Obvious climatic changes, increasing energy costs as well as severer and severer restrictions have recently made energy efficiency a central topic in the intra-logistics business. For years, TGW Mechanics has been developing and manufacturing its material handling and storage technology focusing on electro-mechanical optimisation. With respect to energy efficiency, this approach poses great saving potentials.
Reducing the energy consumption in the operation of automated intra-logistics systems means lower operating costs, faster amortisation and, besides, is a substantial contribution to environmental protection. For plant operators it is often a matter of finding the right measures to be taken in order to tap the full saving potential. According to the SAVE statistics of the European Union, 60 % of the energy for electrically powered systems can be saved through the optimisation of mechanical systems. This is why TGW Mechanics has paid particular attention to optimised energy efficiency in the development of their material handling products.
Weight and Power Optimised Systems
The optimum design of an intra-logistics system according to the respective requirements poses the biggest cost-saving potential. Thus TGW Mechanics has optimised its material handling systems for loads of clearly defined weight classes.
– carton and tote conveyors: up to 50 kg (110 lbs)
– tray conveyors: up to 300 kg (660 lbs)
– combi conveyors: up to 500 kg (1100 lbs)
– unit load conveyors: up to 1500 kg (3300 lbs)
Another important aspect within this still rough classification is the selection of the best appropriate drive dimensions for each project. If only one universal motor system would be used for each weight class, this system would have to be dimensioned to satisfy the maximum requirements and would thus be oversized in most cases. Thus TGW Mechanics configures each drive individually subject to factors such as conveying speed, payload and function. The drives used for pallet chain conveyors, for example, have a power range between 0.55 and 3.0 kW.
Focus on Construction Details
An important factor in mechanical design engineering of all material handling devices is the selection of the right drives and gears, as the efficiency levels of these components considerably influence the system’s overall efficiency. TGW exclusively uses spur and bevel gears as well as drive systems that optimally meet the functional requirements, thus achieving efficiency levels of 94 to 98 %. Worm gears and v-belts are generally not in use due to their obviously lower efficiency levels.
The use of high-quality components has a considerable effect on energy efficiency, too. All bearings, rollers and sliding elements have to allow high efficiency levels in order to be applied in TGW devices.
Lightweight Construction with Dynamic Axes
Particular attention has to be paid to the reduction of moving mass. Therefore, TGW consistently uses lightweight construction materials, especially with transfer cars, vertical conveyors and sortation systems. By reducing the moving mass the dimensions of the drives can also be reduced, thus being able to cut down on energy consumption, too.
The use of counterweights in lifting devices may thus seem quite contradictory. But using counterweights, for example with pallet lifts, reduces the mass difference to the lifted weight and consequently the drive power required for lifting, which again reduces energy consumption.
According to the SAVE statistics, the potential energy savings with energy-efficient motors amounts to 40 %, 3/4 of which is due to electronic speed control. Especially with dynamic applications that require frequent accelerations, variable-frequency drives contribute to an increase in energy efficiency. Therefore, TGW has been relying on electronic speed control for years. About 70 % of all drives used in transfer devices of the unit load conveyor product family are already variable-frequency drives. TGW Mechanics always equips lifts, transfer cars or sorters, which often require higher drive capacities than normal material handling and transfer devices, with variable-frequency drives.
The SAVE statistics imply that only 10 % of potential savings can be generated by the use of energy-saving motors which will have to be employed, according to EU directive, in a power range higher than 0.75 kW as from 2011. But with carton and tote conveyors which have a maximum payload of 50 kg (110 lbs) TGW uses drives under 0.75 kW in 80 % of applications. There are no energy-saving motors (of efficiency class IE2 and IE3) available in this power range, which again increases the importance of electronic speed control. TGW already uses IE2 drives as an option in power ranges higher than 0.75 kW, but in most cases TGW makes use of the even more efficient variable-frequency drives.
Own Calculation Tool for Energy Consumption
Apart from the above-mentioned electro-mechanical details, operators of automated intra-logistics systems are also interested in the total energy consumption and the corresponding costs to be expected. TGW Mechanics developed a tool which permits operators to calculate the estimated energy consumption already during the planning process. On the basis of several key parameters this calculation tool allows for quite reliable statements on the connected value of the installation, energy consumption per hour, day or year as well as projected annual energy costs. The results of the calculation tool have already been validated with real measured data of installations that are already in use, giving proof of the tool’s reliability.
Energy efficiency will certainly continue to be a central topic of automatic intra-logistics solutions in the next few years. TGW will make every effort to find the most efficient solution to the customers’ specific performance requirements, combining the best appropriate mechanical technology with intelligent control components.
TGW Mechanics GmbH