Energy chain systems not only transport power, data and control signals to machines, they also have a part to play in their overall energy efficiency. How much force is required at a given speed to move an energy chain? How light or stable can energy chains be made in order to carry out their purpose reliably with minimum energy consumption? Modern plastic energy chains are finding favour among machine builders because of their potential for minimising mechanical losses and hence improving the overall energy efficiency of the machine or system on which they are installed.
According to energy chain specialist, igus, energy consumption can be substantially reduced by using appropriately designed, lightweight energy chains. If a roller energy chain is used in place of a sliding version in an application involving long travel distances and high fill weights, friction losses are reduced at a stroke. Indeed, tests carried out by igus show that with the same basic data (filling, chain length, speed and acceleration) the friction factor can be reduced from 0.3 to less than 0.1. For one sliding energy chain user, a drive power reduction of 37 percent was achieved simply by adopting an equivalent capacity roller chain.
There are many applications of roller energy chains being deployed over long distances. A good example is the 550m chain used in a taconite mine in Minnesota (USA); another is the longest plastic energy chain in the world so far - a 615m installation at the Czech lignite-fired Tusimice power plant. The trend now is for lighter, lubricant-free plastic roller energy chains to be adopted in place of metal chains, even for the toughest of working environments.
As well as reduced friction, reductions in size and weight can also have a positive impact on energy losses associated with roller energy chains. Comparative tests carried out by igus at its technical centre indicate that 17% drive power can be saved with smaller energy chains that offer equivalent robustness, thanks to careful design. In these tests, an energy chain from igus' E4 range was chosen. E4 is a modular system that can be adapted for a variety of applications, including side-mounted and hanging configurations, for travel distances in excess of 200m. The latest addition to this range - the E4.1 - combines design details from previous energy chains with innovative new features.
Another factor affecting the energy efficiency of cable carrying chains is the cable itself. Chainflex cables, which igus has specifically developed for energy chain applications, make use of high-grade sheathing and insulating materials. Depending on the combination of cross-sections and cables used, igus tests indicate that combinations of its lightweight energy chains and Chainflex cable can save between 5 and 30% in terms of energy consumption, meaning that the drive power can be reduced by around 17%.
Optimised sheathing materials, matched to the energy chain application, can achieve low abrasion resistance, while high-quality sheathing materials can be extruded with an extremely thin wall, which saves up to 18% in weight compared with conventional cables. With high-quality insulating materials, significantly higher current carrying capacity can be achieved with the same core cross-section. Moreover, cross-sections can often be reduced without compromising electrical performance, again allowing weight reductions of up to 30%.