Table of contents:
- Moving or holding a workpiece?
- Picture gallery
- Take a close look at the grippers
- It depends on the application
Video: An Exact Comparison Of Electrical And Pneumatic Drives
The question of whether a pneumatic drive is more energy efficient than an electric one or vice versa cannot be answered straight away. "Energy efficiency in automation technology always depends on the respective industrial application," explains Roland Volk, energy efficiency consultant at Festo. Only the direct comparison of two equally sized drives - one electric and one pneumatic - in different tasks clears up prejudices.
First of all: The truth, which is the most energy-efficient drive, lies as always in the middle. Energy efficiency is entirely dependent on the task at hand on the drive. The measurements reveal the following differences: With a simple movement task, the electric drive is cheaper. For press-in processes, the amount of process force and the duration of the process determine the more efficient technology. However, if the application requires holding forces, the pneumatics have a clear advantage.
This is what the drive technology of the future looks like
Moving or holding a workpiece?
In this comparison, movements from point A to point B are carried out. These movements can almost exclusively be carried out by pneumatic drives. Nevertheless, electric drives are often used to implement such simple movements. If the task of free and flexible positioning is required, electric drives have an advantage.
This results in very different energy consumption. When moving the drives without additional process power, the electric drive with 25 Ws only uses a third of the energy that the pneumatic one requires (78 Ws). In the task of “pressing with process power”, both drives are roughly the same with an energy consumption between 20 and 30 Ws.
On the other hand, if the drives have to hold a certain position, the energy consumption of the electric drive skyrockets to 247 Ws. This is more than 22 times as much as the energy consumption of the pneumatic drive (11 Ws). The pneumatic drive benefits from the fact that it only needs energy for the brief moment of compressed air build-up. The holding process itself does not require any new compressed air and therefore does not cost any energy. The electric drive, on the other hand, requires permanent electricity to remain in the selected position. The longer the holding process, the higher the energy consumption of the electric drive compared to the pneumatic one. According to measurements, small leaks have practically no influence on the low energy consumption.
Picture gallery with 5 pictures
Take a close look at the grippers
The comparison between electric and pneumatic grippers produces similar results. The comparison shows how dependent the right solution is on the clear definition of the task. Considering the energy consumption during the gripping process, the pneumatic gripper is superior to the electrical one if the application involves long cycles and only a few gripping processes.
The pneumatic gripper only needs pressure once to hold it permanently. No further pneumatic energy is required for the duration of the gripping. The electrical gripper, which requires electrical energy for the entire duration of the gripping, can only be more energy-efficient than the pneumatic one if the application consists of short cycles with a large number of gripping processes.
The book "Practical Manual Drive Design" helps in the selection of the essential components of electrical drive systems: motor, gearbox, actuator, mains supply and their additional components. The calculation is also dealt with intensively.
It depends on the application
Every industrial application has its own specific requirements for technical criteria such as speed, resilience, power-to-weight, accuracy, control behavior, load stiffness, efficiency or robustness as well as economic criteria such as the necessary acquisition costs (price, commissioning and installation) but also the resulting operating costs (including Maintenance, lifespan and energy costs).
Depending on the application, energy efficiency is a question of the task. "This task must first be clearly defined before the user chooses the drive technology - electrical or pneumatic or a mixture of both," explains Roland Volk. A technology comparison can only be made on the basis of the total cost of living (TCO), which takes into account both the acquisition costs and the energy expenditure.
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