November 2018At 60 km/h, the remote-controlled car of students at the Eugen Reintjes Vocational School in Hamelin is as fast as a lion. Its powertrain includes wear-resistant gears made of high-performance plastic, which were cost-effectively produced using a 3D printer. The e-flitzer will be competing in the JET Challenge race, which is being organized by the Association of German Engineers (VDI) as part of IdeenExpo 2019 in Hanover, Germany.
E-mobility is one of the hottest topics of the future. For Germany to play a leading role, students need to be inspired about science and technology careers today. Of these, the Association of German Engineers (VDI). The Hanover University of Applied Sciences and Arts (HSH) convinces. Since 2007, they have been running the "JeT Challenge" competition at the Ideen-Expo in Hanover, an event that has since become Europe's largest youth event for science and technology.
In 2019, visitors to the HSH stand will be able to marvel at a highlight: a 20-meter-long racetrack, carpeted, edged with wooden beams and padded with foam. The railroad is the venue of the so-called JET-Challenge. JET, which stands for "Youth Discovers Technology. But not just any technology. Pupils from all over Lower Saxony to get excited about e-mobility. Around 25 teams take on the task of building an electrically powered and remote-controlled car on a scale of 1:10. In the competition, cars compete against each other. To win, however, the car must not only be fast, but also energy efficient – one of the key characteristics that also determines the success of an electric car in the adult world.
Strict rules: Only 50 euros are available for car tuning
The team with the most money has an advantage? No, because budgets are limited. Only 50 euros are available for the students to buy a commercially available remote-controlled car – also called a Remote Control (RC) Car- into an efficiency machine. The students of secondary levels I and II learn the theoretical basics in physics and technology classes. This includes the one-and-done of the gear, electric motor and battery technology categories. The students then disassemble the car to reassemble it as a three-wheeled version. The team from the Eugen Reintjes vocational school in Hamelin, Lower Saxony, uses a gear system with modified gears. Sounds simple. But it is a logistic challenge. For where can you get gears at low cost whose dimensions can be freely determined and which are also wear-resistant and reliable? Finally, the budget belt is tightly buckled.
Students save money with 3D printing service
The vocational students found what they were looking for at igus. The gears can be configured via an online configurator. With a few mouse clicks the students determine among other things size and number of teeth. Alternatively, they can upload a digital design plan as a computer aided design (CAD) file. The production will then be done by a 3D printer using the so-called selective laser sintering (SLS) process. A coater spreads an ultra-thin layer of a plastic powder on a building platform. A laser fuses the powder wherever the gear is to be created. Then the platform lowers by one layer thickness and the process starts all over again. In a few hours, layer by layer, the gears are created from wear and tear. Abrasion-resistant high-performance plastics for the transmission of the racing car.
The SLS process is cost-saving. Because neither special tools nor injection molding are required. A process that is enjoying increasing popularity among young inventors with low budgets and professional prototyping alike. "Due to the very high demand for wear-resistant special solutions via the 3D printing service, we have now increased our capacity by 200% with new SLS printers," explains Tom Krause, Head of Additive Manufacturing at igus.
High-performance plastic makes race cars robust
To ensure that wear-resistant gears made of high-performance plastic are also wear-resistant, igus has developed a high-performance plastic called iglidur i6 in the laboratory as a printing material for the 3D printer. Lab tests prove: The plastic is significantly more robust than classic polyoxymetylene (POM). In a test, engineers ran gears at 12 rpm and loaded them with 5 Nm. A milled gear made of POM was ready for use after 321.000 revolutions worn out and after 621.000 broken. The car would instantly break down in the race. The GAU. The 3D-printed gear made of iglidur i6, on the other hand, performed significantly better. Even after one million revolutions, the component was still fully functional and wear was hardly measurable. So the students can trust in high fail-safety.
Wear-resistant gears made of high-performance plastic have already passed their baptism of fire
Gear wheels with 51 teeth (module 0.6) made of iglidur i6 are used in the transmission of the race cars from Hamelin. SLS components from have already passed their baptism of fire.
"Yesterday, I fitted our test vehicle with the gear from Cologne and burned up a battery charge; the installation went smoothly, as planned," explains Jürgen Molsbach, a teacher at the Eugen Reintjes school. The component works great. "Now, even with small wheels, the vehicle can reach the top speed of up to 60 km/h and still be driven in an energy-efficient manner."
Whether this speed is enough for the victory will be shown at the IdeenExpo, which will be held from 15. Until 23. June 2019 will be held in Hanover. Self-confidence is present with the pupils in any case. At the JET Challenge 2018, they brought the trophy to Hamelin. "The race for the best e-mobile is fun for young people," says Molsbach.