Chain sprockets printed in 3D make e-bikes whisper

• What was needed: plastic pinion
• Manufacturing process: selective laser sintering
• Requirements: high wear resistance, good sliding properties, high service life
• Material: iglidur® i3
• Industry: Bicycle industry
• Success through cooperation: fast configuration of the component in the online 3D printing service, quieter running noise than with metal

The application at a glance:
E-bikes are becoming ever lighter and extremely quiet. When riding, you hardly notice any motor noise at all. However, resourceful inventors like Lars Hartmann from Reichshof are not satisfied with this. The excessive background noise in the bicycle chain was a thorn in his side. A metal sprocket acted as a guide pulley on the chain to prevent it from colliding with the frame, but caused immense running noises. In his search for a remedy, he remembered what igus had to offer®, which he learnt about at a trade show: The 3D printing service, which enables customised components to be produced cost-effectively in a 3D printer.

The standard metal chain wheel on the electric bike made a very loud running noise. The chain wheel was the deflection pulley for the chain so that it did not come into contact with the frame. The friction noises made the e-bike feel like a tractor. Accordingly, Lars Hartmann set out to find a material that had the same running properties as the metal sprocket, but was significantly quieter. Other requirements for the material were good sliding properties and a long service life, as well as high wear resistance in combination with metal.

As part of his work for VMA Getzmann GmbH, a manufacturer of stirring, dispersing and fine grinding systems, machine parts were tested that were manufactured using the 3D printing service from igus®. The results were so good that Lars Hartmann also considered the printed parts for his e-bike. The perfect solution for the hobbyist: "The standard metal sprocket made a lot of running noise. We drew it and had it printed at igus® from iglidur® i3. The process was quick and easy. We used the 3D printing service to upload the relevant data, selected the material and ordered the quantity." The sprocket has been in use in two wheels for several months - and the noise has been significantly minimised, says Hartmann happily.

The iglidur® i3 material used is naturally also suitable for industrial and series use. It impresses with its good wear values and high strength and is processed using selective laser sintering (SLS).

For particularly high wear resistance requirements and a long service life, igus® has also developed the material iglidur® i6. The high-performance plastic beats milled gears made from common materials such as POM and PBT in the test. A worm wheel with a torque of 5 Nm and 12 rpm was tested. Even after one million cycles (test cancellation), the gear made of the laser sintering material iglidur® i6 showed only slight wear and was still fully functional. This allowed it to clearly outperform milled gears - gears made of POM showed total wear after just 621,000 cycles; milled gears made of PBT broke after just 155,000 cycles. Also in the test: a gear made from the laser-sintered material PA12. However, due to the high coefficient of friction, this failed after just 521 cycles.

At the same time, designers also benefit from the igus® Zahnradkonfigurator. This allows customised sprockets or chain wheels to be configured, even in special dimensions. In just a few steps, the user only needs to enter the data for their gear (such as tooth module, number of teeth, width and inner diameter). A 3D model is then automatically created, which can be exported as a STEP file. By uploading the file to the igus® 3D printing service, the configured gear can be ordered directly from the extremely durable SLS material iglidur® i6 for gears. With a click of the mouse, the user can order their gear with no minimum order quantity or request a quote. The customised part is ready for dispatch within just three days.