Replacing conventional vacuum ejectors with high-performance versions brings savings in compressed air, energy costs and downtime at a major carmaker
Consideration of the economic and efficiency aspects of vacuum gripping systems for handling sheet-metal parts are of enormous importance, particularly in the automotive industry.
A basic distinction can be made between centralised and decentralised vacuum generation. For centralised generation, for example, with compact ejectors that have integrated vacuum monitoring and valves, the so-called “air-saving function” has been the state of the art for many years now. This air-saving function – switching off the compressed-air supply when a defined vacuum level is reached – is extremely important if the high costs for this medium are to be reduced.
In many cases, however, it is forgotten that the cost reductions for compressed air in press shops and bodyshell assembly are only a part of the possible cost savings, and that far greater potential savings are being ignored. Typical “cost-eaters” are tooling errors or vacuum leaks in the gripping systems that are very difficult to identify and localise. Such problems result in idle times or, in the worst case, to an uncontrolled stoppage of the system – a crash. And it goes without saying that such events cause very high costs.
Schmalz in Glatten, Germany, a world market leader in the area of vacuum technology for the automotive industry, considered how these large cost-generators can be avoided and developed new vacuum generators with a special “Condition Monitoring System”.
A well-known German-American car manufacturer was convinced by the benefits of the new generation of Schmalz vacuum generators for a press line in which several presses are linked together by robots. This press line runs in three shifts and produces various bodyshell parts made of sheet steel and aluminium, and it is thus frequently necessary to convert the line several times during each shift. The company wanted to use new vacuum generators for this press line, and these had to be faster, more efficient and more fault-resistant than the previously used ejectors.
Since the various vacuum spiders were frequently affected by faults, which resulted from wear and tear and caused very high costs, the company was looking specifically for a solution which would improve the process reliability.
They found the solution in the form of the highperformance ejectors of the type X-Pump from Schmalz.
These X-Pump ejectors are characterised, on the one hand, by their extremely high suction and blow-off power (30 per cent higher than conventional compact ejectors with the same nozzle size), their very fast generation of high vacuum levels (0.05 seconds), their very short reaction times and their compact and light design. These properties made very short cycle times possible (>8 parts/minute although the presses are positioned 8 metres apart), resulting in considerable improvements in the productivity and efficiency of the complete press line. On the other hand, the high-performance ejectors X-Pump are designed as integrated compact units and include both air-saving and condition-monitoring (diagnosis) functions.
The integrated condition monitoring functions offer further benefits that are decisive for the user. They permit major improvements in the availability and thus in the process reliability of vacuum gripping systems used for handling sheet-metal parts. Defects in the system – vacuum leaks – are indicated even in the idle positions of the presses (suitable indicator lamps display the current status of the vacuum gripping systems), which means that preventative maintenance can be carried out during the next set-up phase of the press line.
This technology makes it possible to completely eliminate faults that result from the gripper-tooling or from wear and tear.