MechChem Africa talks to Skye Prato, Industry Sector and Business Unit Manager at Festo about how to improve the energy efficiency of automation systems and the need for all manufacturers to put sustainability at the heart of their operations.
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Skye Prato has been with Festo South Africa for over 20 years in various technical and sales positions. “I am currently the Head of our Business Units for Process Automation (PA), Electric Automation (EA) and industry segments such as automotive, food and packaging and the process industries,” he tells MechChem Africa.
“Festo core products are pneumatic actuators such as cylinders, actuated by pneumatic valves using compressed air; and the rapidly advancing range of electromechanical actuators driven by stepper or servo motors using a mechanical spindle, tooth belt or rack and pinion to convert the rotating motion into linear movement.
“Our actuators are supported by a full range of automation control products: Programmable Logic Controllers (PLCs) with full Computer Numerical Control (CNC) functionality built-in, HMI touchscreens for operators, SCADA systems, Artificial Intelligence (AI) and machining learning systems for the modern Industrial 4.0 factory,” he explains.
Pneumatic actuators are simple to manage, very cost-effective and they come with significant advantages. “For example, when a cylinder gets to its full forward position, it stops by itself. Also, once fully forward – assuming there are no air leaks – a cylinder can, in theory, hold a clamp secure under pressure indefinitely, without consuming any further energy. It only consumes energy while moving,” he notes.
This makes pneumatics ideal where clamping, gripping and holding periods are long as compared to release and retract periods. However, it is generally less expensive to use electrical equivalents for very short cycle times and brief holding periods,” he adds.
“Two really important factors are now driving the adoption of electrical actuators in automation systems. The first is cost, and the other is, of course, to save the planet. Current energy use is consuming resources on our planet that we can't replace. These two key factors are driving manufacturers all over the world to reduce costs while improving sustainability and energy efficiency.
Improving the energy efficiency of pneumatic systems
The best time to consider energy efficiency, according to Prato, is when a production project or an application is new and by planning for efficiency upfront rather than as an afterthought. To achieve this, manufacturers and plant operators need to align with suppliers that can offer the most up-to-date products and expertise.
Once installed, it is vital to maintain those systems, and this is particularly crucial when it comes to pneumatics. “Pneumatics is still generally the most efficient and simplest way to clamp, hold, push and lift objects in industry. However, it is only efficient if these systems are properly maintained. Imagine having an electrical panel with sparks jumping out of it or a hydraulic hose with oil leaking out. These faults would be dealt with immediately.
“But when it comes to a pneumatic system leaking air, it is not perceived as dangerous and is often just ignored. This is a huge problem with respect to energy efficiency. Pneumatic systems need to be maintained.” Skye Prato explains.
Describing some other Festo innovations to improve pneumatic system efficiency, he says that the first involves reducing energy consumption on the reverse stroke. “For most pushing, clamping, holding and lifting applications in industry, the pneumatic actuator is only required to apply force in one direction. On the return stroke, there is very little load requirement, yet in 99.9% of applications, the same pressure is used in the forward and return directions,” he explains.
Festo has developed a valve terminal called a Motion Terminal VTEM that automatically reduces the pressure on the return stroke of a cylinder. “In a 6.0 bar clamping application, we can save 30% of the energy used by the system by simply reducing the return pressure to, for example, 1.0 bar. The motion terminal is digitally controlled using piezo-electric valves, so there are no implementation complications,” he says. Further to this, the VTEM has an ECO Drive App that automatically manages the forward and return pressures to achieve energy savings of around 70%.
“Our VTEM is the world's first digitised pneumatic valve to be controlled by apps, which enables functional changes to be made on the fly by the PLC or controller. This makes for a highly flexible system from a standardised product range, offering flexibility, simplicity and energy efficiency,” Prato adds.
Turning attention back to managing air losses and quickly detecting leaks in pneumatic systems, he cites another innovation: the MSE6 family of pneumatic service units. These are electronic energy-efficient modules for conditioning, regulating, switching and measuring the compressed air supply into the pneumatic systems of a machine. The MSE6 module is an intelligent service unit with built-in sensors and Fieldbus communication. “The unit is able to continuously monitor compressed air consumption and shut off the supply when it detects that the machine is not in use,” he explains, adding that this minimises the natural air losses that would arise while the machine is not being used. “More importantly, the MSE6 transmits status data to the PLC, on air and energy consumption for tracking, benchmarking and comparing the efficiency of each machine in use. This is a powerful tool for energy efficiency optimisation,” he says.
This saves money, reduces compressed air consumption and energy costs, enabling the manufacturer to reduce its carbon footprint and improve sustainability. “It is also a simple way for a facility to start its Industry 4.0 journey, adding transparency, data analysis, trending, artificial intelligence and machine learning capabilities to better manage and improve operational performance,” notes Prato.
“Our MSE6 can actually pick up that one cylinder out of 20 is leaking in a system, which can be used to generate an immediate notification of energy losses. This enables rapid problem diagnosis and repair times.”
Electric actuators
Describing the key advantages of electrical actuators, Prato notes that they offer much better speed and positioning and can be accurately controlled. “While generally more expensive in terms of initial costs, switching to electrical actuation can be far less expensive in the long term because of its better efficiency for short cycle and holding times,” Prato continues.
“Festo has been developing and supplying an electrical actuator range for over 16 years. We now have third and fourth-generation electrical actuators, so this is not a new field for us. In recent years, it has become more of a significant and transformational focus for us,” he says. He further adds that with the energy-efficient products Festo has developed over time, there is now a wide range of excellent equipment available.
He cites an implementation example for a large machine builder in South Africa. “The company was making ‘bag-in-a-box’ dispensing containers for liquids: such as the 5ℓ boxes of wine and juice with a bag and tap inside.
“A machine 20 or 30 metres long is used to make the bags, which have multiple layers of plastic/foil welded together. Layers of plastic/foil are rolled off, a tap is inserted, and the shape is formed by melting the layers together to create a square bag – all at high speed,” he explains. “Two-metre heated sealing bars, traditionally controlled with pneumatic cylinders, were being used to clamp down onto the plastic and fuse the layers. The three variables needed to successfully weld and seal these seams are pressure, heat and duration. Besides the heat, it was the pneumatic cylinders continually pumping up and down at high speed to seal the bags that were consuming big energy – and there were a lot of them.
“So we did some theoretical calculations based on replacing most of the pneumatic actuators with electrical ones from Festo. We found that an electrical solution would require only 10% of the energy that the fully pneumatic system consumes.
“Another benefit is that the machines are pretty silent. There is no longer any noisy exhaust air coming from the 60 to 70 actuators cycling at high speed,” he adds.
“Yes, we love pneumatics. Yes, it's simple. Nonetheless, we have to consider other technologies as well, and sometimes a combination may be the better choice. This ‘bag-in-a-box’ machine still uses some pneumatic actuators, but the bulk of the sealing and cutting bars have been converted,” he tells MechChem Africa.
“To achieve energy efficiency for any automation system, it is essential to get expert advice on each of the technologies used in the design,” he advises. “Festo develops and sells both pneumatic and electric automation technology and we give unbiased advice on the most cost-effective, energy-efficient and sustainable combination of technologies to use for any application,” Skye Prato concludes.