Advances in Industrial and Manufacturing Engineering最新文献

This paper investigates the possibility of using empirical tool life models to predict tool life in a side milling application in a medium carbon steel, C 45E. To do this, an extensive dataset containing 46 data points with different machining parameters are produced. Four different empirical models: Taylor’s equation, Colding’s equation and Extended Taylor both using depth of cut and feed as well as an Extended Taylor using equivalent chip thickness has been considered. It is found that Colding’s equation is best suited to predict the tool life for this application. Furthermore, this paper suggests a novel method to fit the experimental data to the empirical models. Based on the results from previously published papers it is shown that the proposed method performs equally or better to determine the model constants.

Elastomers play a significant role across different fields including healthcare. They have similar mechanical properties to some of the soft tissues of the human body, which makes them useful in applications such as implants and prosthetics. However, forming elastomers for tailored-fit medical devices using 3D printing is still not yet widely utilized because of the current problems seen as innate to the elastomer properties, and the principles of 3D printing techniques. With a focus on silicone and polyurethane, this review details the state-of-the-art 3D printing techniques that are being modified over the years to allow its printability for medical applications. The paper also discusses the manufacturing challenges faced by the researchers in printing elastomers, and how these challenges are currently being addressed. This review paper shows further research direction and hopes to initiate further development of these solutions. This will allow the 3D printing of elastomers to gain widespread use in patient-specific medical devices and components with optimized functionality in the near future.

Forward rod extrusion experiments with high extrusions strains show a decrease of void area during forming. Most of the established damage modelling approaches have been developed without that knowledge and do not adequately cover the effect of void closure. Furthermore, many so called coupled models focus on the effect of ductile damage on the plastic flow of the material which results in more complex and numerically expensive models. But the effect of voids on plastic flow is insignificant for many cold forging applications, as shown in recent experiments. Thus, an uncoupled model is proposed that covers the effects of void nucleation, growth and closure. The proposed model is calibrated using void area fractions measured in forward rod extrusion experiments. A validation for various load paths shows good accordance with experimental data for void closure conditions under low triaxiality as well as for void evolution under higher triaxialities.

Manganese sulphide inclusions are commonly found in steels and known to facilitate the formation of deformation-induced damage sites in the form of voids during cold forming. These damage sites either exist as cracks, splitting the inclusion in two parts, or as delamination, separating the inclusion from the surrounding steel matrix. Both negatively influence the longevity of components, especially under cyclic loading. The analysis of damage is inherently scale-bridging, ranging from deteriorated global mechanical properties of the finished part, over the damage behaviour of individual inclusions, to the local description of individual voids. In this work, we set out to devise an analysis approach gathering information on all these scales. To this end, we conducted in-situ tensile tests while acquiring high resolution SEM panoramic images and analysed them with two neural networks, trained for this work, to detect damage sites with respect to the inclusions at which they nucleated. We find that the main damage mechanism during tensile deformation parallel to the length of inclusions is cracking and that damage evolution is equally influenced by void nucleation and void growth in the observed range of deformation. By focussing on the damaging behaviour of different inclusions, we show that the position of inclusions in the microstructure influences the resulting damage evolution and that the vicinity of pearlite bands leads to decreased damage formation.

Steels with high carbon content can hardly or not at all be welded, but are of great interest for cladding applications due to their high hardness. In this study, the influence of process parameters on weld seam geometry and process stability is investigated when welding AISI 52100 bearing steel using the laser hot-wire cladding process. Process stability is evaluated using actual and set values for the wire feed rate and current parameters to determine a process window for a stable welding process. Weld seams are measured and analyzed in terms of width, height, contact angle, and shape. The effect of the process parameters on the weld seam geometry is investigated and appropriate mathematical functions to describe the geometry are determined. Process parameter sets in the range of 1-2 m/min wire feed rate and 45-75 A hot wire current were investigated. Unstable parameter sets occur clustered at high wire feed rate of 2 m/min for all hot wire currents. In addition, the process is unstable at high hot wire current of 75 A and low wire feed speed of 1 m/min. The remaining parameter sets resulted in a stable process. The investigated functions parabolic, cosinusoidal and circular arc for the mathematical description of the weld seam geometry, no clearly significant result could be determined. Only a trend towards the circular arc function and the parabolic function is apparent.

This paper presents a parallel zigzag (raster) tool-path generation method for Additive Manufacturing (AM). Based on the analysis of some ordinary serial algorithms, it was observed that some compute-intensive operations could be parallelized by using a Graphics Processing Unit (GPU) architecture. However, to achieve this, many challenges were faced and solved by designing a method to work concurrently with individual contour segments on multiple layers while keeping the data organized. The method’s ability to solve the zigzag generation problem was verified, and its performance was measured by running an exhaustive search for optimal raster angles to reduce manufacturing time. The results showed that the method was effective and generated relevant computational gain, being up to 9 times faster than its serial counterpart. In the tool-path optimization, the simulations found configurations yielding an average length of raster lines up to 38% longer, which, in turn, can reduce manufacturing time.

Additive Manufacturing (AM) is one of the key technologies of Industry 4.0, offering unique advantages and capabilities. The interest in AM has been steadily increasing, leading to its rapid recent growth and improvement in all its aspects. However, its wider adoption is hindered by various barriers, the most important of which are the relatively high initial investment cost, part quality issues, limited material choices, and lack of expertise. The research community, AM machine developers, and larger enterprises are continuously contributing to the improvement of the first three factors. Nonetheless, the same cannot be stated for the barrier of limited expertise, leading the industrial sector to a perpetual lack of knowledge and, therefore, reluctance for a potential AM uptake. This study is addressing the need of the industrial sector for structured and organized expertise training for the fruitful exploitation of AM, paving the road for its wider application. The guidelines for an industrial-oriented AM training curriculum are set through the development of an AM training framework. The different AM thematic areas are classified into educational modules, which are separately analyzed, considering the participants’ active role and hands-on practice. The proposed step-by-step approach builds up from introductory to more advanced concepts, ensuring flexibility and simultaneously encompassing the needs of all industrial stakeholders (engineers, designers, managers, operators). Additionally, strategies corroborating the accessibility of the proposed framework are discussed, as well as dissemination policies and tools to facilitate its industrial endorsement.

The industrial progress made throughout these years has led to great results in terms of producing fast and with good quality. However, the impacts related to that production, whether these are environmental, economic, or social have been, at times, neglected. The manufacturing sector, as one of the most polluting sector, felt the urge to adapt to this industrial progress and find ways to produce with improved sustainability goals without compromising the quality of the final product and the production time. Industry easily understood the benefits of this greener approach, and, with this, new sustainable technologies started to emerge. Additive Manufacturing (AM) is one of those technologies that provide alternative sustainable paths to traditional manufacturing. In order to generalize the benefits of AM production in terms of sustainability, when compared to traditional processes, further investigations must be conducted. In this sense, the proposed work has the intention of finding the environmental impacts associated with a particular AM technique for the fabrication of metal parts, Wire Arc Additive Manufacturing (WAAM). A practical work based on the production of three different complexity metal parts considering an additive (WAAM) and a subtractive (Computer Numerical Control (CNC) Milling) manufacturing process is developed. To quantify the environmental impacts of both processes, the author resorts to the Life Cycle Assessment (LCA) methodology. The assessment is conducted in the SimaPro 9.2 software, accordingly to ISO 14044:2006 standard. The results allow a comparison between both types of manufacturing and enable the suggestion of measures to decrease the environmental footprint of WAAM. It was found that WAAM approach leads to a material saving ranging between 40% and 70% and an environmental impact reduction in the range of 12%–47%, compared to the subtractive approach for fabricating the 3 geometries considered in this study. The conclusions obtained are specific to this particular application and, once more, it is acknowledged that in order to reach a global understanding relative to this technology's environmental implications, extra research still needs to be made.

The cost-effectiveness and the environmental impact of Additive Manufacturing (AM) are nowadays two of the hottest process-related industrial and research topics. Energy efficiency is a strong claim, and so is the demand for durable and functional 3D-printed workpieces. These contradictory aspects usually require flexibility and compromises. Especially for Material Extrusion (MEX) 3D printing, the plurality of the control parameters makes such optimizations complicated. This research explores the effect of seven generic and machine-independent control factors (e.g., Raster Deposition Angle; Orientation Angle; Layer Thickness; Infill Density; Nozzle Temperature; Bed Temperature, and Printing Speed) on energy consumption of Polylactic Acid over the compressive response of MEX 3D printed specimens. To make it possible, a three-level L27 orthogonal array was compiled. Each experimental run included five specimen replicas (after the ASTM D695-02a standard) summing up 135 experiments. The fabrication time and the energy consumption were determined by the stopwatch method, whereas the compressive strength, elasticity modulus, and toughness were derived with compressive tests. The Taguchi analysis ranked the impact of each control parameter on each response metric. The printing speed and the layer thickness were the most influential control parameters on energy consumption. Furthermore, the infill density and the orientation angle were found as the most dominant factors in the compressive strength. Finally, Quadratic Regression Model (QRM) equations for each response metric over the seven control parameters were compiled and validated. Hereto, the best settlement between energy efficiency and mechanical strength is now possible, an option with great technological and industrial merit.

Lightweight constructions made of different materials are becoming increasingly important and joining of metal-plastic hybrids is a major challenge in this context. This paper investigates experimentally the electromagnetic joining of tubes made of aluminum alloy 6082 and thermoplastic polycarbonate. Therefore, electromagnetic joining tests, combined with destructive push-out tests and non-destructive computer tomography scans were conducted. The investigations showed a fundamental dependence of the joint strength on the diameter ratio of the inner joining partner. By increasing the ratio of inner to outer diameter, the transferable push-out force was increased by factor fifteen. Furthermore, for lower ratios, macroscopic cracks were detected that limited the transferable forces.