Additive Manufacturing (AM) does not yet have a standardized way to measure performance. Here a AM machines dimensional accuracy is measured trough acceptance test (AT) and AM machines capability is tested trough test parts. Test parts are created with specific geometrical features using a 3D AM machine. Performance of the machine is then evaluated trough accuracy of test parts geometry. AM machine here uses selective laser melting (SLM) process. This machine has done Factory acceptance test (FAT) to ascertain this machine ́s geometrical accuracy with material AISI 316L. Manufacturer promises accuracy of ±0.05 mm. These parts are used as comparison to AT parts made in this study. After installation two AT parts are manufactured with AM machine. One with AISI 316L and one AlSi10Mg. Dimensional accuracy of geometrical features on these parts are then compared to FAT part and to one another. Machines capability is measured trough two test parts done with material AlSi10Mg. Two of the test parts are done at the same time using same model as the FAT. Parts are printed without supports and with features facing same directions. Features of these parts were then evaluated. Another test to find out AM machines capability was to create part consisting of pipes doing 90˚ angle resulting in horizontal and vertical holes. Dimensional accuracy and circularity of holes was measured. Through these tests machines capability is benchmarked.
This paper presents transistor measurements done at a constant temperature. The aim in this research was to develop a reliable and repeatable method for measuring and searching transistor pairs with similar parameters, as in certain applications it is advantageous to use transistors from the same production batch due to the significant variability in batches from different manufacturers. Transistor manufacturing methods are well established, but due to the large variability in tolerance, not even transistors from the same manufacturing batch have identical properties. Transistors' electrical properties are also strongly temperature-dependent. Therefore, when measuring transistor properties, the temperature must be kept constant. For the measurement process, a solid-core oven providing stable temperature was implemented. In the oven, the base-to-emitter voltage (VBE) and DC-current gain (β) of 32 transistors could be measured simultaneously. The oven's temperature was controlled with a programmable thermostat, which allowed accurate constant temperature operation. The oven is formed by a large metal block with an individual chamber for each transistor to be measured. Isolation of individual transistors and the highly thermally conductive metal core structure prevent thermal coupling between transistors. The oven enables repeatable measurements, and thus measurements between different batches are comparable. In this research study, the properties of over 5000 transistors were measured and the variance of the aforementioned properties was analyzed.
Metal 3D AM (Additive Manufacturing) has been becoming a more common production method for larger variety of parts. In this review the current situation and future development trends of the 3D metal AM are presented, concentrating on the SLM (Selective Laser Melting) technology. A holistic approach to the AM as a digital manufacturing method is presented and different manufacturing aspects of the AM production are identified. The most promising aspects for the future development are the automatization of the AM design tasks and automatization of the production. With the development of these aspects the production and cost efficiency of the metal AM can be increased to a more competitive level compared with other manufacturing methods.
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