In recent years, a confluence of trends in industrial, technology and biomedical design has sparked renewed interest in precision machining – the manufacturing of highly accurate parts that bring these designs to life – and this direction in new product design is revitalizing interest in a long-established production process: Swiss machining.
Swiss machines, or Swiss lathes, achieve precision on very small parts by minimizing the various forces generated by turning or grinding as the workpiece passes through sliding headstocks and guide bushings.
Now, developers at Tschudin AG have introduced design elements that further improve the machine’s precision: the Tschudin Cube 350 is said to be the world’s first grinding machine with perfect heat transfer.
“We have been working consistently for 30 years to minimize heat transfer in our machines,” explains Urs Tschudin. “With our all-new carbon grinding and alignment spindle, we have now completed the final piece of the puzzle.”
“With this spindle concept, we position ourselves as innovators and offer our customers new dimensions of precision and removal rates,” he added. By minimizing the thermal cycles in the grinding sequence, the developers claimed, a consistently high level of production precision is guaranteed.
“Even if the machine has been down for the weekend, we can still produce immediately with dimensional deviations of up to 1 µm,” says Tschudin. And in such situations, multi-track grinding also ensures that all parts are produced with exact dimensions. Thermal displacements are prevented, so the grinding and adjusting wheels remain parallel.
To underline, this means that the new Cube 350 will operate reliably unattended for very long sequences, even on unmanned shifts.
“High grinding quality with complete coverage of the grinding gap is already a quality characteristic of our machines. With the carbon spindle we are optimizing this even further and pushing it to the limit,” Chudin emphasized.
Decades of development
Swiss executives maintained that the introduction of carbon fiber spindles was the culmination of decades of development: Tschudin’s machines have used linear motors for 30 years, and more than 25 years ago, machine beds made from solid natural granite were adopted, which retain very little heat due to their size and inertia.
The slide of the grinding spindle was then designed as a block of granite, with a vertical stop surface on the spindle to further reduce heat transfer.
Swiss machine manufacturer Tschudin says its carbon fiber spindle, for which it is currently filing a patent application, reduces heat transfer to an “absolute minimum.” The new spindle was developed in collaboration with Carbon-Drive GmbH and has been tested and refined for over six months with “promising results.”
“How a material reacts to heat has a major impact on precision manufacturing. Carbon fiber is particularly heat-resistant,” explains Nicholas Ernst, design leader at Tschudin AG.
“The carbon spindle therefore prevents the machine from undergoing thermal expansion,” Ernst continues. “The carbon spindle has high dimensional stability and high bending stiffness, which means it can run at higher feed rates and, as a result, better cutting performance. In a series of tests, the carbon spindle proved to be 10 to 20 percent more effective than a steel spindle.”
Carbon-Drive GmbH, Weiterstadt, Germany, is Tschudin’s exclusive development and design partner for carbon fiber spindles in the field of centerless grinding. The German company was founded based on research carried out at the Technical University Darmstadt.
“Carbon fibre spindles offer a variety of benefits, first and foremost being minimal thermal expansion,” explains co-founder and managing director Dr Martin Klimack. “Depending on the fibre type and fibre orientation, we can manufacture carbon fibre spindles with a range of properties to suit our customers’ process requirements.”
Urs Tschudin and Martin Klimach met in 2019 when Carbon-Drive GmbH was working on the development of a carbon fiber milling spindle. The idea of using a carbon fiber spindle for grinding operations was a common goal, and the prototype spindle was ready at the end of 2023.
Better than steel
“The entire development process is complex. Existing manufacturers know steel (spindles) very well and all their processes are designed for steel,” Ernst points out. “But we are convinced that a carbon fibre spindle will offer significant added value due to its physical properties and also be attractively priced.”
According to Urs Tschudin, the Cube 350 grinding system with carbon fiber spindle should be attractive to manufacturers with the highest demands in terms of quality and precision: “The more precisely the parts have to be manufactured, the more attractive a grinding machine with optimal heat transfer becomes, since it can provide real added value here thanks to its dimensional stability and increased drive power,” Tschudin elaborated.
The Tschudin Cube 350 is a centerless grinding machine designed to produce parts up to 20 mm in diameter and plunge grind parts up to 150 mm in length. It also excels in deep grinding of parts. It can be equipped with various automatic loading options and pre- and/or post-process gauges.
With a base of just 2.60 x 1.70 metres, the Cube 350 compact centreless grinding machine offers manufacturers a small footprint for high-precision machining. In production, the machine offers high productivity thanks to extremely short changeover times: according to the developers, changing between grinding and adjusting wheels takes just six minutes.
The machine can be operated from either the left or right side, which makes its ergonomic design appealing.
According to Tschudin AG, the standard version of the Cube 350 will continue to be equipped with a steel spindle, with a carbon spindle available as an option.
