Martin Klimach (left) and Alexander Brechtel are the founders of Carbon-Drive. They produce spindle motors made from carbon fibers. These are lighter and more stable than steel spindles, thus saving energy and raw materials while at the same time producing much more precisely and cost-effectively. Anja Störiko.
Next year they will be celebrating their tenth anniversary. They were one of the first teams from Darmstadt to receive EXIST funding from the federal government. Carbon-Drive is now supplying its first customers.
“Motor spindles are the premier class of electric motors,” says Martin Klimach, explaining their product: they make tools rotate by directly converting electrical energy into mechanical work. Motor spindles essentially consist of a housing and a shaft to which a grinding or drilling tool can be connected at the front. The spindle contains the shaft, magnets and motor. “In our case, it is made of carbon and is therefore half as heavy,” says Klimach, describing a key advantage. He points to a spindle that is currently being used for grinding.
A carbon motor spindle, on which a grinding wheel is mounted here. © Anja Störiko
Powerful and low-vibration drilling, milling and grinding
Carbon fiber materials – known as carbon for short – are very stiff but light at the same time. The machines made from it are therefore stable, energy-efficient and quiet. Further back in the workshop, a machine winds the carbon fibers into a spindle: thin carbon threads are immersed in a bath of epoxy resin before being wound around a steel core in a stable cross pattern. In this way, plastic and carbon fibers bond together to form a very rigid material – “similar to reinforced concrete,” explains Klimach. It is also highly precise in the event of temperature fluctuations and therefore does not have to be monitored and compensated for like steel. They have optimized the structure of the various layers at Carbon-Drive. “Nowadays, this is easy and inexpensive with appropriate computer calculations,” says co-founder Alexander Brechtel. This development has already enabled carbon fiber to make the leap to mass application in bicycles, cars, skis and surfboards – and now also for engines.
The carbon fibers are dipped in epoxy resin and wrapped around the steel core to create an extremely stable spindle. © Anja Störiko
Founding at the right time
“At the time we founded the company, carbon was available at competitive prices, there was a lot of experience at Helmut Schürmann’s institute, a major manufacturer showed interest – and Martin’s doctorate was complete,” summarizes Brechtel. Klimach had studied in Darmstadt and came back to Prof. Schürmann’s Institute for Lightweight Construction, “the carbon luminary”, after a stay abroad. There he designed a carbon shaft as part of his doctorate. In 2012, three years of successful tinkering resulted in an application to the then still relatively new start-up funding program EXIST, which supports the transfer of research from the university. “HIGHEST helped, but was still in the orientation phase,” Klimach smiles. The result was four years of funding for six employees. Industrial engineer Brechtel – “we met at university sports” – joined Klimach’s team for his Master’s thesis.
They were founded in June 2016. A research project with the market leader for motor spindles showed the possibilities for their carbon spindles. For the time being, however, much remained the same: The funds from the federal government financed the employees who built the first carbon motor spindle at the university. “The hard cut came in the second phase of the start-up funding: we had to manage everything ourselves, really make ourselves independent,” says Klimach.
Since 2018, they have been tenants in a factory building on the outskirts of Weiterstadt, together with other start-ups. “We exchange ideas, help each other, think outside the box,” says Klimach, describing the constructive collaboration.
A spindle drill mills computer-controlled holes in a spindle housing. Anja Störiko
New machines – a tricky business in Germany
When EXIST ended in mid-2019, the first customers commissioned certain spindles, such as research institutes. But development took time, so Carbon-Drive had to finance itself with services and simple products. “There were seriously interested industrial customers at trade fairs – especially after we won an innovation award,” reports Brechtel. But in most cases nothing came of it – “when they realized: oops, this is a very small young company”. This is because the industry is very conservative. Machines are at the heart of every production process, so nobody takes any risks.
Following initial production for research institutes, Carbon-Drive delivered the first spindle to a Swiss machine tool manufacturer last year. It is now going into series production. To do this, they have purchased a new machine that can work in five axis directions under computer control.
“But that also takes time,” says Brechtel. After all, 40 units with this equipment are now to be built and sold every year. They will then have to prove themselves in everyday use by customers. Carbon-Drive has proven that its carbon spindles are up to 20 percent more productive. But they have not yet been able to achieve a correspondingly higher price. “We imagined it would be easier,” admits Klimach, ”especially as even fewer machines are being ordered during the economic downturn.” The German market is difficult. They now have a joint venture in China. They manufacture there, but control production electronically from Weiterstadt.
Role model Rennauto
Over the years, Carbon-Drive’s growth has been organic and possible without investor support – cross-financed by research projects, services and small orders. “A ride on the razor’s edge,” admits Brechtel. “But at some point in racing, carbon cars also became established – there’s a reason for that.” And her arguments in favor of carbon motor spindles sound convincing: Lighter. More precise. More energy efficient. More productive. Faster. Less waste. That’s why their logo is the Colibri, the “Kohle-bri”, as Brechtel says with a wink: light, fast and precise.
Carbon-Drive now has one full-time employee. They also have two patents of their own. They reduced their initially extreme working hours after the birth of their children. “But it always feels like you’re doing too little,” Klimach points out. But they are self-determined and appreciate that. “I enjoy coming here every day,” adds Brechtel. “Carbon will also prevail in motor spindles,” Klimach is certain. “The question is whether we will be there,” says Brechtel – without really doubting it.
This is how Carbon-Drive tests the efficiency of its spindle motors: the deeper the groove without deviations, the more precise the spindle. The Carbon spindle is always clearly ahead. © Anja Störiko