Replacement gear from the 3D printer - small change, great effect

What was needed: Replacement gear for a tractor engine
Manufacturing process: selective laser sintering
Requirements: high wear resistance, good sliding properties, good mechanical characteristics
Material: iglidur® i3
Industry: Commercial vehicles
Success through cooperation: 10 times more favourable manufacturing costs than with conventional manufacturing processes, complex component manufactured in one piece, improved abrasion resistance

The application at a glance:
The igus® cleaning team uses a tractor for its work, such as spreading and transport work. After some time, the gear used as a starter for the tractor's engine was so worn that the tractor could no longer start. The manufacturer was unable to provide a replacement and so the tractor remained out of service. After about a year without a tractor, it was to be scrapped. However, the igus® 3D printing team arrived shortly beforehand and was able to reproduce the worn and broken gear and print it in just a few hours. The tractor is now running reliably again thanks to the gear made of iglidur® i3, which has significantly better sliding properties and higher wear resistance than the previously installed gear made of regular plastic.

Getting spare parts from the original manufacturer is often not as easy as you might think. Even in the case of the tractor used by the igus® cleaning team for various tasks, such as gritting the site, the manufacturer was unable to provide a new gear. The broken gear serves as a starter for the engine's large ring gear. The load applied to the gear each time the engine was started was too high for the component made of regular plastic and wear and breakage quickly set in. A special gear was therefore needed that would fit precisely, be wear-resistant and have good sliding properties.

The 3D printing team tackled the problem and was able to produce a drawing of the original based on the broken gear. This was converted into a STEP file and then printed using selective laser sintering with iglidur® i3. At €28 per piece, the costs of tool-free 3D printing were a good 10 times cheaper than mechanical production, which would have cost more than €300. The special shape of the gear with the spindle geometry inside is no problem for additive manufacturing. In addition, the printed gear promises a longer service life than the previously used gear thanks to the high abrasion resistance of the material. This meant that the tractor could be saved from being scrapped and returned to full working order.

One of the biggest advantages of 3D printing is the almost limitless freedom in the design of the desired components. There is hardly a mould that cannot be produced in a single pass. So when it comes to producing a spare part that can either no longer be supplied by the manufacturer or is of a special type, the 3D printer is the right choice. Spare parts are often only required in small quantities. In this case too, it is significantly cheaper to have the components manufactured using the additive process. The tool-free and resource-saving production results in cost-effective quantities. In the case of the tractor, only one gear was required. This would have cost more than €300 in mechanical production - in 3D printing, the piece cost €28.

At igus®, there are various ways to have a gear printed. Design engineers, for example, can use the igus® gear configurator to configure the required gear and then order it directly from igus®. How exactly this works is explained here. Alternatively, an existing CAD model can be uploaded to the 3D printing service and ordered with the appropriate igus® material and manufacturing process.

Various load tests are carried out in the igus® test laboratory. All igus® products are put through their paces in order to make the online tools reliable and meaningful. One of these tools is the service life calculator for gears, with which the service life of gears made of iglidur® i3 or iglidur® i8 can be calculated depending on the application-specific load data. This makes it easy to check whether the material is suitable for your application and when you should change the gear before it fails.