Green approach to energy chains
25 January 2013
Some of the latest green cable management systems can provide up to 57% energy consumption savings compared with traditional systems, says Justin Leonard, director at igus UK. Here, he reviews the latest polymer energy cha
With demand for manufacturers to increase energy efficiencies and reduce costs of their operations, plant managers and engineers are reviewing all aspects of their facilities to identify where energy savings can be made. A key aspect of machines are the energy chains used to carry cables for power transmission, electricity and fluids, as well as sensitive bus, data and fibre optic cables.
Reducing drive power Energy chains are an important part of many machines, being the principle method of carrying, guiding and protecting moving cables and hoses. Lubricant-free plastic energy chains can be used unsupported for shorter travels or gliding for longer travels.
Despite being made from lightweight but robust technical plastics, they still have a direct influence on how much energy is used in the plant. How much push-pull force, in other words drive power, is required at a given speed to move an energy chain affects how energy efficient it is. The more power that is required, the more energy is required, and therefore it will cost more to operate.
Thus, by reducing drive power, energy usage and costs can be reduced. Friction, size and weight of the overall system all determine how much drive power is required and how much energy is used.
For shorter unsupported travels, lighter cable management systems mean less energy required. This in turn means that smaller motors, drive control and frequency converters can be used. Newer energy chains, such as the igus E4.1 system have various design features which add strength without adding weight, so in many cases a smaller, lighter size of energy chain can now be used for the same application requirements. This means up to 17% drive power can be saved.
Traditionally gliding energy chains, i.e.
where the upper run slides on the lower run, are used on longer machine axes. These modular systems have been used effectively for many years, however, as the top run moves over the bottom run, extra friction is incurred.
In recent years, energy chains have been developed that incorporate rollers, which significantly reduce friction and therefore energy loss. Tests at igus have proven that for the same application conditions (fill weight, chain length, speed and acceleration) it has been possible to reduce the friction factor from 0.3 to less than 0.1. On travel distances of 40 to 50m and more, that reduces the electricity and operating costs significantly.
In this way, the igus rol e-chain provides a reliable solution for long travel lengths of up to 800m, speeds to 6m/s and for cable loads up to 50kg/m. The steady rolling resistance in machine applications, even in dusty and dirty conditions, means users can realise energy savings of up to 37%.
The energy chain system P4 from igus, for example, takes this further. It also features rolling technology and has been developed for plant and machinery manufacturers on applications such as loading gantries for automated production processes, where speeds are getting even higher, (up to 10 m/s) and travel lengths longer (to 800m and more). In this way the energy consumption saving can be even greater.
Cable selection Having chosen an energy efficient cable carrier, other aspects to consider are the quality of the cables themselves as cables especially designed for energy chains can also help directly in reducing energy consumption. Optimised sheathing mixtures, matched to the energy chain application, can achieve low abrasion resistance. High-quality sheathing materials can be extruded with an extremely thin wall, which saves up to 18% in weight compared with conventional cables.
Cable insulation materials should also be considered. With high-quality materials, significantly higher currents can be carried through the same electric cross-sections, or vice versa, the cross-sections can often be reduced without the electrical performance being diminished. This allows weight reductions of up to 30%.
The use of the correct cable sheathing and insulating materials can ultimately save drive power requirements by up to 17%.
By understanding all aspects for reducing the driving power, energy efficiency of a plant can be increased significantly. Through installing high quality energy chains and flexible cables from a supplier that can provide sound advice and guidance, engineers can make energy consumption savings of up to 57% in total.