Kvalitetssäkring av stordimensionella gjutgods : Produktion och kontroll av formgjutna komponenter

Sammanfattning: Abstract A continuous improvement of products and production is an important goal for a modern industrial company. A small engineering group located in Sweden came in touch with the authors of this report during the spring semester of 2014. The aim of this report is, as part of the group´s ambition of improvement, to analyse ways in which the quality of component casted parts can be verified. Non-destructive testing (NDT), and methods to use it for quality control, is the main focus of this report. However, fields such as material standards, component casting and quality engineering are analysed as well. Together, these fields act as the baseline of the conducted work. This thesis consists of two major parts; a theoretical, based on scientific literature, and an empiric, based on field studies and interviews conducted in cooperation with three Swedish foundries. The scientific literature that has been analysed does not correspond entirely with the practical reality of the foundries. The different opinion considering ultrasonic testing (UT) is an example of this minor disagreement between theory and pragmatic engineering. While several books and articles regard UT as efficient and reliable, the foundries consider UT a flawed and problematic testing method. The foundries are mainly troubled about the required level of education necessary for operating UT, which is way too high and thereby expansive for UT to be an affordable option. Cast iron materials are, as noted by the foundries, as well not an optimal environment for UT. The high amount of graphite in the cast iron interferes with the ultrasonic waves, resulting in non-accurate results of the ultrasonic testing. It can be concluded that NDT-method cannot compete with destructive testing, neither in performance nor cost, when used as a tool of quality verification of a component casted part. However, if it despite this is necessary to use NDT-methods, some conclusions can be drawn. Radiografic testing, magnet particle testing and penetrant testing can be considered the most suitable choice of NDT-methods when quality checking cast iron goods. Some relationships between the part’s size and the component casting process can as well be determined. The dimensions and mass of the component does not seem to have anything but a minor effect on the casting process. However, the complexity of the produced part’s geometry does have a major, negative, impact on more or less every step of the production. The analysed literature does seem to approve the foundries point of view considering the use and appliance of material standards. There is a noticeable trend throughout the industrial world, where old, national standard systems are replaced with international and global standardisation systems. However, continuous use of older designs without up-to-date standards does slow the progress down. While general systems of quality management may be applied within the component casting industry with decent results, the most important aspect of quality control is concluded to be a healthy and trustful business relationship between foundry and customer. Together, they are able to optimize products and production, and thereby guarantee a satisfying quality.