The cold casting process allows the integration of pipes and lines.
Near-net-shape casting due to Granitan technology
The casting mold is carefully assembled.
For half a century, machine bases made of Granitan have formed the foundation for reliable STUDER precision in cylindrical grinding.
There is a focused working atmosphere as employees in overalls carefully prepare the mold: they install pipes, cables, plates, threaded dowels, and rails. Then a powerful machine pours in the viscous mixture, which is mixed according to a closely guarded recipe, with various sizes of aggregate. This is a mineral casting mixture that will harden into a high-performance machine base in less than a day. For 50 years, this composite material, Granitan, has been the foundation for the accuracy and reliability of STUDER cylindrical grinding machines.
"It was a groundbreaking innovation in machine tool manufacturing when the RA5, the first series-produced cylindrical grinding machine with a Granitan machine base, was launched in 1976," said Lennard Vorwerk-Handing, Development Engineer at STUDER.
The iron-based gray cast iron that was commonly used until then could only be formed at very high temperatures and required extensive reworking. Granitan, on the other hand, can be shaped at room temperature, similar to concrete. In fact, some manufacturers had previously experimented with cement-based machine bases.
"Cement-bound concretes exhibit significantly greater shrinkage and tend to absorb moisture. This meant that the required absolute long-term stability could not be achieved," explained Vorwerk-Handing.
The development team of experts from STUDER and several partner organizations came up with a novel idea: instead of cement, epoxy resin was used as a two-component binder that is stable in the long term and does not absorb water. The mineral casting material, christened Granitan, was suitable for precision parts and could also be molded quickly and efficiently in-house. Without time-consuming post-processing, it can be used to manufacture near-net-shape machine components and integrate structures and lines directly into the mold in the cold casting process. Compared to gray cast iron, the more energy-efficient manufacturing process also has a positive effect on the sustainability balance of the entire machine.
"Granitan also revolutionized precision in the grinding process," explained Vorwerk-Handing. "One of its outstanding advantages is its damping behavior, which is about 15x better than that of gray cast iron. Vibrations are quickly absorbed by the material. This is because the contact surfaces between the rock grains and the binder matrix efficiently destroys the vibration energy. This is particularly important in precision cylindrical grinding, where even the smallest vibrations can lead to surface marks. Due to Granitan, STUDER customers achieve higher product quality and can operate the precision cylindrical grinding machines without special foundations."
The outstanding thermal properties of Granitan are no less important. "Compared to gray cast iron, it can absorb twice as much heat energy before the temperature changes by 1 °C," noted a company spokesperson. "Heat is also transferred up to 13x more slowly in the machine base. At the same time, it has a similar expansion behavior to steel or iron, which means that no stresses occur at the coupling points to metal machine parts. The advantages for customers are enormous: Granitan is robust against the temperature fluctuations that are common in everyday production in factory halls and enables reproducible grinding precision, even in rooms that are not precisely air-conditioned."
Modern STUDER cylindrical grinding machines are high-tech systems with extensive digital capabilities, sensitive sensor technology, and automation and networking features. However, Granitan is still the machine base that provides the precision and reliability for which the traditional Swiss company with over 113 years of history is known. The reason for this is continuous optimization and further development: Today's Granitan is the result of intensive research and development activities in material composition and manufacturing technology. Since 2009, STUDER has been manufacturing its Granitan machine bases as part of a joint venture with Schneeberger in a highly specialized production facility in Cheb, Czech Republic-still using its own STUDER recipe and process control.
In addition, there are now Granitan recipes for specific applications: the base mixture S103 forms the solid, highly damping machine base, while fine-grained special mixtures are used for casting precision components. Granitan technology thus enables the high-precision manufacture of StuderGuide guideways with micrometer accuracy in the company's own molding shop. The enormous design freedom offered by the liquid material during initial forming results in highly compact and maintenance-friendly machine designs that would not be possible with other manufacturing methods.
"Five decades after its market launch, Granitan has become synonymous with a stable machine base that continues to set standards in the industry today," said the spokesperson. "Combined, the advantages for customers lead to higher workpiece quality, more reliable production, and longer service life. In view of the growing demands for precision, sustainability, and flexibility, it therefore remains an indispensable basis in machining, whether for machine tools, aerospace, electronics, or medical technology."
To ensure the continued success of its customers, STUDER is consistently investing in optimizations and new features. One prospect for the future, for example, is the potential integration of sensor technology and electronics directly into the machine base, which is possible due to the cold casting process.
"Granitan is more than just a material; it is a technology kit and a platform for future innovations," said Rolf Grossenbacher, Sales Manager Far East, adding: "Our high-performance material Granitan will continue to help customers perform grinding at the cutting edge of technological feasibility with STUDER machines."
Authored by UNITED MACHINING SOLUTIONS
For more information contact:
UNITED GRINDING
2100 UNITED GRINDING Blvd.
Miamisburg, OH 45342
937-859-1975
info@grinding.com
www.grinding.com