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- PublicationTool Wear in Milling of Medical Grade Cobalt Chromium Alloy - Requirements for Advanced Process Monitoring and Data AnalyticsComputer Aided Design (CAD), Computer Aided Manufacturing (CAM) and Computer Numerical Control (CNC) are platform technologies in high end manufacturing. However, the machining process on the CNC Machine Tool is generally the main source of loss of component accuracy, precision and extraneous effects on surface finish and integrity. Moreover these 'losses', and therefore costs, only increase in cutting processes due to the inherent modes and mechanisms of progressive and catastrophic tool wear. In high end manufacturing sectors, these losses are also exacerbated by the use of 'difficult-to-cut (DTC)' materials while more stringent specifications apply and higher levels of process capability are demanded. The use of Cobalt Chromium (Co-Cr-Mo) alloys in the Medical Device sector is indicative of the many challenges. However, notwithstanding the importance of the application, there are few publications on the fundamental mechanisms in cutting this alloy, other than by the present authors. This paper builds on our research to date by reporting some preliminary results on tool wear progression in CNC milling of the Co-Cr-Mo alloy conforming to ASTM F75. It also assesses the feasibility of real time tool wear monitoring on a Mori Seiki NMV1500 CNC Machining Centre using the MTConnect communication standard. The results obtained through MTConnect are provided by embedded sensors within the machine tool and are correlated with a laboratory piezoelectric dynamometer. The results from both methods, obtained at two cutting speeds, are also related to observed tool wear progression and the cumulative volume of material removed. The results are discussed in terms of the potential and limitations of using of MTConnect and the machine tools embedded sensors, for monitoring of the process and the onset of tool wear.
- PublicationInvestigation of process by-products during the Selective Laser Melting of Ti6AL4V powderThis paper investigates the formation of process by-products during the laser processing of titanium alloy powders by Selective Laser Melting (SLM). The study was carried out during the printing of Ti6AL4V parts using a production scale SLM system (Renishaw RenAM500 M). By-product particles were obtained on the surface of powder removed from the area around where the pulsed laser powder treatments had been carried out. The process by-products examined in this study were damaged Ti6AL4V particles along with condensate. The particles were found to exhibit deshelling, fracture, and collision damage. Based on TEM and SEM examination, the condensate particles were found to have sizes in the nanoscale range and exhibited morphologies, similar to those reported in the literature for welding condensates. Energy-dispersive X-ray spectroscopy (EDX) analysis indicated that the condensate formed from processing Ti6AL4V, exhibited a higher level of aluminum than that obtained for the alloy itself, lower levels of titanium with minimal vanadium levels, were also obtained. This may indicate that the alloy partially decomposes, with the emission of the lower melting point alloying element. The use of an in-situ melt pool monitoring system (called Renishaw InfiniAM Spectral), was evaluated for detecting the presence of these by-product particulates, based on photodiode measurements of the melt pool emissions, along with a camera-based imaging of visual per layer conditions. A reduction in the intensity of infrared emissions was detected, in areas where suspected spatter particles had been redeposited. Thus, demonstrating that process monitoring can be used for the in-situ detection of particulate defects formed during printing.
Scopus© Citations 20 191
- PublicationApplication of Additive Manufacturing in Design & Manufacturing Engineering EducationThis paper details how education and training in both digital manufacturing and materials processing was implemented as part of an undergraduate engineering programme involving 90 students. The programme was provided through additive manufacturing (3D printing), which enabled the students to develop an understanding of part design, fabrication and performance. The 3D printing study was carried out using Fused Deposition Modelling (FDM) and involved the fabrication of a turbocharger turbine part. This was subsequently evaluated using a customized test rig to assess the printed turbine rotation speed, under a fixed air-flow. The dimensions and morphology of the fabricated parts were also evaluated. Students benchmarked the performance of their turbine parts, against the part which was found to exhibit the highest rotation speed. A pre- and post-course survey was conducted to track the learning experience and feedback from the students involved. The results demonstrated that incorporation of digital manufacturing, self-guided and peer learning improved the engagement and learning experience.
Scopus© Citations 10 103