Posted to News on 13th Apr 2010, 17:14
OVEM vacuum generator module uses less energy
Festo is launching the OVEM vacuum generator module that benefits from built-in energy-saving and condition monitoring functions. One of the key features of the OVEM vacuum generator is an integrated vacuum sensor that continuously monitors the output; the module operates until a user-defined vacuum threshold has been reached, then it switches off automatically - resulting in significant energy savings. A built-in non-return valve ensures that, in normal use, vacuum loss is limited to air leakage between the suction cup and the workpiece. The generator is turned on again automatically if the vacuum drops to another user-defined threshold.
Festo's OVEM vacuum generators use the Venturi principle, employing a de Laval nozzle to accelerate airflow across the top of the evacuation tube. They are designed for use with standard 40um filtered compressed air supplies, with efficiency-optimised flow characteristics to reduce energy consumption. The generators are available in versions optimised for high vacuum or high suction, and offer a choice of 5, 7 and 10mm de Laval nozzles to accommodate a variety of vacuum flow rates and workpiece porosities. Being protected to IP65 means that the vacuum generators can also be mounted close to the point of operation, despite their built-in 'intelligence.'
Condition monitoring
As well as helping to save compressed air, the OVEM generator's vacuum sensor provides continuous system monitoring and diagnostic functions. Any gradual or sudden loss of vacuum, or any lengthening of vacuum evacuation time, is detected automatically and a signal fed back to the system's controller. This data can be used for preventive maintenance purposes so as to minimise machine downtime and ensure process reliability.
All user-defined operating parameters - including upper and lower vacuum thresholds, normal vacuum evacuation time and overall system cycle time - are set using the pushbuttons and LCD screen on the front of the module. The backlit four-character alphanumeric LCD features analogue and numerical displays that enable the relative pressure or vacuum to be seen at a glance. Users can choose to display the vacuum level in inches of Mercury, inches of water or bar.
Ejector function
The OVEM vacuum generator module features two fully integrated solenoid control valves: one is for switching the compressed air supply on and off to generate the vacuum, while the other activates an ejector pulse. The ejector pulse helps to reduce cycle times by quickly dissipating the vacuum when the generator is turned off, enabling the workpiece to be released using a quick 'blip' instead of having to wait for the suction cup and associated air pathway to return to atmospheric pressure. A flow control screw is provided for adjustment of the ejector pulse flow.
Festo says its OVEM vacuum generators are very easy to install and maintain. All pneumatic connections employ push-in QS fittings and electrical connections are made via a five-pin M12 plug. The solenoid valve for vacuum on/off can be controlled by a normally-closed or normally-open switch, and there is a choice of six different configurations for the vacuum sensor's electrical switching output to further simplify system integration. The generators require very little maintenance; an open silencer and integrated air filter prevent contamination, and a viewing window facilitates filter inspection without having to disturb the module.
Venturi-based vacuum generators can be extremely effective at reducing cycle times and enhancing operating reliability. However, to ensure that they are energy-efficient they need to be selected according to the demands of the application; the size, mass and porosity of the item to be picked, as well as the forces resulting from the planned movement, are all factors that influence this choice. Festo's vacuum selection software is now available free of charge to simplify the process.
Follow the link for more information about Festo's OVEM vacuum generator module.
