Energy Efficiency In Intralogistics: Lowering Costs, Protecting The Environment.

In the scope of the Blue Competence sustainability initiative of VDMA, an intralogistics technology supplier takes on board responsibility for economy, ecology and society. The objective is minimization of the energy and resource consumption by innovative Technology.

Opportunities for optimization of energy consumption
Energy consumption not only depends on the automatic conveyor and warehouse technology. The greater part of the energy consumption relates to heating/ventilation, lighting and other consumers. Therefore, it is necessary to choose a holistic approach when energy consumption should be reduced. Beside to the conveyor and warehouse technology the building technology is important. The processes and procedures of the operation of an automated system also have great influence.

Lowering costs, protecting the environment

The Blue Competence initiative of the VDMA helps to find sustainable products and companies who adopt sustainability. GEBHARDT decided early on to place its products and services under the Blue Competence flag of the VDMA. It has always been our objective to develop machines that keep the energy consumption as low as possible. This objective becomes more and more important particularly in times of increasing energy prices. GEBHARDT combines innovative software with advanced mechanics to achieve this objective. Optimization that only includes individual components utilizes only a small part of the optimization potential. In intralogistics the overall system must be monitored. The reduction of energy consumption often goes hand in hand with the also welcome effect of wear reduction. Both together reduce the operating costs and make the logistics center more efficient.

Suppliers of automated intralogistics systems have many opportunities to influence the energy consumption of the logistics center:

Light-weight construction

Especially in the area of warehouse technology it is important to implement targeted lightweight, because the reduction of the moving mass is the first step to reduce energy consumption. Extensive simulation tools, such as FEM, are necessary in the product development. This leads to the use of innovative materials and bonding techniques, such as gluing. The composite-miniload Cheetah is the pioneer in this industry here.

Dynamic adjustment / run on demand

The energy usage in logistics centers and thus also in automatic small-parts storage can fluctuate considerably during the course of the day. There is a great savings potential here. Smart dynamics adjustment allows for energy saving particularly in the traveling axis. Smart algorithms analyze the order loading and automatically adjust the dynamic parameters of the warehouse technology. Also conveyor technology should only run if there is something to convey. Therefore it is important to integrate an intelligent shutdown of drives. The dynamics of the conveyor system can be adapted to the order situation. Intelligent software ensures that the performance of several intralogistics components is synchronized and matched to each other. So, only the energy is consumed, which is actually needed.

Interim circuit coupling at AS/RS

The interim circuit coupling represents smart control of the traveling and lifting axis. The objective is to achieve the minimum traveling and lifting time for a maximum number of double cycles with the minimum energy consumption. The energy that is released, e.g. when the traveling axis is braked, is diverted to the lifting axis to supply the required movement of the lifting axis. This solution pays off immediately and reduces energy consumption by up to 20%.

Energy recovery at AS/RS

The energy generated in the movement and positioning energy released in the system is connected via the mains feedback device and the interim circuit of the frequency inverters. Generated energy that cannot be used in another axis can be fed back into the mains. This technology permits ASRS to save up to 50 % energy. Amortization with pallet handling ASRS is at approx. 2 years.

Software

Smart software for saving energy comprise various functions. In addition to the dynamics adjustment, the path to be travelled must be minimized, e.g. by ABC analysis. The work load management can ensure that auxiliary processes like relocations are performed in times of low work load, e.g. at night. The storage and relocation strategies must be optimized for each individual application.

Continuous improvement

Energy consumption of a logistics center can be continually improved. The improvement process must be continually revised and updated. The starting point is the evaluation of consumption data, followed by a search for potential improvements. Efficiency is increased once potential savings are identified. The results must be measured, visualized and monitored before the process is instigated.

Lightweight construction for miniload cranes: Evolution or revolution?

RBG CheetahFor many years, the lightweight construction  for storage and retrieval cranes is driven by the requirements of performance and energy efficiency. There is a trade-off between operations and design in an automatic small parts store. A modern storage and retrieval crane has to provide a better performance without deteriorating the cost advantage and the storage capacity. An increase in the performance requires higher driving dynamics of the storage and retrieval crane, which requires a larger volume and a stiffer supporting structure to give a reduced calming time. This however leads to a deterioration of the approach dimensions and a reduced storage capacity. With the same volume of the supporting structure, the stability without changing the approach dimension can be implemented by an antipedalgear. This however leads to higher acquisition costs and reduced availability caused by an additional technical expense. Similarly the stiffness can be increased due to the lightweight construction with new materials, like Carbon Fibre Reinforced Plastic (CFRP). So the energy consumption as well as the stress of susceptible components will be reduced, what leads to a reduction of the operating costs and the availability. The acquisition costs will be significantly higher  using CFRP. The evolution of familiar concepts , which rely on the use of thin-walled, edged or rolled metal structures, are reaching their limits with an increase of dynamic. This shows, for example when there are problems with the fatigue strength and results in cracks in the metal. This is why GEBHARDT decided to go a revolutionary way and rely on composite materials. The result is the GEBHARDT Cheetah.

Up to now the implementation of a consistently lightweight construction with composite materials failed because of the high material- and manufacturing costs. That’s why the implementation of the Cheetah-mast is made of standard profiles of composite materials. The critical buckling of the large volume mast can be prevented with the use of profiles in the thrust range of the mast. The storage and retrieval crane is made of different materials, mainly steel, aluminum and composite materials. This material mix breaks down the previous problems with composite material concepts in storage technology.  Because the adhesive bonding has proved to be a good joining technology for different materials, a suitable surface pretreatment and  adhesive technique was developed. Equally the adhered materials were checked regarding their aging, to guarantee a permanent bond. Adhesive Bonding is especially advantageous in comparison to welding, because there is nearly no thermal deformation which has to be corrected. Also the adhesive is using the complete contact surface of the joining members – e.g. in comparison to spot-welding. Furthermore the adhesive gives a higher damping to the overall structure, so the storage and retrieval crane gets an improved calming time after slowing down. Besides the development of the new product, Gebhardt also had to implement new technologies for the manufacturing process. Up to now the multi material mix and especially the use of composite materials were used rarely in intralogistics. To check the operational stability and the operational safety of the new storage and retrieval crane, the mast was tested on a servo-hydraulic vibration test rig. It proved it’s stability even after a few millions of load change and showed no damage at all. Testing also included tens of thousands of collisions with the buffer and emergency stops. That’s how the test stand trials and aging test reflect the whole life cycle of the Cheetah.