A remarkable 25 Memmert heating ovens and Peltier-cooled incubators are in use at Bayerische Kabelwerke (BayKa) in Roth. Despite the demanding production environment, there are hardly any failures, as Benedikt Spangenberg, Head of Development, confirms. The oldest device has been drying materials for cable production around the clock in the signal cable factory since 1988. This long-standing reliability of their products is one of the qualities that our two companies share. During an exciting on-site visit, we witnessed firsthand how Memmert appliances are used in development, quality assurance, and during cable production.
At the end of the 19th century, Bayerische Kabelwerke (Bayka) was one of the first companies in Germany to manufacture insulated electrical cables. Later, they supplied modern fiber optic cables for the infrastructure expansion of Deutsche Post and Deutsche Bahn. Today, the traditional site develops cables and wires for digital production, modern buildings, the transportation revolution, and energy transmission. Bayka’s portfolio includes around 1,200 cable types, and with the amount produced annually, one could easily circle the globe.
Many of the cables and wires must function reliably for decades. The durability of cable materials against chemical, physical, and mechanical influences is therefore extremely important and is proven in standardized material tests. For many of these tests, cable samples are stored in Memmert heating ovens for up to 168 hours at temperatures ranging from 70 to 250°C.
“We at Bayerische Kabelwerke promise our customers the highest quality and precision,” says Benedikt Spangenberg, Head of Development at BayKa. “That’s why we rely on partners for our material tests and applications who share the same high-quality standards. We found such a partner in Memmert. We and our customers can count on reliable test results and top-notch quality. Particularly, the very good spatial temperature distribution of Memmert devices has convinced us.”
Our tour first stops at the test laboratory, where four Peltier-cooled incubators (IPP) are currently testing the microbial resistance of cable sheaths. Next, we examine an aging test in the heating oven. This test simulates changes and the durability of material properties under accelerated conditions. In simplified terms, the lifespan of cables and wires halves for every 10°C increase in temperature, as oxidative and corrosive aging processes occur more quickly at higher temperatures. Thermal overload also attacks insulation.
When Bayka cables need to be particularly heat-resistant, flame-retardant, or designed for high transmission voltages, crosslinked special elastomers or crosslinked polyolefins are used. During the extrusion of plastics onto the conductor, chain molecules are crosslinked in a special process.
This improves the heat resistance, thermal pressure resistance, stress crack resistance, chemical and abrasion resistance, as well as the flexibility of the conductor insulation. Crosslinked materials no longer melt in the event of a short circuit and are thermomechanically more stable than the base polymers. As the quality of the crosslinking contributes significantly to the functionality and longevity of cables, the degree of crosslinking of each batch is controlled with a thermal elongation test, also called the Hot-Set Test, both during production and as a final inspection.
For this test, sheath or insulation samples are attached to a stand, weighted, and then heated to 200°C in Memmert natural convection ovens. The measured elongation and residual elongation provide insights into the degree of crosslinking.
The thermal elongation test is described in DIN EN 60811, the most important European standard series for material testing in the cable industry. Memmert ovens are also used at BayKa for tests on thermal pressure resistance, stress crack resistance, thermal shock behavior, shrinkage, oil resistance, and life testing.
For energy, signal, and telecommunications cables installed in the ground or ducts, a longitudinally water-tight cable structure with special water-swellable material is often required. This prevents water from penetrating the cable longitudinally if the outer sheath is damaged, for example, during construction work. In the event of damage, the swellable materials applied to the conductor insulation immediately react with water, sealing the cable at the damaged point. To ensure that the pre-stored swellable tapes and yarns are completely dry, they are dried in large Memmert drying ovens at 60°C for 24 hours before processing on the production line.
The collaboration between Bayerische Kabelwerke and Memmert, both from the Nuremberg Metropolitan Region, represents a true win-win situation. This partnership is characterized by a shared pursuit of the highest quality and a strong focus on customer needs.
The impressive factory tour, organized by Mr. Spangenberg, Head of Development at BayKa, and Mr. Sorge, Head of Marketing at BayKa, provided deeper insights into the production processes and quality standards of Bayerische Kabelwerke.
Memmert would like to sincerely thank Bayerische Kabelwerke for their kind support in creating this article and the opportunity to visit the production facilities. This partnership demonstrates how innovative solutions can be developed through close collaboration and mutual support, meeting the high demands of both companies.
We look forward to continued successful cooperation and are confident that this partnership will lead to outstanding results in the future.
