Hybrid laser-arc welding of laser- and plasma-cut 20-mm-thick structural steels

It is already known that the laser beam welding (LBW) or hybrid laser-arc welding (HLAW) processes are sensitive to manufacturing tolerances such as gaps and misalignment of the edges, especially at welding of thick-walled steels due to its narrow beam diameter. Therefore, the joining parts preferably have to be milled. The study deals with the influence of the edge quality, the gap and the misalignment of edges on the weld seam quality of hybrid laser-arc welded 20-mm-thick structural steel plates which were prepared by laser and plasma cutting. Single-pass welds were conducted in butt joint configuration. An AC magnet was used as a contactless backing. It was positioned under the workpiece during the welding process to prevent sagging. The profile of the edges and the gap between the workpieces were measured before welding by a profile scanner or a digital camera, respectively. With a laser beam power of just 13.7 kW, the single-pass welds could be performed. A gap bridgeability up to 1 mm at laser-cut and 2 mm at plasma-cut samples could be reached respectively. Furthermore, a misalignment of the edges up to 2 mm could be welded in a single pass. The new findings may eliminate the need for cost and time-consuming preparation of the edges.

A Statistical Approach in the Analysis of Geometrical Product Specification during the Cold Tube Drawing Process

Cold tube drawing provides higher accuracy compared to hot approaches. The process can be used to reduce the dimensions of tubes, and depending on the reduction size, the wall thickness of these may be subject to changes. In the process, any form of variability provoked by external factors is highly sensitive, given that the resulting tubes are often the final step in tube production. This paper focused on the evaluation of the influence of pre-tube factors on key variables after the drawing process, i.e., the final roundness, outer diameter, and wall thickness of the tubes. For these purposes, a factorial design with fixed factors was implemented. It was also a goal to investigate if the single-pass type of drawing would guarantee good statistical results potentially leading to significant time and financial reductions. The measurements were executed in the machine ZEISS CenterMax. The statistical analysis took place on Minitab 19. The results prove that most factors, and their interactions, significantly impacted the response variables, leading the authors to understand that a single-pass approach would not properly work under the conditions defined for the experimentation. These results also allow for reflection on the causes and necessary measures related to lubrication, technological heritage, and quality that would impact the results themselves.

Challenges in Predictive Modeling of Single Pass Tangential Flow Filtration for Continuous Biomanufacturing

Opportunities for process intensification and increased productivity have made the field of Continuous Biomanufacturing an area of high interest and active research. Within the purification train of producing biologics, Tangential Flow Filtration (TFF) is typically employed after chromatographic separations, to increase drug substance concentration, making the process more economical and further meeting dosage specifications. In a batch operation, concentration occurs via recirculation of the feed material where desired output concentration is attained through multiple pump-passes over the TFF membrane, while steadily excluding the buffer. Single-Pass Tangential Flow Filtration (SPTFF) enables continuity of this process by achieving similar concentration factors through a single – pass over these membranes while operating at low feed flow rates. Our work elucidates the development of a mechanistic process model to predict SPTFF performance across a relatively wide design space using a first principles approach. The developed model is found to be accurate for a range of high feed flow rates but is inaccurate at flow rates below 25 L/m2/hr. At very low flow rates, small differences in the mass transfer coefficient have been observed to significantly alter the prediction of the retentate concentration. We thus describe the challenges in predictive process modeling of SPTFF in antibody biomanufacturing.

Conceptual design of the Hybrid Ring with superconducting linac

The Hybrid Ring with a superconducting-linac injector as a highly flexible synchrotron radiation source to enable new experimental techniques and enhance many existing ones is proposed. It is designed to be operated with the coexistence of the storage (SR) bunches characterized by the performance of the storage ring, and the single-pass (SP) bunches characterized by the performance of the superconducting linac. Unique experiments can be performed by simultaneous use of the SR and SP beams, in addition to research with various experimental techniques utilizing the versatile SR beam and research in the field of ultrafast dynamics utilizing the ultrashort pulse of the SP beam. The extendability of the Hybrid Ring will allow it to be developed into a synchrotron radiation complex.