetration and a gap-bridging ability. Automotive suppliers regularly use this process to weld exhaust manifolds. In practice, PMC enables the use of considerably higher welding speeds, thus increasing productivity.

Higher, Further – Thinner!

However, the challenges the automotive industry may face in the future could shift the focus onto other process variants. A significant trend in the industry is the development of increasingly lightweight vehicles. The lower weight reduces fuel consumption, while the material savings also reduce the manufacturing costs. This also affects the design of exhaust components. The temperature-resistant parent materials and filler metals used allow the components to be manufactured from increasingly thinner materials. Components with wall thicknesses of 0.8 millimetres could therefore become standard in the future. The CMT (Cold Metal Transfer) process is often used for this type of application. The process combines a regulated dip transfer arc with a wire electrode that moves forwards and backwards. The result is a particularly low heat input and an incredibly stable welding process, which even allows users to achieve optimal results when welding very thin components.

Fronius UK

Fronius UK, a subsidiary of Fronius International, provides the UK welding market with solutions for MIG/MAG, TIG, electrode, laser, plasma and resistance spot welding and automation. Its new state-of-the-art facility in Milton Keynes extends over 30,000m2 and houses the Tech Support team, the Repair Center, a warehouse and a training area and epitomises the importance of being able to deliver a first-class service to customers.

Fronius UK, a subsidiary of Fronius International, provides the UK welding market with solutions for MIG/MAG, TIG, electrode, laser, plasma and resistance spot welding and automation. Its new state-of-the-art facility in Milton Keynes extends over 30,000m2 and houses the Tech Support team, the Repair Center, a warehouse and a training area and epitomises the importance of being able to deliver a first-class service to customers.

Sales and service teams, both at head office and regionally, ensure that customers are supported as quickly as possible on their own premises. In addition, customers benefit from services such as calibration, a warranty extension and a maintenance contract.

For decades, Fronius has made significant contributions to advances in welding technology. The company is still in family ownership and its welding technology division is now one of the world’s technology leaders in the arc welding market segment. It is also the market leader in Europe.

Welding Technology is one of three Fronius divisions. Since the 1940s, Fronius has been creating technologies and solutions for monitoring and controlling energy in battery-charging systems, and since 1992 the same in solar electronics. The mains-connected inverter, the unique Fronius Service Partner programme and products for monitoring photovoltaic systems make Fronius one of the leading suppliers in the field of solar electronics.

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