Posted to News on 17th Jun 2008, 14:53
Vacuum generators help to reduce machine cycle times
Festo is launching a series of modular venturi vacuum generators that use integrated electronics to help maximise operational efficiency. Offering an exceptionally wide choice of configuration options, the company's latest-generation VN series vacuum generators provide machine builders with a very flexible and cost-effective means of facilitating the movement of workpieces in pick-and-place systems.
VN series vacuum generators are suitable for a broad range of light industrial applications, including packaging, pharmaceutical and electronics manufacturing, and general precision engineering. They are small, lightweight units that can easily be installed in the gripping zone, making them useful for automation systems employing decentralised control architectures. The vacuum generators are also particularly suitable for applications involving fast cycle times - their efficiency and placement flexibility help minimise air path evacuation times.
All VN series vacuum generators are designed to operate from standard 1-8bar compressed air supplies, and offer a choice of -0.85bar high vacuum or -0.5bar high suction models - the latter provide extremely fast evacuation times. They are all available in standard "T' and "inline' mounting configurations, with a choice of Quick Star push-in or threaded connections. The vacuum generators use de Laval nozzles to accelerate airflow across the top of their venturi vacuum tubes. For maximum efficiency the nozzle needs to be optimised to suit the vacuum flow rate and the porosity of the material that is being handled, so Festo offers a choice of six nozzles, ranging in size from 0.45-3.0mm.
Optional integral solenoids
Festo's VN series vacuum generators are optionally available with integral 15-30V DC solenoid valves for fast vacuum on/off control, and with a mechanical ejector pulse function that quickly dissipates the vacuum when the generator is turned off, thereby ensuring reliable release of the workpiece from the suction cup and thereby help reduce cycle times.
The VN-P models also optionally feature a fully integrated piezoresistive pressure sensor, which provides a very useful process monitoring function; the sensor's threshold comparator can be set to have either fixed or variable hysteresis, based on two pressure values that are acquired using a "teach-in' pushbutton on the body of the unit. When the applied vacuum reaches the preset pressure, the workpiece is regarded as gripped; if it is more than the preset, the workpiece is regarded as not fully gripped and is therefore flagged as unacceptable. Using the window comparator mode, the lower pressure value can be employed to indicate safe workpiece handling, while the higher pressure value can control vacuum switch-off thereby turning off the airflow until the vacuum level rises. This saves a significant amount of compressed air - up to 50 per cent in many applications.
All VN series vacuum generators are designed to operate from dried, filtered and unlubricated compressed air. As standard, the vacuum generators are supplied with high-efficiency, maintenance-free open silencers. These use a combination of sound absorption and reflection principles to achieve low flow resistance and high noise attenuation characteristics.
For more information, visit www.festo.com/cms/en-gb_gb/index.htm.
