Ergometers are not only popular in gyms or as exercise machines at home - they are also used in medical technology for diagnosing heart diseases. One of the leading manufacturers is ergoline GmbH. For its tilt-recline ergometer, the company relies on highly wear-resistant and lubrication-free iglidur polymer bearings in special dimensions. So that the company could quickly start production of its new series, it used the cost-effective FastLine injection moulding service from igus. Within four days, the appropriate tool had already been manufactured, injection moulding had started and the first plain bearings were at the customer's premises.
A plain bearing for loads up to 20 MPa was sought for the volume production of this tilting recumbent ergometer. The main problem: the required dimension was not available from stock. The plain bearings should also do without the use of additional lubricants so that the use in the ergometer is hygienic.
With the FastLine service from igus, an injection moulding tool for series production of the desired plain bearings was manufactured within a very short time. Within 4 days, Ergoline GmbH received the first custom-made plain bearing made of the material iglidur P210, which fulfils the desired requirements for loads and lubrication-free use.
According to the RKI, cardiovascular diseases are the leading cause in Germany for about 40 per cent of all deaths. People over the age of 60 are particularly affected. One of the most important examinations for the diagnosis of these diseases and for the control of an initiated therapy is the performance of a stress ECG. Medical ergometers are used for this purpose to ensure reproducible stress for the patients. Ergoline GmbH from Bitz near Albstadt is the leading manufacturer of these ergometers. For more than 30 years, the company has specialised in the production of high-quality medical ergometers in a wide variety of designs. Ergoline has already put more than 60,000 ergometers into use worldwide, and with great success. On the one hand, the company manufactures devices that are used for cardiac diagnostics (for example, to perform stress ECGs in clinics and doctors' practices); on the other hand, the specialist develops devices and software for training and monitoring patients in cardiac rehabilitation, for example, after a heart attack or bypass surgery. "These systems are found, in particular, in rehabilitation clinics and sports medicine centres", says Dominik Huber, Head of Design at Ergoline GmbH. All components - such as the installed plain bearings - must be durable and withstand a wide range of loads such as acceleration and heavy weight.
Dominik Huber was looking for a suitable plain bearing especially for the bearings of the height and tilt adjustment. "With iglidur P210, we were able to quickly identify the right material for the application", recalls Benjamin Haupt, Technical Sales Consultant at igus GmbH. The material is particularly suitable for pivoting movements on various shaft materials. Especially for loads up to 20 MPa, it is extremely wear-resistant, and it is also well suited for edge loads. By dispensing with external lubricants, the polymer bearing meets the high demands for hygiene in medical technology. In the ergometer application, iglidur P210 has the maximum service life, which is also shown by the service life calculation that igus offers its customers with the help of a free calculator. For this reason, igus has a 3,800 square metre test laboratory in Cologne. All test results are integrated into the igus online tools to make statements about the service life of the products in the various applications.
The bearings selected from the catalogue had too much bearing clearance due to modifications to the shaft, so another solution was required. "Since production was about to begin, we initially decided to turn a small number of the parts from bar stock", explains Dominik Huber. For volume production, however, it had to be even faster. "Six weeks for a regular tool was too slow for us, and permanently turning bearings from bar stock was too time-consuming and too expensive", the designer notes. igus offered the customer its FastLine service. "By investing in our tool shop with its own production line for round parts with modern CNC technology, we were able to produce plain bearings in a special shape for Ergoline within a very short time", explains Benjamin Haupt. It took just four days from order to delivery. "We were particularly surprised by the cost-effective price. We would have expected a sum three times higher. Of course, we were very pleased about this and it gives us the opportunity to work flexibly in the design", adds Huber.
The plain bearings in special sizes are pressed into the bearing location, and enable a reliable and secure adjustment of the ergometer, even with dynamic forces of up to 1.3 tonnes. The bearings convinced the users from both an economical and a technical perspective. The igus materials contain incorporated solid lubricants, making additional lubrication redundant. The polymer bearings are light, corrosion-free and resistant to dust and dirt. Therefore, they are ideal for the use in ergometers. ergoline GmbH has been placing its trust in igus motion plastics for 13 years, and has already installed several thousands of plain bearings in its devices. "Apart from plain bearings, we use further igus products in other ergometer models. For instance, we are using drylin W linear guides for the seat adjustment in the sitting ergometer, ergoselect 600. We appreciate the long-term co-operation with the goal: find a solution that is ideal, both technically and from an economical point of view."