This paper analyzes the impact of 3D model annotations on CAD user productivity in the context of the New Product Development Process. These annotations can provide valuable information to support an improved design intent communication. Comparably, they can play the same role as source code comments to support code maintainability in software engineering. A 3D CAD model is a geometry representation and it also stores the modeling strategy used to build it. Alteration of a complex CAD model usually represents a time consuming task due to the lack of an explicit explanation of the design rationale followed to build that 3D model. An experimental study conducted with Spanish and Mexican CAD students indicates that it is possible to reduce the time needed to perform engineering changes in existing models by between 13–26% by using annotations. Also some factors that affect the impact of annotations on the engineering change process such as part and alteration complexity were identified.
The microstructure of CrN/AlN films, prepared by reactive magnetron sputtering under various conditions, was analyzed and related to the wear behavior of the films. One set of films was prepared by conventional reactive magnetron sputtering, a second set adding an extra amount of reactive gas to the initial Ar + N 2 mixture and a third set adding an extra source of nitrogen near the substrate during sputtering. The samples were analyzed by scanning electron microscopy + energy dispersive microanalysis, high resolution scanning electron microscopy, atomic force microscopy, and x-ray diffraction. The results of the microstructural analysis revealed a clear difference in the morphology growth of the films when extra nitrogen was used compared to the conventionally prepared films. Formation of CrN was significantly faster than that of AlN. The most effective method to produce AlN was to introduce extra nitrogen. Pin-on-disk wear experiments were carried out in ambient air, to investigate the tribological behavior of the CrN/AlN system against a steel ball under dry conditions for various loads and a constant sliding speed. The results revealed that tribological properties of the layers improved unlike those of the untreated H13 steel. The friction behavior is closely related to the structure of the deposited films. The thicker CrN layer contributed to the higher load capacity of the coated steel when compared to the unmodified steel. However, wear life for the coating system was very short, denoted by the fairly poor adhesion of the film system to the steel substrate.
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