Toward a Digital Thread and Data Package for Metals-Additive Manufacturing.

Additive manufacturing (AM) has been envisioned by many as a driving factor of the next industrial revolution. Potential benefits of AM adoption include the production of low-volume, customized, complicated parts/products, supply chain efficiencies, shortened time-to-market, and environmental sustainability. Work remains, however, for AM to reach the status of a full production-ready technology. Whereas the ability to create unique 3D geometries has been generally proven, production challenges remain, including lack of (1) data manageability through information management systems, (2) traceability to promote product producibility, process repeatability, and part-to-part reproducibility, and (3) accountability through mature certification and qualification methodologies. To address these challenges in part, this paper discusses the building of data models to support the development of validation and conformance methodologies in AM. We present an AM information map that leverages informatics to facilitate part producibility, process repeatability, and part-to-part reproducibility in an AM process. We present three separate case studies to demonstrate the importance of establishing baseline data structures and part provenance through an AM digital thread.

Direct-reading color-difference meter based on cube-root color coordinates.

This paper describes a new instrument, based on the cube-root system of color coordinates, which reads color-difference coordinates directly. Silicon photovoltaic cells are used with glass filters to produce electrical signals proportional to tristimulus values. Tristimulus signals from a reference and a sample are converted to coordinate differences by means of simple, solid-state circuitry. Because operation of the instrument requires no mechanical adjustment or data entry, a color difference can be measured in about 15 sec. Excellent precision and stability have been demonstrated.

The silicon solar cell as a photometric detector.

Early in their development, silicon solar cells were recognized to have characteristics desirable for photometric detectors. It is therefore surprising that their use in this way has not become more widespread. Results of an investigation to establish more completely the photometric capabilities of these cells are presented in this paper. An equivalent circuit model is used to predict performance from basic cell parameters and the dependence on illumination level and load impedance is established. When load impedance is low, silicon cells have a small temperature coefficient and the cell current is accurately proportional to illumination. With high impedance loads and high illumination levels, the cell voltage is logarithmically related to illumination and the temperature sensitivity is approximately an order of magnitude greater. Variation of spectral response between unselected cells from the same manufacturer was found to be considerably less than that typically measured for unselected phototubes.