Put to the Ultimate Test – Part 6: Aging Tests
During the development of our cables and wires, each product undergoes rigorous testing in our in-house laboratories. In part six of our series, we take a closer look at how we conduct aging tests.
Cables and wires used in industrial and infrastructure applications typically have a service life of around 20 years. During that time, they must withstand mechanical stress without developing age-related damage such as cracks or breaks. To ensure this durability, organizations like VDE and UL have established standards that define the types of aging resistance these products must meet. One key factor is thermal aging—how long a cable can maintain its functionality at a given ambient temperature.
At HELUKABEL, we conduct rigorous aging tests in accordance with these standards. Since waiting 20 years for results isn’t practical, we simulate the aging process using a specialized aging oven. This equipment recreates specific environmental conditions to accelerate material aging. Test duration and temperature are defined by the applicable standard, with typical test periods lasting seven, ten, or fourteen days at temperatures between 100°C and 155°C. Before and after testing, we measure the tensile strength and elongation at break of the plastic materials. Only if these properties remain unchanged can the material pass the aging test.
Because our cables are used in a wide range of environments and applications, we also test their resistance to various substances in our laboratory. In addition to using a specialized hydraulic test oil known as IRM 902, our experts frequently evaluate materials in customer-specific media as well. Sheath and jacket compounds are submerged in these substances for several days. Only if the materials retain their required mechanical strength after this simulated aging can they be approved for use in cable production.
Ask the Expert
Which insulation and sheath materials are especially resistant to aging?
That depends heavily on the specific application. Generally speaking, crosslinked materials—like those used in our high-temperature HELUTHERM cables—offer the highest resistance to aging. Polyurethanes also perform well, while PVC tends to degrade more quickly over time. In practice, many additional factors come into play, such as whether the materials are halogen-free or flame-retardant, and whether the cable is used in a fixed or flexible installation. Aging resistance can also be influenced by material blends or the use of specific additives.
What can be done to make a cable more resistant to aging?
Of course, the plastic compound used plays a major role in aging resistance, but manufacturing processes are just as critical. This is especially true during extrusion—when the molten sheath or insulation material is forced through a die to coat the conductor beneath. Every process parameter must be carefully selected to ensure the finished cable meets the required durability standards. If a material fails the aging test, we first look for opportunities to improve the manufacturing process. If that doesn’t produce the desired results, we switch to an alternative compound better suited to the specific application.
