50 years of pioneer and trendsetter

Friction and pressure – the principle of friction welding is simple and ingenious and has developed into one of the safest and most economical joining processes in modern production technology over the past few decades, even in mass production, thanks to its many possibilities and impressive advantages. Klaus Raiser GmbH & Co KG from Eberdingen has played a major role in this. As a pioneer and trendsetter, the company has been constantly driving the development of friction welding technology for 50 years.

Friction welding is a welding process from the group of pressure welding, was developed in the 1950s and made usable for industrial applications – the principle: the two workpieces to be joined are moved towards each other. One joining part rotates extremely quickly around its own axis (rotational friction welding) or swings back and forth (linear friction welding), while the other remains stationary. When the two workpieces meet, the friction generates enormous heat and chemical bridges form on the contact surfaces. As soon as these have reached their highest possible density, the movement is stopped and at the same time the pressing pressure is significantly increased. The parts are then welded together. The characteristic material bulge at the contact point can be quickly and easily removed by subsequent turning. Today, friction welding is one of the most reliable joining processes for modern mass production. It is firmly established in many industrial production areas and friction welding joints guarantee a high and easily reproducible quality standard. A particular advantage is that friction welding enables a wide variety of materials to be joined, as the joint is not formed via the molten phase. Even more interesting than the possibilities for joining different steel materials is the combination of different non-ferrous materials with each other or with steel. Examples from an almost unlimited list of applications include steel-copper and aluminum-copper joints for die-cast pistons and the electronics industry. Friction welding has many advantages: Cycle times of just a few seconds and very high quality weld seams. For example, the joint seam in this forged structure usually has a higher strength than the base material itself due to the full welding. The process is so reliable and reproducible that virtually no rejects are produced.

Pioneer and trendsetter in contract welding and mechanical engineering

In 1969, Klaus Raiser founded his company as a supplier for welded constructions in Eberdingen in the Ludwigsburg district. The founder then quickly discovered friction welding, which had been relatively unknown until then, and recognized its many advantages and possibilities. Friction welding technology in all its many facets has been the company’s core business since 1974 and has paved the way for Raiser to evolve from a craft business into a globally sought-after technology company that is constantly developing and advancing this powerful process. Its customers include machine and plant manufacturers as well as numerous automotive manufacturers and suppliers of all sizes. The company has grown steadily and successfully. In 2007, for example, Raiser expanded its production area by 3,700 m² with the construction of a new administration building and a new production hall in nearby Hochdorf. The processes of friction welding, mechanical processing, welded constructions, robot welding, annealing and mechanical engineering are thus once again carried out at the same location. Today, with five friction welding systems and a capacity of <5 to 1250 KN upsetting force, Raiser is one of the largest contract friction welding companies in Germany. As a modern service company, Raiser goes far beyond actual contract manufacturing, producing ready-to-install components and offering complete pre- and post-processing from a single source. In addition to extensive capacities in the field of rotary friction welding and linear friction welding, Raiser also offers friction stir welding as a service. Raiser uses the numerical simulation method of the finite element method (FEM) for both machine and process development. The process simulation allows precise analysis of the friction welding process before, during and after welding. A precise simulation can be achieved through constant comparison with real process data. State-of-the-art testing and monitoring methods ensure that all required quality standards are met. Dr. Elmar Raiser, son of the founder and current Managing Director of Klaus Raiser GmbH & Co KG, who joined the company in 1994 after studying mechanical engineering and completing his doctorate and took over his father’s “sceptre” in 2007: “Advising our customers on the optimization of joining geometries and material selection is a prerequisite for customer-specific success. Our involvement in national and international specialist committees and research projects ensures that the latest findings are always incorporated into production. In addition, our ‘Raiser Innovation Award for Friction Welding Technology’, which has been awarded every two years since 2011, sustainably promotes research and development in the field of friction welding. A particular aim of the award is to support young talents from science and industry and to encourage them to present their innovative new and further developments in all areas of friction welding.”

Sophisticated friction welding machine concept

Raiser has incorporated its decades of experience with the friction welding process into the development and construction of friction welding machines. Important chapters in the company’s history include Raiser Engineering GmbH & Co. KG, founded in 2012 for the production of special machines. This provides a complete service from planning, CAD design, simulation and optimization to construction and assembly – all from a single source. In 2021, Raiser takes over the friction welding division of Symacon Maschinenbau GmbH, thereby expanding its product portfolio in the field of friction welding machines. This expansion of expertise makes Raiser a full-service provider for friction welding – from process development and contract manufacturing in small and large series to the finished machine. Today, Raiser’s machine portfolio includes machines with an axial force of 5 to 3,000 KN. This ranges from standard machines to special systems tailored to customer requirements – as a stand-alone unit or as a production unit integrated into a production workflow. Elmar Raiser: “Our extensive experience and know-how in the field of friction welding technology are consistently incorporated into the development of friction welding machines. Passing on decades of experience gives our customers a head start in the use of friction welding technology. For both linear and rotary friction welding machines, the focus is on optimally adapting the machine to the component to be produced and to individual customer requirements. Our aim is to manufacture the machine optimized for the respective application. We make use of a large modular system of standard components. The modern machine concept, which is tailored to each individual case, enables the friction welding machine to be integrated into upstream and downstream production processes.” The use of proven and standardized components ensures high machine availability and a long service life. Raiser consistently relies on servo-electric feed drives to apply the axial process forces. In addition to the many process-related advantages such as length accuracy, concentricity and reproducibility, this also results in a large energy-saving potential compared to classic hydraulic friction welding machines. In addition to automation concepts for parts feed and removal as well as pure process technology, the machine layouts always focus on ease of operation, ease of service and maintenance as well as quick changeover options. Raiser also places great emphasis on the removal of the welding bead created during friction welding. A wide variety of removal methods such as turning, milling and punching are available for both the outer and, if necessary, the inner bead. Modern CNC turning and milling units enable precise pre- and post-processing of the parts immediately before or after the friction welding process.

“The special feature of our friction welding machines is that the spindle (rotor) applies the upsetting force in an axial direction, unlike the friction welding machines of most market competitors. This provides more space and enables a greater variety of clamping technology to be installed,” explains Elmar Raiser. “We also generate the feed force via a servo-electric drive. This brings further advantages, such as lower noise emissions and better energy efficiency. In the best case scenario, the hydraulic unit is no longer required or can be designed smaller, as only the clamping movements are controlled hydraulically.” One example of innovative Raiser mechanical engineering is the HFR 1.000 friction welding machine, with which Raiser offers a universal solution for components with a friction surface of up to 8,000 mm² and an upsetting force of 1,000 KN. Thanks to the modular system, the HRF 1,000 can be upgraded to an HRF 1,500 in a higher expansion stage. The modular design also covers a wide range of components that can even replace special machines. With the upsetting force and high torque of the HRF 1000, new markets can be opened up for components for which the friction welding process previously seemed unsuitable. The machine concept offers various expansion stages: There are options between a standalone machine with manual loading; a closed production cell with various automation solutions or a fully automated system that can be integrated into the production chain. Raiser also attaches particular importance to component-focused clamping systems. This is because very complex and sometimes sensitive components often have to be clamped on the stator side. For this reason, Raiser can also provide users with the development and design of a component-matched workpiece clamping system on request. In addition, process automation reliably protects people, machines and the environment. Elmar Raiser: “Our 70 motivated employees are a cornerstone of our success. Together with them, we are constantly developing and finding new ways to master our customers’ challenges even better. For us, solving a problem with special material joints is not just about supplying good friction welding technology. It begins with the analysis and consultation with the customer and ends with the customized friction welding solution – in the contract sector as well as in plant engineering. The bottom line is that our friction welding machines meet both current and future requirements in terms of quality, performance, efficiency and flexibility.” Web: www.raiser.de