Fractal Analysis of Cutting Force and Acoustic Emission Signals During CFRP Machining

AbstractCutting forces and acoustic emissions signals while machining Fiber Reinforced Plastics (FRP) depends strongly on the tool wear. Fractal analysis can be adapted to those signals to characterize their variations. This tool wear monitoring technique is presented herein for the carbon FRP (CFRP) orbital drilling. Fractal parameters, characterizing the signal complexity and ruggedness, are very efficient for machining quality estimation and to follow the tool wear evolution

Fractal analysis application outlook for improving process monitoring and machine maintenance in manufacturing 4.0

ABSTRACT: Industry 4.0 has been advertised for a decade as the next disruptive evolution for production. It relies on automation growth and particularly on data exchange using numerous sensors in order to develop faster production with tight monitoring. The huge amount of data generated by clouds of sensors during production is often used to feed machine learning systems in order to detect faults, monitor and find possible ways for improvement. However, the artificial intelligence within machine learning requires finding and selecting key features, such as average and root mean square. While current machine learning has already proven its use in diverse applications, its efficiency could be further improved by generating better characteristics such as fractal parameters. In this paper, fractal analysis concept is presented and its current and future applications in machining are discussed. This sensitive and robust technique is already extracting high performance key features that could fill in monitoring and prediction systems. On top of improving features selection and, thus, improving the overall performance of monitoring and predictive systems in machining, this could lead to a more rapid artificial intelligence implementation into manufacturing

Machining of titanium metal matrix composites : progress overview

ABSTRACT: The TiC particles in titanium metal matrix composites (TiMMCs) make them difficult to machine. As a specific MMC, it is legitimate to wonder if the cutting mechanisms of TiMMCs are the same as or similar to those of MMCs. For this purpose, the tool wear mechanisms for turning, milling, and grinding are reviewed in this paper and compared with those for other MMCs. In addition, the chip formation and morphology, the material removal mechanism and surface quality are discussed for the different machining processes and examined thoroughly. Comparisons of the machining mechanisms between the TiMMCs and MMCs indicate that the findings for other MMCs should not be taken for granted for TiMMCs for the machining processes reviewed. The increase in cutting speed leads to a decrease in roughness value during grinding and an increase of the tool life during turning. Unconventional machining such as laser-assisted turning is effective to increase tool life. Under certain conditions, a “wear shield” was observed during the early stages of tool wear during turning, thereby increasing tool life considerably. The studies carried out on milling showed that the cutting parameters affecting surface roughness and tool wear are dependent on the tool material. The high temperatures and high shears that occur during machining lead to microstructural changes in the workpiece during grinding, and in the chips during turning. The adiabatic shear band (ASB) of the chips is the seat of the sub-grains’ formation. Finally, the cutting speed and lubrication influenced dust emission during turning but more studies are needed to validate this finding. For the milling or grinding, there are major areas to be considered for thoroughly understanding the machining behavior of TiMMCs (tool wear mechanisms, chip formation, dust emission, etc.)

Study of the effects of initial cutting conditions and transition period on ultimate tool life when machining inconel 718

ABSTRACT: Rapid tool wear and limited tool life are major problems when machining Inconel 718, which still need further attention. Amongst the reported strategies, limited studies have been reported on optimizing initial cutting conditions by means of tool life improvement. Therefore, in this work, the tool wear progress and tool life were investigated by varying the initial conditions in the transition period, which was set at four seconds. The transition point was discovered by previous works by the authors. After the transition point, similar cutting conditions were used as the reference condition. The tool wear morphology and size were recorded and analyzed in each condition. It was revealed that applying a lower cutting speed and feed rate in the transition period led to improved tool life as compared to the reference condition. In other words, the use of optimum levels of cutting parameters in the transition period of the cutting process may enhance tool life at higher cutting time. For instance, initial feed rate (0.15 mm/rev) and cutting speed (25 m/min) led to the improvement in the ultimate tool life by about 67% and 50%, respectively. Besides, applying the lower initial cutting speed, i.e., 25 m/min, increased the tool life by about 50% when the insert reached the maximum flank wear (vBmax) of 300 µm in comparison with those at higher initial cutting speeds. This phenomenon may lead to better insight into the effect of the influence of the initial cutting conditions in the transition period on tool life when machining hard-to-cut materials. Moreover, the built-up edge (BUE) was exhibited as the primary wear mode in all cutting conditions

Experimental characterization of tool wear morphology and cutting force profile in dry and wet turning of titanium metal matrix composites (Ti-MMCs)

ABSTRACT: Metal-matrix composites (MMCs) are made of non-metallic reinforcements in metal matrixes, which have excellent hardness, corrosion, and wear resistance. They are also lightweight and may pose a higher strength-to-weight ratio as compared to commercial titanium alloys. One of the MMCs with remarkable mechanical properties are titanium metal matrix composites (Ti-MMCs), which are considered a replacement for super-alloys in many industrial products and industries. Limited machining and machinability studies of Ti-MMCs were reported under different cutting and lubrication conditions. Tool wear morphology and life are among the main machinability attributes with limited attention. Therefore, this study presents the effects of cutting and lubrication conditions on wear morphology in carbide inserts when turning Ti-MMCs. To that end, maximum flank wear (VB) and cutting forces were recorded, and the wear morphologies within the initial period of the cut, as well as the worn condition, were studied under dry and wet conditions. Experimental results denoted that despite the lubrication mode used, abrasion, diffusion, and adhesion mechanisms were the main wear modes observed. Moreover, built-up layer (BUL) and built-up edge (BUE) were the main phenomena observed that increase the tendency of adhesion at higher cutting times

Dry and semi-dry turning of titanium metal matrix composites (Ti-MMCs)

ABSTRACT: Metal matrix composites (MMCs) are composed of non-metallic reinforcements (i.e., ceramic) in metal matrices which feature high toughness, wear and fatigue resistant and relatively light-weight. One of the metallic composites with remarkable mechanical properties is titanium metal matrix composite (Ti-MMC) that is considered as an alternative to nickel-based alloys. Despite excellent mechanical and physical features of Ti-MMC, due to high price and presence of hard and abrasive ceramic particles in metal matrices, machining, and machinability of Ti-MMCs is a complex subject. Knowing that very limited studies are available on machining Ti-MMCs under various flow rates and lubrication modes, adequate knowledge about the effects of cutting parameters and lubrication modes on machining attributes is a critical issue. Therefore, this study intends to present the turning of Ti-MMC under dry and semi-dry modes at various levels of flow rates. Effects of cutting parameters on several machining attributes including cutting forces, surface roughness, and particle emission will be presented in the course of this study

Par une discipline rigoreuse et illustrés: l'inspection dans la capitale de l'empire Brésilien

O objetivo deste estudo é analisar os procedimentos manejados na fiscalização de professores primários, por meio do estudo a respeito do serviço de inspeção da instrução na Corte Imperial, a partir de sua institucionalização com base no Regulamento da Instrução Primária e Secundária da Corte em 1854. Na pesquisa procurou-se discutir como a visibilidade dada à escola e aos seus atores, via inspeção, permitiram inseri-los em um esquema disciplinar, cujos efeitos encontram-se articulados e justificados em nome de um projeto de ordenação e civilização da capital do Império brasileiro

Surface profile topography of trimmed and drilled carbon/epoxy composite

ABSTRACT: The surface finish of Fiber Reinforced Plastic (FRP) laminate is challenging to characterize, due to the heterogeneous structure of the composite. Profile roughness parameters are highly impacted by the different layer properties, and their distributions are relatively spread out. In this paper, the surface topography of a 24-ply quasi-isotropic Carbon FRP (CFRP) is observed through primary profiles and the roughness parameter Ra in the transverse direction on trimmed and drilled CFRP surfaces. The surface characterization using the Ra parameter is found inadequate in providing useful information as to the machined surface quality

Surface profile topography of trimmed and drilled carbon/epoxy composite

ABSTRACT: The surface finish of Fiber Reinforced Plastic (FRP) laminate is challenging to characterize, due to the heterogeneous structure of the composite. Profile roughness parameters are highly impacted by the different layer properties, and their distributions are relatively spread out. In this paper, the surface topography of a 24-ply quasi-isotropic Carbon FRP (CFRP) is observed through primary profiles and the roughness parameter Ra in the transverse direction on trimmed and drilled CFRP surfaces. The surface characterization using the Ra parameter is found inadequate in providing useful information as to the machined surface quality