Motor cables in small bend radii
Alexa Heinzelmann | 30. November 2022
Anyone looking for a parking space in big cities these days quickly realises that space is often a problem. Cars are getting bigger and, moreover, there are now significantly more vehicles on the roads than was the case 20 or 30 years ago. However, if you compare the interiors of modern cars with those from the 1980s, you will quickly discover that modern cars, for example, have a significantly smaller boot. Firstly, this is due to the fact that modern cars have a significantly safer passenger compartment. The spars are much stronger and therefore thicker. In addition, cars now also use more technology, which must also be integrated in the vehicle. What’s more, the interiors are more clad to make it look more beautiful.
The situation is similar for machines and systems. Modern machines have significantly more technology today. In addition, the market requires machines to be more compact, which also has an impact on the installation space for energy chains. As a result, an increasing number of cables for sensors and bus transmission must also be placed in the energy chain together with motor cables, with the smallest possible bend radii.
Problems with motor cables in small radii
Especially for machines that require powerful motors, such as when producing display glass for large televisions, a bend radius of 175mm can be a challenge. A shielded 4G16mm² motor cable often has an outer diameter of between 22mm and 25mm. If you calculate the bending factor, it is found that with an outer diameter of 23mm, a bending factor of 7.6xd is produced with the above-mentioned chain radius. Of course, there are cables that are designed for such bend radii. However, it should be noted that straight cables with large cross sections are very stiff due to the high copper content. As a result, the plastic materials are heavily stressed when used in the energy chain, which can lead to jacket breaks. With long travels, soft jacket materials, such as PVC, can also cause corkscrewing.
Make sure you have the right outer jacket
igus offers chainflex motor cables with outer jacket materials made of PVC, PUR and TPE. Applications with small bend radii represent high mechanical stress. For this reason, we also recommend cables with a halogen-free TPE outer jacket, as this is the most durable and has a significantly longer service life expectancy compared to PVC and PUR. In addition, TPE cables offer high oil resistance and are resistant to a wide range of chemicals. The abrasion behaviour of TPE is also significantly better than that of PVC or PUR cables. All halogen-free TPE cables from igus have UL approval and can therefore also be used in the USA. In our 3,800m² test laboratory, we tested a shielded 4G25mm² motor cable with a bend radius of 175mm to find out how long this cable would last with sagging. You can see the results here.
Another solution is to switch to four single cores instead of a four-core cable. The advantage is that even a smaller chain bend radius can be selected. In addition, this solution often offers price savings. In the crane industry, STS cranes have been implementing this for many years.
Calculate the service life
Do you have a demanding application and would like to know how long a chainflex cable lasts? With our service life calculator you can easily calculate the service life of your application. Furthermore, igus offers a guaranteed service life of 36 months and up to 12.5 million double strokes for all chainflex cables.
Feel free to contact us to help you choose the right cable.