Summary A recent comparative vacuum technology study performed by Dr. Kingman Yee, as part of a DaimlerChrysler Summer Intern Professors Program, found that air consumption could be reduced by 98% when equipping a robot's end-of-arm tooling with COAX® technology and a Vacustat™ check valve. The study also estimated that if DaimlerChrysler were to replace its older, outdated vacuum systems, the company could experience an annual savings in air consumption costs of $418,300 per stamping plant (based on the use of 2,000 suction cups; does not include replacement costs.) Background As with most of today's global companies, DaimlerChrysler is constantly challenged to increase output while decreasing manufacturing costs. Additionally, the company prides itself on its commitment to sustainability and is always looking for new ways to use natural resources in a way that people's current needs are fulfilled without imposing limitations on the life-style of future generations. DaimlerChrysler has been able to significantly improve cost-efficiency through the increased use of robotic technology, particularly for automating material handling of sheet metal during automotive stamping applications, which involve moving sheet metal through a press or series of presses and forming it into a panel or other automotive part. As with all robotic applications, tooling is critical to the productivity. When handling metal pieces in automotive stamping applications it is particularly vital to have flexible tooling because changes in size occur each time the vehicle model or car part changes. One of the key components to the robotic tooling is the end effector, which accounts for "the hand" of the robot. In the case of sheet metal stamping applications, vacuum is used to pick up the metal sheet and transport it to the next destination. Robots, with their ability to use a variety of end-of-arm tools [EOAT], provide the high-speed "pick and place" ability needed to meet ever-increasing demands on manufacturers for flexibility and productivity, replacing other slower and potentially error-ridden methods. Challenge: Improve Robotic Efficiency In order to further improve robotic system performance and thus, productivity, Dr. Kingman Yee, as part of a DaimlerChrysler Summer Intern Professors Program, researched manufacturing processes that would lower the costs of the company's material handling applications at its automotive plants in Michigan. The challenge was to lower the costs of material handling applications by decreasing air consumption, reducing downtime and improving the performance and cycle time of robots and other equipment using suction cups to lift and transport parts.
Solution: PIAB COAX Technology Reduces Energy Consumption and Increases Performance One of the vacuum systems tested in the study was COAX®, a new multistage ejector technology from PIAB, based on a multi-stage concept for creating vacuum with compressed air. By integrating the internal components of a multi-stage vacuum pump into a vacuum cartridge, COAX allows for a smaller, more efficient, more reliable and highly flexible technology. In side-by-side comparisons with competitive vacuum ejectors and suction cups, Professor Yee found that the patented multi-stage design of the COAX vacuum generators uses only 1.1 SCFM of compressed air per cycle, up to 78% lower than the less efficient single-stage vacuum generators from other vendors. More significantly, PIAB's COAX technology can be equipped with a Vacustat™ check valve, which shuts off the supply of compressed air when proper suction is reached. If the vacuum level drops due to leakage, the pump will turn on briefly to return the vacuum to the desired level. Dr. Yee reports that simply by installing this Vacustat device, compressed air consumption can be reduced by an additional 98%. As a result, the cost to DaimlerChrysler for the electricity to produce the compressed air for a single suction cup is $0.56 per year, compared to at least $61.66 per year per suction cup for the latest systems available from the other vendors (based on an electricity cost of $0.07 kW-hr). For a typical automotive stamping plant employing 2,000 suction cups, the savings is $122,200 per year. If DaimlerChrysler were to replace older, outdated models still in wide use, Professor Yee estimates that the annual savings will be $418,300 for that typical stamping plant. (This figure is based on the use of 2000 suction cups does not include replacement costs). The modular construction of the COAX system facilitates quick and easy maintenance, repair and replacement of the vacuum components and suction cups. For the comparative systems, the entire vacuum assembly and its suction cups must be removed or replaced if it malfunctions. This process causes significant downtime, which can be detrimental to the productivity of the entire plant. "The multi-stage design of the COAX ejectors enhances material handling performance by producing superior vacuum flow and responding almost immediately when compressed air is applied," said Yee. The COAX ejectors achieve an evacuation flow rate of 85 SCFH and produce a holding force of 100 lbs, which is 25% higher than the competitors' solutions, according to Yee. The quicker response and better vacuum flow means the suction cups grab quicker and hold stronger, resulting in a faster process cycle time, and higher productivity. Dr. Yee's study also reports that the PIAB vacuum solution improves the work environment by decreasing noise. The COAX ejector is appreciably quieter both during load and no-load conditions. Moreover, the Vacustat check valve significantly lowers noise and practically eliminates the "hiss" associated with typical suction cup systems. "Because of the numerous advantages and significant cost savings in air consumption offered by the PIAB vacuum system," Dr. Yee's report concludes that "it is recommended that the PIAB system be increasingly incorporated into DaimlerChrysler's plants." ### About Kingman Yee, Ph.D. Dr. Yee is an Associate Professor of Mechanical Engineering at Lawrence Technological University (LTU) in Southfield, Michigan. Dr. Yee holds a Ph.D. in Chemical Engineering, with a specialization in the study of electrodeposition processes in flow batteries used in electrical vehicles and load leveling. Prior to joining LTU, Dr. Yee worked at BASF Inmont Automotive Coatings and General Motors Research Laboratories and has performed research in manufacturing laboratories in Singapore. He has also consults at DaimlerChrysler Corporation, researching and implementing cost-saving innovations in manufacturing.
