Ergometers with Injection Molded Bearings for Cardiovascular Care

Maintenance-free special plain bearings from igus as a fast and economical solution for recumbent bikes by ergoline GmbH

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 of ergometers is ergoline GmbH. The company’s tilting-recumbent ergometer relies on highly wear-resistant and self-lubricating iglide plastic plain bearings. So that the company could start production quickly on its newest series, ergoline engineers used the cost-effective FastLine injection molding service from igus®. Within four days, igus developed the appropriate tool, injection-molded the parts, and delivered the first plain bearings to ergoline.

According to the World Health Organization, cardiovascular disease (CVD) is the leading cause of death globally, taking an estimated 17.9 million lives each year, representing 32 percent of all global deaths. Additionally, one-third of these deaths occur prematurely in people under 70 years of age. Consequently, detecting CVDs in the earliest stages could mean the difference between life and death for thousands of people worldwide.

An exercise electrocardiogram (ECG or EKG) test is an essential diagnostic tool in assessing and monitoring heart health. The ergometer measures the heart’s electrical activity, blood pressure, and heart rate in response to exercise stress.

Based in Bitz, near Albstadt, Germany, ergoline GmbH is a leading manufacturer of medical ergometers. For more than 30 years, ergoline has specialized in developing a wide range of equipment used for cardiac diagnostics. The company also develops equipment and software for training and monitoring patients in cardiac rehabilitation. The company has already put more than 60,000 ergometers into use worldwide.

These systems are quite common in rehabilitation clinics and sports medicine centers,” says Dominik Huber, Head of Design at ergoline GmbH. “All components, even the bearings, must be durable and able to withstand a wide range of loads, such as acceleration and high weight.

Tilting function supports heart ultrasound

The ergoselect 1200 is a specialized reclining ergometer developed by ergoline. This newest device was designed for a particular heart examination called a dynamic stress echocardiography. The device’s inclination angle can be electrically adjusted horizontally and laterally between 0 and 45 degrees, allowing special ultrasound heart examinations during an ergometric stress test.

Quickly find the right material using the igus service life calculator

Dominik Huber was looking for a plain bearing to support the adjustment mechanism for height and tilt.

iglide P210 quickly proved to be the right material for the application,” recalls Benjamin Haupt, Technical Sales Consultant at igus GmbH. “The material works especially well with pivoting movements on various shaft materials. It is extremely wear-resistant, especially for loads of up to 20 MPa, and works well with edge loads.”

The need for external lubricants has been eliminated, so the plastic bearing meets medical technology’s stringent hygiene demands. In the ergometer application, iglide® P210 has the longest service life, as the free service life calculator that igus offers its customers also indicates. To test service life, igus operates a 3,800-square-meter test laboratory in Cologne. All test results are integrated into the igus online tools to allow statements about product service life in various applications.

FastLine: Cost-effective series parts from injection molding

Shaft modifications had given the bearings selected from the catalog too much clearance, 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 Huber.

But volume production required something even faster.

Six weeks for a regular tool was too slow for us, and continuing to turn bearings from bar stock was too time-consuming and expensive,” says Huber.

igus offered the customer its FastLine service.

By investing in our tool shop with its own production line for round parts that features modern CNC technology, we were able to produce specially shaped plain bearings for ergoline in a very short time,” says Haupt.

The time from order to delivery was just four days.

We were really surprised by the low price. We had expected to pay three times as much. Of course, we were very pleased, and it gives us the possibility to work flexibly in design,” adds Huber.

Find economical solutions together

The specially sized plain bearings are pressed into the bearing point, ensuring reliable, safe ergometer adjustment, even with up to 1.3 tons of dynamic forces. The bearings won over the users from both a business and a technical perspective.

The igus materials contain incorporated solid lubricants, eliminating the need for additional lubrication. The polymer bearings are lightweight, corrosion-free, and resistant to dust and dirt. Hence, they are ideal for use in ergometers. ergoline GmbH has been using igus motion plastics for 13 years and has already installed several thousand plastic bearings in its devices.

Huber continued, “Besides plain bearings, we rely on additional igus products in other ergometer models. For instance, we are using drylin® W linear guides for the seat adjustment mechanism in the sitting ergometer, the ergoselect 600. We appreciate the long-term cooperation with the common goal of finding a solution that is ideal from both the technical and business points of view.

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