Planning reliability through vertical integration
Predictability is important for the fiber optic cable industry. Kurre Spezialmaschinenbau therefore relies on almost 100 percent vertical integration. The machines "are designed on the basis of a detailed customer specification in a modern 3D design environment, then manufactured in-house, assembled and shipped to customers all over the world after extensive commissioning." The vertical range of manufacture means that "spare and wear parts can be reproduced for life and are available at all times", emphasizes Thorsten Wilde.

In addition to machines for the pure manufacturing process in the drawing tower, glass fiber production primarily requires extruders, unwinders, winders, accumulators, haul-offs, cooling troughs and various measuring systems.

The extrusion process plays a decisive role in the quality of the fiber optic cable. Around a dozen light-conducting glass fibres are combined in loose tubes "and loosely encased in a highly rigid and stabilizing polybutylene terephthalate (PBT) tube in an extrusion process," explains Dr. Simon Kniesel from Product Development Engineering Plastics at BASF. The sheathing takes place during a continuous automated extrusion process. "The individual fibers are drawn from various drums into the tube, which is produced online during the extrusion process, at speeds of up to 500 meters per minute."

Thinner cables, higher bandwidth
But which material should be used for the sheathing? It is essential that the melt solidifies quickly during the extrusion process and that the finished loose tubes have a high degree of rigidity. Another challenge from Simon Kniesel's point of view is that, on the one hand, the global demand for fiber optic cables is growing, while on the other, the space available in overhead lines and cable ducts, as well as in building-internal cabling and optoelectronic assemblies, is limited. "The cables must therefore become thinner and thinner while the information density remains constant." To meet these stricter requirements, BASF has developed a new Ultradur grade specifically for thin glass fiber sheathing. Other companies are likely to follow this example with their own developments.

The development of stranding is also being driven forward by the industry. Rosendahl Nextrom, for example, has improved its SZ stranding for fiber optic cables. According to the company, speed is a key factor in the performance of the machines. With a line speed of up to 200 m/min, the loose tubes are stranded at 2500 ^min-1.

Protecting the fibers in the cable
When manufacturing fiber optic cables, it is important to protect the fibers in the cable. They must also be able to withstand stresses such as moisture and tensile force over the long term. "Typically, fiber optic cables are given an insulation layer made of polyethylene as an outer protective sheath," explains Sikora. Usually, a measurement of the wall thickness of the insulation layer is required for this type of cable. Measuring the diameter is also important, but a diameter measurement alone is generally not sufficient.

Sikora has developed devices that determine the diameter, minimum wall thickness, eccentricity and quality using X-ray images. The measured values are recorded within fractions of a second using an X-ray-sensitive image sensor. "The measurement technology is particularly interesting for fiber optic cables in terms of the savings potential," continues Sikora.

Digitalization will continue to result in high demand from the metallic and fibre optic cable industry. "At the same time, the requirements for the transmission speeds of the cables used and the technology as a whole will also increase due to rising end consumer demands," predicts Thorsten Wilde. As these properties are directly related to the quality of the production equipment, expectations of drive control systems will increase.

Fiber optic expansion increases in intensity
The forecasts for manufacturers and suppliers in the fiber optic cable sector are promising. "High-performance connections with symmetrical bandwidths and a dedicated quality of service are already in demand in various sectors, for example in the financial and insurance sector, in the automotive industry, in the medical sector and everywhere else where large amounts of data need to be transported quickly and securely from A to B," summarizes Wolfgang Heer, Managing Director of Bundesverband Glasfaseranschluss e.V. (Buglas).

The association assumes that significant investments in additional fiber optic-based networks must and will be made in all countries, particularly in the areas of machine-to-machine communication and the Internet of Things and in the area of energy supply - where energy is increasingly being fed into the grids on a decentralized basis as a result of the energy transition, triggering a growing need for control and regulation in the distribution grids.

Germany's importance as a market for fiber optics will increase. "We assume that the expansion of fibre optics will increase considerably in the coming years," emphasizes Heer. On the one hand, because the "hunger for bandwidth" will continue to grow, enabling further expansion projects to be carried out by private companies, and on the other, because the federal broadband funding program, which has been topped up with state funding, will see around three to six billion euros flow into the expansion of previously underserved areas, the so-called white spots, by the end of 2018 alone.

"Our country is the strongest economy in Europe not because of, but despite its broadband coverage. To keep it that way, Germany in particular will (have to) continue to invest heavily," says BUGLAS Managing Director Heer. The production and laying of optical fibers is therefore about nothing less than the health of an economy. Which should be motivation enough for everyone involved. am