EoW January 2009

technical article

3 Productivity The capacity of a colouring line is a function of many variables including line speed, the supply and take-up spool capacities, and the acrylate capacity. The combination of fibre supply and ink capacity determines the maximum run length between set-ups. The maximum fibre length is limited by the capability of the OTDR to accurately measure fibre loss to assure that shorter lengths used in completed cables will meet final test requirements. The capability to measure long lengths of single mode fibre at 1,550nm is over 100km, and at 1,310nm is in the 70 to 80km range. Inks are typically supplied in 1 or 2kg bottles. Even a 1kg bottle has more than enough capacity to colour 100km of fibre. Other factors affecting productivity include start-up scrap, set-up times, maintenance time and operator interference time, which is a function of line manning. The impact of these factors upon pro- ductivity was studied using a model. An example is shown in Figure 7 where it is assumed that the supply length equals the take-up length. It can also be assumed that multiple cuts could be made from a given ink and fibre supply. Note that as the line speed increases, the sensitivity to supply spool length significantly affects line output. This provides the incentive for longer process lengths to take full advantage of the speed capability. For example, a change from 1,500m/min with 25km lengths to 3,000m/ min with 50km lengths would increase the daily line output from 1,175 fibre km to 2,305km, a 96% increase. The assumptions include a 55 minute work hour to account for operator interference, 15 minutes maintenance per shift for centre tube changes plus any electrical or mechanical work, 10 minutes per setup, which includes ink and spool changes plus string up, a 60 second ramp to 3000m/min and 10 minute start-up scrap. To minimise set-up times, clean die assemblies and new ink containers can be swapped to allow for offline cleaning and ink changes. Vacuum is also provided to the die to minimise ink drip during shutdown or a fibre break. Both on and off line automatic die flush systems are also available. The typical pressurised ink container holds a 2kg bottle, but 1kg containers are available. Even larger containers of 10kg and 20kg bottles are available for fibre upcoat products. Two options are available for pay-off and take-ups, the standard 7kg spool (ie 50km of fibre) and a larger 25kg supply for upcoated products.

Figure 7 ▲ ▲ : Line output/day

4 Conclusions The result of the key line component improvements is a new high speed colouring/upcoat line with the potential for speeds up to 3,000m/min. The line includes a new coating applicator and more efficient UV curing system with inert atmosphere controls. Also included is a greater range of pay-off and take-up sizes and a robust responsive drive system. These essential components of the process were proven to perform via extensive testing and curing level measurements. Previous developments of UV upcoating and ring marking were incorporated into the new design to provide the flexibility to manufacture a wide variety of products. n 5 Acknowledgements The authors wish to thank many co- workers at Nextrom and Keqi Gan and others at DSM Desotech for their assistance with the colouring trials plus the RAU and the MEK rub measurements.

[2] Eva Montgomery, Ed Murphy, Keqi Gan, Ken Drake, Nathan Drake, ‘UV-Curable Buffer Resins vs Thermoplastics: A Closer Look at New Flame Retardant, UV-Curable Materials in Tight Buffered Cables’, Proceedings of the 52 nd IWCS/Focus, 98-101 (2003). [3] Rick Chamberlain, Paul Schmugge, Bob Stulpin, Harri Turunen, Tim Dougherty, ‘Optimisation of UV-Curing Multiple Elements by On-Line Measurements’, Proceedings of the 54 th IWCS/ Focus, 83-88 (2005). [4] Harri Turunen, Tim Dougherty, Jari Nykänen, Eva Montgomery, Keqi Gan, ‘The Manufacture of UV-Curable Buffered Optical Fibers’, China International Wire and Cable Conference (Non-Ferrous) Wire China 22 nd -23 rd September, 94-103 (2004).

Nextrom USA Inc 1230 Commerce ST SW Conover, NC 28613 USA Fax : +1 828 328 4956

Email : info.usa@nextrom.com Website : www.knillusa.com Nextrom OY Vantaa Finland Fax : +358 9 5025 3003 Email : info@nextrom.com Website : www.nextrom.com

6 References

[1] Tim Dougherty, Harri Turunen, Jari Nykänen, ‘Buffered Optical Fibre Manufacturing Developments’, Proceedings of the 52 nd IWCS/ Focus, 616-622 (2003).

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EuroWire – January 2009