J. Manuf. Mater. Process., Volume 1, Issue 1 (September 2017) – 11 articles

Under the support of an SBIR Phase II/IIB grant from the National Science Foundation, OMAX has developed and commercialized micro abrasive (µAWJ), culminating A MicroMAX^® JetMachining^® Center technology for meso-micro machining. AWJ inherently possesses technological and manufacturing merits unmatched by most machine tools. With the commercialization of µAWJ technology, waterjet is now fully capable of multi-mode machining most materials from macro to micro scales (the 7M advantage). Novel accessories and software facilitate machining precision 2D and 3D parts with a wide range of part size and thickness. The versatile waterjet is particularly advantageous for machining difficult and delicate materials, such as alloys, hardened steel, composites, and laminates. One unique capability is machining composites and nanomaterials comprised of metals (reflective and conductive), non-metals (non-conductive), and anything in between. The 7M advantage of waterjet has been taking advantage by machining sample parts made of a variety of advanced materials that are difficult, or even impossible, to machine otherwise. Full article

This paper presents a new numerical approach for modelling the 3D printing process of fibre reinforced polymer composites by fused deposition modelling (FDM). The approach is based on the coupling between two particle methods, namely smoothed particle hydrodynamics (SPH) and discrete element method (DEM). The coupled SPH-DEM model has distinctive advantages in dealing with the free surface flow, large deformation of fibres, and/or fibre-fibre interaction that are involved in the FDM process. A numerical feasibility study is carried out to demonstrate its capability for both short and continuous fibre reinforced polymer composites, with promising results achieved for the rheological flow and fibre orientation and deformation. Full article

The melt-extrusion process is utilized in the pharmaceutical arena for the manufacturing of a variety of dosage forms and formulations, including solid dispersions. This technology is considered an efficient and continuous dosage form manufacturing method. However, there are potential challenges mainly because, during hot-melt extrusion, polymers are subject to mechanical and thermal degradation. Mechanical degradation may be induced by the shear effects imposed by the rotating screw. Thermal degradation results from high temperatures and includes random scission, scission from the ends of the polymer and unzipping of substitute groups. This paper endeavors to understand the impact of thermal and/or mechanical components of the melt-extrusion process on the stability of a pH sensitive polymer, namely Shellac. Correlation between the screw speeds and processing temperature profile was examined in the context of the overall degradation profile of the polymer. The results suggest that the processing stability of Shellac was reliant on optimization of screw speed (rpm) and process temperature. Full article

Bioabsorbable magnesium (Mg) alloys have several advantages in biomedical implant applications as they reduce certain risks associated with conventional permanent implants. However, limited information is available for WE43 Mg alloy specimens with comparable size to that of biomedical implants such as cardiovascular stents and orthopaedic wires. The present work examines the corrosion and biological properties of WE43 stent precursor tubes and wire specimens suited for orthopaedic implants. The corrosion-induced loss of mechanical integrity as well as the corrosion-induced changes in surface morphology of the specimens are elucidated and compared. Cell viability assays were performed with human umbilical vein endothelial cells (HUVECs). It was observed that Mg ions released from the WE43 alloy acted as a growth stimulator of HUVECs. Full article

Machining is one of the major manufacturing techniques where the material is removed to prepare the complete or sub-part. In general, this is also referred to as subtractive manufacturing. Due to solid-to-solid contact between the cutting tool and the work-piece, the machine dynamics get influenced by various operating parameters. This generates force and vibration, and thus noise. Over time the cutting tool reaches its end-of-life which increases the force to cut, and thus produces more vibration and noise. The noise parameter was considered in this work. A 32-element spherical microphone array acoustic camera system was used to record and analyze the sound that was emitted during the machining processes. The startup, idle, and load operating characteristics for various industrial machining equipment were monitored with the acoustic beam former microphone system. The industrial applications included a bench grinder, surface grinder, vertical band saw, lathe machine, and vertical milling machine. Analysis of the acoustic noise generated from these processes could demonstrate the similarities between the cyclical patterns of resonating sound. Full article

Nitrogen-vacancy (NV) in diamond possesses unique properties for the realization of novel quantum devices. Among the possibilities in the solid state, a NV defect center in diamond stands out for its robustness—its quantum state can be initialized, manipulated, and measured with high fidelity at room temperature. In this paper, we illustrated the formation kinetics of NV centers in diamond and their transformation from one charge state to another. The controlled scaling of diamond NV center-based quantum registers relies on the ability to position NV defect centers with high spatial resolution. Ion irradiation technique is widely used to control the spatial distribution of NV defect centers in diamond. This is addressed in terms of energetics and kinetics in this paper. We also highlighted important factors, such as ion struggling, ion channeling, and surface charging, etc. These factors should be considered while implanting energetic nitrogen ions on diamond. Based on observations of the microscopic structure after implantation, we further discussed post-annealing treatment to heal the damage produced during the ion irradiation process. This article shows that the ion implantation technique can be used more efficiently for controlled and efficient generation of NV color centers in diamond, which will open up new possibilities in the field of novel electronics and computational engineering, including the art of quantum cryptography, data science, and spintronics. Full article

Advanced high-strength steel (AHSS) is subject to a high deformation in geometry due to spring-back and high forces during forming. Therefore, dieless single-point incremental forming supported by induction heating was introduced. When a HCT980C steel part was studied, it was observed that the geometrical accuracy increased by forming using a 15 kW induction power, whereas a high deviation in profile geometry was observed by forming using a 5 kW induction power. The forming forces decreased by 66.63% compared with those resulting from forming at room temperature. At the same time, the HCT980C steel part cracked and failed to reach its designed depth when forming at room temperature. Regulating the tensile strength and hardness of the formed part and preventing their reduction was achieved by increasing the feed rate continuously as a function of the formed part’s growing depth. Moreover, the distribution of the induction heating temperature was reduced by introducing the new forming strategy. A cone wall angle of 70° was flexibly formed from a HCT980C steel sheet when the new strategy was applied. Full article

The modification of tribological properties of highly loaded components by selecting a suitable manufacturing process is state-of-the-art. Beyond the generation of microgeometrical structures, the present study investigates the potential of chemical alterations, i.e., metalworking fluid additives engaged in a grinding process to improve the chemical surface properties of machined gear synchronizations. These gearbox components ensure a uniform switching operation by harmonizing the number of revolutions between the power transmitting components by friction. A short running-in phase and a friction coefficient which is constant over the entire duration of use are required. The results show that the addition of polysulfide as well as zincdialkyldithiophosphate in the metalworking fluid could considerably reduce the friction coefficient fluctuations and the running-in phase of the generated synchronizations in later operation tests. The wear distances were lower although the machined parts revealed higher surface roughnesses as the reference workpieces, which indicates the formation of sorption or reaction layers of the additives with the metal surface. Full article

Direct Metal Deposition (DMD) is an additive manufacturing (AM) process capable of producing large components using a layer by layer deposition of molten powder. DMD is increasingly investigated due to its higher deposition rate and the possibility to produce large structural components specifically for the aerospace industry. During fabrication, a complex thermal history is experienced in different regions of the workpiece, depending on the process parameters and part geometry. The thermal history induces residual stress accumulation in the buildup, which is the main cause of distortions. In order to control the process and enhance the product quality, the understanding of the workpiece temperature is substantial. In this study, two methods to predict temperature evolution during the DMD process are introduced based on analytical and finite element methods. The objective is to compare these methods to experimental results and to provide more insights about their capabilities to predict accurately the temperature gradient, the cooling rate, and the melt pool geometry. A comparison of the computational time is also provided. Based on the results of the investigation, It appears that the analytical method provides an effective and accurate method to understand the influence of the process on the workpiece temperature. Full article

Prosumer (producing consumer)-based desktop additive manufacturing has been enabled by the recent radical reduction in 3-D printer capital costs created by the open-source release of the self-replicating rapid prototype (RepRap). To continue this success, there have been some efforts to improve reliability, which are either too expensive or lacked automation. A promising method to improve reliability is to use computer vision, although the success rates are still too low for widespread use. To overcome these challenges an open source low-cost reliable real-time optimal monitoring platform for 3-D printing from double cameras is presented here. This error detection system is implemented with low-cost web cameras and covers 360 degrees around the printed object from three different perspectives. The algorithm is developed in Python and run on a Raspberry Pi3 mini-computer to reduce costs. For 3-D printing monitoring in three different perspectives, the systems are tested with four different 3-D object geometries for normal operation and failure modes. This system is tested with two different techniques in the image pre-processing step: SIFT and RANSAC rescale and rectification, and non-rescale and rectification. The error calculations were determined from the horizontal and vertical magnitude methods of 3-D reconstruction images. The non-rescale and rectification technique successfully detects the normal printing and failure state for all models with 100% accuracy, which is better than the single camera set up only. The computation time of the non-rescale and rectification technique is two times faster than the SIFT and RANSAC rescale and rectification technique. Full article