Hardened cam elements save petrol
Researchers at the Fraunhofer IWS Dresden developed a cam element laser hardening procedure for a new drive concept for a German car manufacturer. The new approach enables switching off two of four cylinders under partial load on demand. This provides a significant reduction of fuel- and CO2 emissions. Fraunhofer IWS developments aimed at hardening the cam element at high-stress points, which, in turn, increased wear resistance and lifespan.
The complex component contours to be hardened raise particular challenges. The Fraunhofer IWS has used high-power diode lasers, which have in general been shown to be efficient laser hardening tools in terms of the price-performance ratio, beam quality and the variety of available optical systems. The decisive advantage of the laser is that the component is less distorted, and, as a result, the post-processing work is dramatically reduced. To harden the cam contours as required, the researchers used the dynamical "Lassy" beam shaping system engineered at the Fraunhofer IWS. The Lassy system sets the intensity distribution according to the process requirements and makes possible very short cycle times. Since hardening demands precise temperature control, an "E-MAqS" infrared camera was combined with a "LompocPro" temperature control system. The latter responsibly monitors the process data generated by the system and component quality. Defective components are thus automatically eliminated from the system. Unlike conventional batch processes, the cam elements are now produced in line. This way, less energy is input into the component than in conventional hardening techniques.
The Fraunhofer IWS task included both process and technology design, based on which the concept for the serial production system was drafted. The scientists also developed the system hardware, and they manufactured the assembly stages. Afterwards, they took the processes into operation, and led as well as supported them in serial production. The engineers connected the components with the equipment control and established the respective interfaces; they also developed and installed the logical procedures together with the equipment supplier. They customized all process parameters, such as temperature, feed rate and laser positions for the serial hardware. In the development, the research team also contributed to material selection and supported the automotive manufacturers in design to tailor the components and the manufacturing sequences optimally for laser hardening.