One Picture is Worth a Thousand Measurements
A large pool of measuring instruments is available to Bosch researchers for use in production and quality measurement. But these high-tech tools are not the last word: Efficient high-speed image processing of the accumulated data is the decisive factor affecting the quality of the measurement results.
The vernier caliper has become a thing of the past. The days have gone when a straightforward inspection of a component’s geometry using simple, mechanical measuring techniques was perfectly adequate. Today’s much more exacting requirements call for a whole array of measuring instruments to be integrated into production – invaluable resources that assure the high quality of Bosch products. What’s more, customers now demand 100-percent inspection of manufactured parts. Testing must consequently be nondestructive. These new methods make it possible to inspect internal, previously inaccessible surfaces, for instance in injectors, as well as exterior surfaces without damaging them.
Bosch Research is responsible for selecting suitable measurement methods and developing them to suit specific applications. These methods include computer tomography – known thanks to its use in medicine – as well as eddy current and ultrasound methods.
Innovative and unconventional developments are used as well. As an example, a microphone can be used to make tiny cracks in a surface audible: A stream of compressed air is directed at the test object. If the air encounters a crack, smooth airflow becomes turbulent – and the microphone measures the resulting fluctuations in air pressure. This turbulence sensor can detect pores and fissures in the surfaces of weld seams, plastics and castings.
Powerful, high-speed data and image processing is continuing to gain in importance. Today’s advanced techniques don’t just produce a measurement like the old-fashioned vernier caliper – but a mountain of information, which can be distilled into two or three-dimensional images. X-ray CT analysis of a single cubic millimeter of a material sample yields about two gigabytes of data. Data volumes like these have given rise to the concept of data mining: Special software is used to evaluate the data, suppress artifacts and selectively filter the significant parameters of the test object from the mountain of data.
High speed is particularly important in the quality control of laser welding. An injector has something like ten different weld seams. Welding the nozzle hole disc in place within the valve is particularly critical. Even the smallest material irregularities can result in imperfect seals, especially if a splash of material is ejected (see the sequence of images above). An event such as this lasts for just a millisecond and occurs only once a day, with a daily production volume numbering in the thousands. To catch this rare event anyway, a high-speed camera with special optics keeps looking directly into the glaring light of the weld point. When the welds are complete, the automatic image evaluation system checks and approves each produced item for delivery.
Bosch Research is responsible for selecting suitable measurement methods and developing them to suit specific applications. These methods include computer tomography – known thanks to its use in medicine – as well as eddy current and ultrasound methods.
Innovative and unconventional developments are used as well. As an example, a microphone can be used to make tiny cracks in a surface audible: A stream of compressed air is directed at the test object. If the air encounters a crack, smooth airflow becomes turbulent – and the microphone measures the resulting fluctuations in air pressure. This turbulence sensor can detect pores and fissures in the surfaces of weld seams, plastics and castings.
Powerful, high-speed data and image processing is continuing to gain in importance. Today’s advanced techniques don’t just produce a measurement like the old-fashioned vernier caliper – but a mountain of information, which can be distilled into two or three-dimensional images. X-ray CT analysis of a single cubic millimeter of a material sample yields about two gigabytes of data. Data volumes like these have given rise to the concept of data mining: Special software is used to evaluate the data, suppress artifacts and selectively filter the significant parameters of the test object from the mountain of data.
High speed is particularly important in the quality control of laser welding. An injector has something like ten different weld seams. Welding the nozzle hole disc in place within the valve is particularly critical. Even the smallest material irregularities can result in imperfect seals, especially if a splash of material is ejected (see the sequence of images above). An event such as this lasts for just a millisecond and occurs only once a day, with a daily production volume numbering in the thousands. To catch this rare event anyway, a high-speed camera with special optics keeps looking directly into the glaring light of the weld point. When the welds are complete, the automatic image evaluation system checks and approves each produced item for delivery.
