Open Access

Steels for plastic injection moulds are available in different alloy compositions. Mechanical properties, such as wear resistance and hardness, are the most important properties of these steels. Corrosion resistance of these steels is also an important property, which is why there are high-alloy steel compositions. The cooling and temperature control systems for moulds have different types of fluid circuits. There are open and closed systems, which has a direct influence on the oxygen content in the fluid. There are also different types of water, such as hard and soft water, and different types of additives, for example biocides or corrosion inhibitors. The aim of this work is to investigate the corrosion behaviour of various typical plastic mould steels under high and low oxygen conditions. With these results, a mould tempering device will be developed that controls the oxygen content in a closed water-based liquid system. If this is successful, chemical additives can be dispensed with and good corrosion behaviour can be achieved, even for low and unalloyed steels. Steels with different chromium contents typical for this application were selected for the tests. Heat treatment was carried out in a typical way for these steels. Corrosion behaviour was measured by open circuit and potentiodynamic measurements in soft water at 50°C. Oxygen-free and oxygen-saturated conditions were investigated.

In this paper, the mechanical subsystem of a proportional solenoid excited by a dither signal is considered. The objective is to find a suitable friction model that reflects the characteristic mechanical properties of the dynamic system. Several different friction models from the literature are compared. The friction models are evaluated with respect to their accuracy as well as their practical identifiability, the latter being quantified based on the Fisher information matrix.