The InnoForm project pursued the goal of establishing alternative mould materials, in particular made of ceramics or hard composites, for the non-isothermal blanking of glass components. One of the various areas of application of non-isothermal blanking is the serial production of optical components made of glass, for example to enable the production of inexpensive LED lighting optics, which require particularly good resistance to extreme temperatures and UV radiation. In this segment, the service life of the tools is a critical success factor because it has a direct impact on the unit costs of the stamped glass components. As with all replicative processes, the shape of the die and especially the materials used are of crucial importance.
For non-isothermal blanking, only steel dies have been used so far. However, the limited hardness, strength, temperature resistance and chemical resistance of the steel lead to high wear, to a large repolishing effort and ultimately to the total failure of the die after a comparatively short life cycle.
As part of the project, various ceramics and refractory materials were examined with regard to their suitability for non-isothermal blanking. In this case, alongside considerations for the pure stamping process, also the upstream die construction and the design of ceramic tool systems were specifically considered. A final evaluation of promising material approaches was carried out through stamping tests on a technological scale as well as in small batches, each with 5000 pressing cycles. By employing the best material variants, it was not only possible to achieve a service life that was many times longer than that of the steel dies, but also a significantly increased blank accuracy of P-V = 2 μm with a repeatable accuracy of ± 0.3 μm.
The research work described was funded through the Central Innovation Program for SMEs (ZIM), run by the German Federal Ministry of Economics and Technology (BMWi).