Long-stroke ball screws drive optimisation of 5G fibre optic filament production
02 November 2020
Fundamental ball screw technology hasn’t changed much since 1929, when Rudolph G. Boehm patented what he called an “anti-friction” nut. The ability to move heavy loads smoothly and precisely is a key process which continues to enable engineering innovation today.
Nowhere is this more evident than in the production of fibre optic filaments, where ball screws are helping manufacturers meet the growing demand for fibre optic cable generated by 5G communications.
Delivering fibre optic strands for 5G communications
Wireless carriers are just beginning to roll out 5G communications, but even the most conservative estimates are projecting at least a 10-fold speed increase over 4G. This will impact everything from cell phones and laptops to driverless cars. The realisation of 5G communications is boosting the demand for high-bandwidth fibre optic cable, which requires continuous improvement in the fibre optic manufacturing process. This begins with the creation of preforms – highly treated, multi-layered silicon rods. These provide the silicon that will eventually be drawn into filaments that are approximately the width of a human hair. They are joined with hundreds of similar strands to produce the fibre optic transmission cables that will carry the 5G signals.
To start the conversion of the preform into a single strand, a technician climbs to the top of a drawing tower and loads it into a feed mechanism that will lower it into a high-temperature furnace. Once the preform arrives at the heating element, gravity takes over, and the molten silicon drips and narrows to its intended diameter. As it cools and hardens, the filament passes through a laser micrometre to assure 99 percent width consistency. It is then pulled onto a take-up spool that will gather as much as 10 kilometres (6.2 miles) of filament before being transferred to a fabricator for incorporation into the final cable.
Critical to the success of the process is the control over the speed with which the system feeds the preform. Due to the thin nature of the fibre, slow and steady movement of the feed unit (one metre per hour) ensures that the production is stable. Any faster than that, and the furnace will be unable to melt the preform fast enough. Anything slower will break the continuity of the stream. Many of the world’s leading fibre optic wire producers accomplish this with ball screw technology, which provides high stability and smooth movement at such low speeds.
Read the full article in the November issue of DPA
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