Multiple Ndt Methods in the Automotive Industry

The automotive industry must meet the requirements for increased safety (product liability), stricter regulations regarding environmental protection, as well as the demands of car drivers for more luxury features. Costly recall actions, ever increasing demands on the quality management and the changing legal framework with a simultaneously harsher competition force the industry towards a more economic direction. Improved accessories for vehicles lead to increased weight. Higher weight also means higher gasoline consumption. This is only one of the reasons for today’s “lightweight design“ of new vehicles. Whereas steel was with more than 80 percent the most important material for the automotive industry in the past, other materials such as plastics, magnesium and aluminum will become more important in the future. The use of several materials will inevitably lead to new joining techniques since the traditional joining techniques, e.g. spot welding for body constructions, can only be partly used. A combination of methods will replace a single dominant method in the future. Due to the changed conditions with regard to material and joining technique, quality assurance must likewise adapt itself to the changes in production conditions. New test techniques are not only meant to determine the current quality of a bonded joint but also more and more to positively influence the whole process by corresponding measured variables. The industry will have to invest in safety and quality in the future as well because the conditions related to product liability will continue to cause recall actions and other cost-intensive measures. Advanced processes will be in demand, measured by (NDT) variables in the field of quality management. The lecture sheds light on feasible solutions in the automotive industry (e.g. quality inspection of joining techniques in car body framework and of casted components) using various methods (ultrasonic, x-ray etc.) and the resulting benefits for the users. References: W. Roye “Nondestructive Inspection Methods in the automotive industry”, 8 ECNDT Conference, Barcelona (Spain), June 17-21, 2002 Spot welds The computer aided spot weld inspection, see Figure 1, has achieved a high state of the art and is applied by almost all car manufacturers. Here, the principle is briefly discussed, see Figure 1: n Figure 1: Spot Weld Inspectio Figure 2: The principle of spot weld inspection In the case of a good spot weld [1] we obtain an echo sequence as shown. Due to the coarse grained material and the related sound attenuation the echo sequence decays quickly. 1 2 If the spot is too small [2], the echo sequence contains intermediate echoes due to the fact that the sound field diameter is larger than the spot diameter. 3 A stick joint [3] is transparent for the sound but the lower sound attenuation leads to a longer echo sequence. Finally, if there is no bonding [4], one obtains an echo sequence from the first plate only. 4