International Journal of Advanced Manufacturing Technology最新文献

The constant development of new materials, such as ceramics with high wear resistance, makes it necessary to adapt machining processes by creating new methods or improving existing ones. Moreover, grinding is widely used as a finishing process in workpieces since it provides excellent surface roughness and dimensional tolerances. Due to the high volume of cutting fluid used in conventional lubrication (flood), associated with harmful effects such as contamination and intoxication, alternative methods have become highly necessary. The minimum quantity lubrication (MQL) technique reduces fluid use but has low cooling capacity, in addition to barely removing chips, making it essential to seek improvements to make it competitive. In this sense, adding water to the MQL can improve the cooling capacity at the cost of reducing lubrication. At the same time, applying a wheel cleaning jet (WCJ) of compressed air assists in chip removal. Thus, this work aims to analyze the results of external cylindrical grinding of alumina (Al₂O₃) using a synthetic diamond grinding wheel, comparing the techniques of conventional MQL, diluted MQL, and MQL + WCJ against the flood method. Surface roughness, roundness deviation, diametrical wheel wear, G ratio, grinding power, tangential cutting force, grinding cost analyses, and CO₂ pollution emission were conducted for this. The results show that adding water to MQL, associated with WCJ, significantly improved roughness, wear, and grinding power. Furthermore, the analysis of costs and pollution showed that using MQL significantly reduced costs and CO₂ emissions, proving the socio-environmental advantage of the MQL method against the flood method.

Abstract

Laser metal deposition (LMD) is of the directed energy deposition (DED) process which is widely used for producing large-scale, dense, and functional parts in the field of additive manufacturing (AM). This research work investigates the microstructure and mechanical properties of PH 13–8 Mo martensitic stainless-steel parts produced via LMD. The workshop trials were conducted using an LMD system collaborated with a robotic arm to deposit single-track thin walls and horizontal blocks. The microstructural characteristics of the additively manufactured parts were analyzed using an optical microscope. The mechanical properties were evaluated through hardness measurements and uniaxial tensile tests. The influence of energy density and powder deposition density on the characteristic geometry of straight walls was also investigated. The microstructural analysis showed that the microstructure consisted of columnar dendrites that grew epitaxially from the substrate, with primary austenite cells containing intercellular ferrite and martensite laths that were roughly parallel with the retained austenite. When the energy density increased from 43 to 86 J/mm² (a doubling of energy density), there was an increase in secondary dendritic arm spacing (SDAS) by approximately 250% in the first layer and approximately 90% in the top layer. The difference in SDAS change between the first and top layers can be attributed to the difference in cooling rates experienced by each layer during the additive manufacturing process. Increasing powder deposition density from 0.5 to 1 g/min results in a decrease in porosity from 3% to less than 1% and an increase in strength from 800 to over 1000 MPa. The hardness of the deposits was found to range from 300 to 400 HV. This variation in hardness can be attributed to differences in microstructure resulting from changes in cooling rates at different heights.

The escalating significance of 3D printing in various industries is underscored by its ability to rapidly and cost-effectively produce distinctive parts. Among the 3D printing methods, fused filament fabrication (FFF) has emerged as a highly productive and cost-effective approach. While extensive efforts have been made to enhance the qualities of FFF products, challenges persist in material availability and quality compared to traditional methods. This study provides a meticulous overview of the FFF process, delving into various 3D printing processes, polymers, and polymer composites. Despite documented efforts to augment mechanical, thermal, and electrical properties, material constraints remain a focal point. Our analysis extends to various PLA/biocomposites, shedding light on achieved improvements and potential applications. Looking forward, the future trend in FFF technology suggests a paradigm shift towards enhanced material diversity and performance. Anticipated applications span beyond traditional use cases, encompassing sustainable manufacturing, medical devices, and eco-friendly construction materials. This comprehensive review not only consolidates the current state of FFF and PLA-biocomposites but also anticipates future trends and potential applications. This research enhances the current knowledge of additive manufacturing and sets a standard for assessing developments in FFF technology by comparing them to previous works.

Graphical Abstract

The study explores the application of shot-peening (SP) on AISI 316L stainless steel to enhance mechanical properties. It focuses on optimizing SP parameters—coverage percentage (C) ranging from 100 to 4500% and shot velocity (P) between 1.5 and 6 bar while other SP factors were maintained constant—using response surface methodology (RSM) entails creating a mathematical model to analyze data accurately. This model explores interactions among initial configurations to optimize mechanical properties and enhance the performance of the current steel after the SP surface treatment. These properties evaluated include cumulative compressive residual stress (CCRS), cumulative full-width at half-maximum (CFWHM) newfangled factors for researchers to analyze, austenite transformation to martensite, micro-hardness, and surface roughness. Through the RSM model, increasing P leads to an increase in all response values in each one, except for microhardness, which registers a minor decrease from 1.5 to 6 bar. Elevating C promotes responses, excluding roughness, decreasing until 2300% and reaching its minimum. At 4500% C, roughness peaks, exceeding the initial amount at 100% C. In the optimization section, it seeks a passable value for each parameter. Desired responses involve maximizing CCRS, CFWHM, and micro-hardness while minimizing martensite and roughness. For interactions in all responses, at P = 6 bar and C = 1860%, values for each response were CCRS = 218 (MPa.mm), CFWHM = 0.6871 (°.mm), micro-hardness = 394 (HV), martensite conversion = 48 (%), and roughness = 5.45 (µm). Response reassessment in the real tests by comparison RSM model in optimal points showed a minimum error of 4.05 for roughness and a maximum error of 12.09 for CCRS. Other responses contained errors between this spectrum.

Additive manufacturing (AM) has shown advantages to fabricate complex components in an efficient way. However, it has some limitations related to imperfections on the as-built parts that may limit its mechanical behavior and performance. The aim of this paper is to investigate the effect of laser shock peening (LSP) as a post-processing technique of components produced by AM. Porosity, microstructure, residual stresses, and fatigue life of Inconel 718 samples manufactured by laser powder bed fusion (LPBF) and then treated by LSP have been evaluated. For the laser shock peening (LSP) treatment, a Nd:YAG pulsed laser operating at 10 Hz with 1064 nm of wavelength was used; pulse density was 2500 pulses/cm². The LSP setup was the waterjet arrangement without protective coating. Residual stress distribution as a function of depth was determined by the hole-drilling method. Fatigue specimens were LSP treated on both sides and then cyclic loading was applied with R = 0.1. Residual stress profiles of as-built specimens showed tensile residual stresses while specimens with LSP exhibited compressive residual stresses. Fatigue life in specimens with stress relief heat treatment plus LSP showed an increase of 18–22% with respect to that of as-built specimens. Porosity levels were lower than 1% in the tested specimens, while surface microhardness increased due to LSP. It is shown that LSP is a viable alternative to improve the performance of IN718 components processed with AM.

Graphical Abstract

In the digital measuring environment, to solve the problem of sampling point planning on the aero-engine blade profile, two requirements should be satisfied: adapting geometry features and keeping the sampling point spacing. Therefore, this paper proposes an adaptive sampling method, which can flexibly increase or decrease the sampling points according to the curvature. Firstly, according to the geometric characteristics of blade profile, an adaptive sampling method based on the equal moment theory is established. Secondly, a parameterized model based on non-uniform rational B-spline (NURBS) is used to represent the geometry of the blade profile, and the Hausdorff distance is used to evaluate the error of the fitting curve. Finally, two cases verify the effectiveness and accuracy of the proposed method. In the simulation, the relationship between the adaptability and the error of the proposed method is analyzed by taking the Sine function as an example. It is obtained by numerical calculations that the error reached the minimum when the adaptive degree r is 0.75. In the actual blade measurement experiment, compared with other methods, the deviation between the reconstructed blade cross-section curve by the proposed method and the theoretical curve is minimum.

A new process technique called rapid heat cycle molding (RHCM) has been developed using a carbon nanotube (CNT) web film as a heat source for the mold. Although various heating technologies have been applied as RHCM techniques, low energy efficiency has caused productivity to decrease. To improve this issue, the RHCM process was implemented using a CNT web film for more efficient heating. A multilayer structure module was designed to apply the CNT web film to a full-size injection mold. The RHCM process was implemented by designing stable heat transfer and electrical insulation through a multilayer structure module. When power was applied, the temperature rose quickly, with the highest heating rate reaching 41 °C/s at 40 kW, and the highest temperature achieved at about 300 °C. The temperature uniformity and stability were tested on 6 points of the cavity surface, and an average of 97% temperature uniformity and stability was observed during heating. In production testing of the Center Fascia (CTR.FASCIA), which is an internal automobile part made of polycarbonate/polybutylene terephthalate composites, an RHCM process was conducted. The width and depth of weld lines in the molded products were eliminated, and a 26% improvement in glossiness and surface quality was observed compared to the conventional injection molding process (CIM). CNT web film is a versatile and flexible material that can be applied in various forms, and it has been confirmed that by utilizing this material to create a multilayer structure module, the RHCM process can be performed reliably.

In the grinding process of crankshafts, the grinding parameters were improperly selected, which easily caused the high temperature in the grinding zone and led to burns on the crankshaft journal surface. To address this issue, referencing previous studies, the suitability of the Gaussian heat source model was verified by comparing it with three different heat source models. The Gaussian heat source model was applied to predict the temperature on the surface of the crankshaft connecting rod journal. Transient thermal analysis and investigation of material phase transformation were employed to explore the mechanism of grinding burns. The interaction effects among grinding parameters were analyzed using the Box-Behnken design, and a multiple linear regression equation was established for response surface optimization. The results demonstrated that applying the Gaussian heat source model and response surface optimization yielded the optimal solution, with a maximum deviation of 1.37% between the simulation and optimization results. By selecting a grinding depth (a_p) of 0.40 mm, wheel speed (v_s) of 40.00 m/s, and feed rate (v_x) of 0.036 mm/s as the processing parameters, the temperature in the grinding zone was reduced to 659.37 °C, effectively mitigating grinding burns.

A metallic foam specimen was plastically joined with a resin (polymethyl methacrylate, PMMA) sheet by applying friction stir incremental forming (FSIF) process. In FSIF process, a rotating flat-ended (no probe) rod tool was pushed vertically and fed horizontally against the resin sheet which was placed on the foam. The tool operation heated frictionally the resin and deformed incrementally to the resin, while the tool operation did not deform plastically to the cellular matrix of the foam. Due to the plastic flow of the heated resin, the bottom of the resin was interlocked mechanically to the pores near the top surface of the foam. In this study, the relationship between the pore morphology (form and size) and the joining characteristics (joinability, flow thickness of the resin, and joining strength) was investigated using commercial open-cell nickel and closed-cell aluminum foams. According to the experimental investigations, the foam with small size and low depression angle of the surface pore showed better results in relation with the joining strength and the (flow thickness of the resin)/(depth of the surface pore).

Abstract

The laser separation distance (distance between the two lasers in welding direction) in double-sided laser beam oscillation filler welding is difficult to precisely control. To evaluate the effect of laser separation distance on the mechanical properties of T joints, 2219 aluminum alloy double-sided laser beam oscillation filler welding experiments with different laser separation distances were conducted in this work. With laser separation, the symmetry of fusion zone was weakened. The keyhole stability at latter welding side was weakened. The number of pores in the T joint increased. The laser separation distance promoted the formation of porosity at latter welding side and the formation of porosity in the stringer. Most of the cracks in the tensile tests at the weld foot propagated in the partially melted zone. Porosity has no significant influence on the tensile strength of T joints. When laser separation distance was 3 mm, the mechanical performance of T joint was the best. The hoop tensile strength was 370.0 MPa. The T-pull tensile strength was 309.5 MPa. Based on the results of tensile strength testing, the mechanical performance of T joints welded by double-sided laser beam oscillation filler welding did not deteriorate with the laser separation distance less than or equal to 3 mm, which showed a good tolerance of laser separation distance for the welding process.