Pub Date : 2024-10-01DOI: 10.1016/j.mfglet.2024.09.040
Yitian Chi , Xiaochun Li
High-performance wrought aluminium alloys are widely used in automobiles and aerospace industries owing to their high-volume precipitates after heat treatment. Investment casting as one of the precision manufacturing methods provides great potential to achieve excellent surface finishes and complex geometry for aluminium alloy components. However, these high-performance aluminium alloys are almost impossible to be investment cast due to their hot cracking susceptibility and severe shrinkage during solidification. In this study, we introduce nanotechnology to improve the processability of high-performance wrought aluminium alloys in investment casting by adding a small volume fraction of nanoparticles into the aluminium alloys. This work showed the unprecedented success of nanotechnology-enabled investment casting of high-strength wrought aluminium alloys (AA6061, AA2024, and AA7075) for excellent mechanical properties.
{"title":"Nanotechnology-enabled rapid investment casting of high-performance wrought aluminum alloys","authors":"Yitian Chi , Xiaochun Li","doi":"10.1016/j.mfglet.2024.09.040","DOIUrl":"10.1016/j.mfglet.2024.09.040","url":null,"abstract":"<div><div>High-performance wrought aluminium alloys are widely used in automobiles and aerospace industries owing to their high-volume precipitates after heat treatment. Investment casting as one of the precision manufacturing methods provides great potential to achieve excellent surface finishes and complex geometry for aluminium alloy components. However, these high-performance aluminium alloys are almost impossible to be investment cast due to their hot cracking susceptibility and severe shrinkage during solidification. In this study, we introduce nanotechnology to improve the processability of high-performance wrought aluminium alloys in investment casting by adding a small volume fraction of nanoparticles into the aluminium alloys. This work showed the unprecedented success of nanotechnology-enabled investment casting of high-strength wrought aluminium alloys (AA6061, AA2024, and AA7075) for excellent mechanical properties.</div></div>","PeriodicalId":38186,"journal":{"name":"Manufacturing Letters","volume":"41 ","pages":"Pages 339-343"},"PeriodicalIF":1.9,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142434243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01DOI: 10.1016/j.mfglet.2024.09.002
{"title":"History of NAMRI and NAMRC","authors":"","doi":"10.1016/j.mfglet.2024.09.002","DOIUrl":"10.1016/j.mfglet.2024.09.002","url":null,"abstract":"","PeriodicalId":38186,"journal":{"name":"Manufacturing Letters","volume":"41 ","pages":"Pages 3-5"},"PeriodicalIF":1.9,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142434335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01DOI: 10.1016/j.mfglet.2024.09.051
Jake Dvorak , Dustin Gilmer , Ross Zameroski , Tony Schmitz
This paper describes a manufacturing approach for carbon-bonded carbon fiber where cyanoacrylate and wax infiltration are used to improve the handling and machinability of preforms. Structured light optical coordinate metrology is used to acquire a stock model for computer-aided manufacturing and work coordinate system definition for machining. Non-infiltrated (neat) and infiltrated samples are machined using the same part program to compare results. Geometric attributes are measured with a touch trigger probe coordinate measuring machine and surface characteristics are measured with an optical 3D measuring system. Experimental results show superior geometric accuracy and surface roughness for the infiltrated samples over the neat sample.
本文介绍了一种碳键合碳纤维的制造方法，该方法使用氰基丙烯酸酯和蜡浸润来改善预型件的处理和可加工性。结构光光学坐标测量法用于获取用于计算机辅助制造和加工工件坐标系定义的毛坯模型。使用相同的零件程序对未浸润（纯净）和浸润样品进行加工，以比较结果。几何属性用触发式测头坐标测量机测量，表面特征用光学 3D 测量系统测量。实验结果表明，浸润样品的几何精度和表面粗糙度均优于未浸润样品。
{"title":"Milling infiltrated carbon-bonded carbon fiber: Geometric attributes, surface characteristics, and feasibility","authors":"Jake Dvorak , Dustin Gilmer , Ross Zameroski , Tony Schmitz","doi":"10.1016/j.mfglet.2024.09.051","DOIUrl":"10.1016/j.mfglet.2024.09.051","url":null,"abstract":"<div><div>This paper describes a manufacturing approach for carbon-bonded carbon fiber where cyanoacrylate and wax infiltration are used to improve the handling and machinability of preforms. Structured light optical coordinate metrology is used to acquire a stock model for computer-aided manufacturing and work coordinate system definition for machining. Non-infiltrated (neat) and infiltrated samples are machined using the same part program to compare results. Geometric attributes are measured with a touch trigger probe coordinate measuring machine and surface characteristics are measured with an optical 3D measuring system. Experimental results show superior geometric accuracy and surface roughness for the infiltrated samples over the neat sample.</div></div>","PeriodicalId":38186,"journal":{"name":"Manufacturing Letters","volume":"41 ","pages":"Pages 429-434"},"PeriodicalIF":1.9,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142434254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01DOI: 10.1016/j.mfglet.2024.09.032
Wayne Cai, Matthew Bondy, Blair Carlson, Mark Baylis
Thermal-induced distortion prediction of thin shell structures is a challenging task. It often involves highly nonlinear buckling behaviour, where the critical buckling temperature and post-buckling deformations are very sensitive not only to structural stiffness and boundary conditions but also minute geometric imperfections (a.k.a., “surface quality”) of the incoming parts. In the present work, novel Computer Aided Engineering (CAE) methods were developed to predict the thermal-induced distortion of automotive Body-in-White (BIW) panels during paint shop oven-baking processes. The CAE methodology consist of a set of three Finite Element Analysis (FEA) procedures, i.e., thermal-buckling mode analysis, thermo-structural analysis, and imperfection analysis. Two vehicle level case studies showed that simulations successfully predicted the thermal-induced distortion for panels such as the Body Side Outer (BSO) header. It was concluded that the distortion depends primarily on the temperature difference between the BSO and the rest of the BIW during the oven-baking process, rather than the temperatures themselves. Body panel forming quality (e.g., residual stresses and thickness thinning) and assembly dimensional quality were also found to impact the distortions.
{"title":"Prediction of automotive body-in-white distortion in paint baking process","authors":"Wayne Cai, Matthew Bondy, Blair Carlson, Mark Baylis","doi":"10.1016/j.mfglet.2024.09.032","DOIUrl":"10.1016/j.mfglet.2024.09.032","url":null,"abstract":"<div><div>Thermal-induced distortion prediction of thin shell structures is a challenging task. It often involves highly nonlinear buckling behaviour, where the critical buckling temperature and post-buckling deformations are very sensitive not only to structural stiffness and boundary conditions but also minute geometric imperfections (a.k.a., “surface quality”) of the incoming parts. In the present work, novel Computer Aided Engineering (CAE) methods were developed to predict the thermal-induced distortion of automotive Body-in-White (BIW) panels during paint shop oven-baking processes. The CAE methodology consist of a set of three Finite Element Analysis (FEA) procedures, i.e., thermal-buckling mode analysis, thermo-structural analysis, and imperfection analysis. Two vehicle level case studies showed that simulations successfully predicted the thermal-induced distortion for panels such as the Body Side Outer (BSO) header. It was concluded that the distortion depends primarily on the temperature difference between the BSO and the rest of the BIW during the oven-baking process, rather than the temperatures themselves. Body panel forming quality (e.g., residual stresses and thickness thinning) and assembly dimensional quality were also found to impact the distortions.</div></div>","PeriodicalId":38186,"journal":{"name":"Manufacturing Letters","volume":"41 ","pages":"Pages 270-280"},"PeriodicalIF":1.9,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142434280","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01DOI: 10.1016/j.mfglet.2024.09.034
Guangyan Ge , Yukun Xiao , Jun Lv , Zhengchun Du
Thin-walled parts have significant application value in the aerospace industry due to their high strength-to-weight ratio. However, their low rigidity makes them susceptible to cutting force-induced error, which may seriously affect their machining accuracy. Error compensation is an effective method for addressing this issue. However, the commonly used mirror compensation method can cause residual errors due to the coupling effect of the tool-workpiece deformation. The influence mechanism of this coupling effect on error compensation is analyzed through an iterative compensation method. This method efficiently reduces residual errors. However, its computation efficiency is insufficient to meet the requirements of real-time compensation. Therefore, a non-iterative compensation method is proposed to directly calculate the compensation values considering the coupling effect of the tool-workpiece deformation. Through the approximate invariance of the overall cutting coefficient matrix and the pre-given system parameter, the proposed method avoids the repeated calculation of cutting forces and improves the computation efficiency. Experiment results of milling thin-walled blades show that after compensation using the proposed method, the machining accuracy of the thin-walled blade has seen a further increase of 18.1% in comparison to the mirror compensation method. Moreover, the proposed method achieves comparable compensation accuracy to the iterative method with a 66% reduction in computation time. The proposed method has significant potential for real-time compensation in the machining of complex 5-axis thin-walled parts.
{"title":"A non-iterative compensation method for machining errors of thin-walled parts considering coupling effect of tool-workpiece deformation","authors":"Guangyan Ge , Yukun Xiao , Jun Lv , Zhengchun Du","doi":"10.1016/j.mfglet.2024.09.034","DOIUrl":"10.1016/j.mfglet.2024.09.034","url":null,"abstract":"<div><div>Thin-walled parts have significant application value in the aerospace industry due to their high strength-to-weight ratio. However, their low rigidity makes them susceptible to cutting force-induced error, which may seriously affect their machining accuracy. Error compensation is an effective method for addressing this issue. However, the commonly used mirror compensation method can cause residual errors due to the coupling effect of the tool-workpiece deformation. The influence mechanism of this coupling effect on error compensation is analyzed through an iterative compensation method. This method efficiently reduces residual errors. However, its computation efficiency is insufficient to meet the requirements of real-time compensation. Therefore, a non-iterative compensation method is proposed to directly calculate the compensation values considering the coupling effect of the tool-workpiece deformation. Through the approximate invariance of the overall cutting coefficient matrix and the pre-given system parameter, the proposed method avoids the repeated calculation of cutting forces and improves the computation efficiency. Experiment results of milling thin-walled blades show that after compensation using the proposed method, the machining accuracy of the thin-walled blade has seen a further increase of 18.1% in comparison to the mirror compensation method. Moreover, the proposed method achieves comparable compensation accuracy to the iterative method with a 66% reduction in computation time. The proposed method has significant potential for real-time compensation in the machining of complex 5-axis thin-walled parts.</div></div>","PeriodicalId":38186,"journal":{"name":"Manufacturing Letters","volume":"41 ","pages":"Pages 287-295"},"PeriodicalIF":1.9,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142434282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01DOI: 10.1016/j.mfglet.2024.09.093
Tianqi Zheng , Changyu Ma , Alexander Killips , Bingbing Li , Xiaochun Li
Wrought aluminum alloy AA6061 is widely used in automotive, aerospace, and other industries due to its good properties, including high strength, excellent corrosion resistance, and good weldability. However, when using Laser Powder Bed Fusion (LPBF) for AA6061, hot cracking becomes a serious problem. In this work, AA6061 powder with internally dispersed nanoparticles has been adopted in a LPBF process. Through optimization of printing parameters, components with minimal porosity (less than 0.5 %) have been successfully produced without cracks. Additionally, by employing a chessboard printing strategy to create finely detailed cellular and grain structures, we have achieved significantly enhanced mechanical properties in its as-printed state for AA6061. These components exhibit an impressive yield strength (YS) of 233 MPa and ultimate tensile strength (UTS) of 310 MPa while maintaining a ductility of approximately 10 %. This performance surpasses that of commercial AA6061 and other Al-Si alloys, establishing it as a high-strength material suitable for various applications.
{"title":"Nanoparticle-enabled additive manufacturing of high strength 6061 aluminum alloy via Laser Powder Bed Fusion","authors":"Tianqi Zheng , Changyu Ma , Alexander Killips , Bingbing Li , Xiaochun Li","doi":"10.1016/j.mfglet.2024.09.093","DOIUrl":"10.1016/j.mfglet.2024.09.093","url":null,"abstract":"<div><div>Wrought aluminum alloy AA6061 is widely used in automotive, aerospace, and other industries due to its good properties, including high strength, excellent corrosion resistance, and good weldability. However, when using Laser Powder Bed Fusion (LPBF) for AA6061, hot cracking becomes a serious problem. In this work, AA6061 powder with internally dispersed nanoparticles has been adopted in a LPBF process. Through optimization of printing parameters, components with minimal porosity (less than 0.5 %) have been successfully produced without cracks. Additionally, by employing a chessboard printing strategy to create finely detailed cellular and grain structures, we have achieved significantly enhanced mechanical properties in its as-printed state for AA6061. These components exhibit an impressive yield strength (YS) of 233 MPa and ultimate tensile strength (UTS) of 310 MPa while maintaining a ductility of approximately 10 %. This performance surpasses that of commercial AA6061 and other Al-Si alloys, establishing it as a high-strength material suitable for various applications.</div></div>","PeriodicalId":38186,"journal":{"name":"Manufacturing Letters","volume":"41 ","pages":"Pages 753-757"},"PeriodicalIF":1.9,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142434286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01DOI: 10.1016/j.mfglet.2024.09.097
Tavila Sharmin , Rohan Shirwaiker
Auxetic scaffolds fabricated via additive manufacturing can enable cyclic mechanical stimulation to promote the biomechanical functionalization of engineered tissues. Typical designs of additively manufactured scaffolds used in tissue engineering literature (e.g., 0/90˚ strand laydown) are not amenable to cyclic loading due to their rigidity, which is in part due to the high stiffness of biopolymers such as polycaprolactone (PCL). Auxetic scaffolds can help overcome this due to their design-induced elasticity while recapitulating negative Poisson’s ratios seen in various natural tissues. In this study, we investigated the effects of auxetic design patterns and unit cell sizes on the mechanical properties of 3D bioplotted PCL scaffolds. First, we assessed the monotonic tensile properties of two auxetic patterns – re-entrant honeycomb and missing rib (unit cell = 3 × 3 mm2 for both) – in comparison to a uniaxial control (0/0˚ strand laydown) using finite element analysis (FEA) and experimental design (n = 3/group). The results showed that the scaffold design significantly impacted scaffold elasticity (p < 0.05), with the missing rib auxetic design demonstrating significantly higher yield strain (48.2 %) compared to the re-entrant honeycomb design (11.0 %) and the control (4.8 %). The missing rib design also possessed significantly lower elastic modulus and tensile strength (11.5 MPa/g and 10 MPa/g, respectively) compared to the re-entrant honeycomb (58 MPa/g and 35.7 MPa/g, respectively) (p < 0.05). For the missing rib design, we further investigated the effect of unit cell size (2 × 2, 3 × 2, 3 × 3 mm2) on the mechanical properties. Both 3 × 2 and 3 × 3 mm2 unit cell scaffolds (n = 3/group) possessed similar mechanical properties whereas the 2 × 2 mm2 unit cell scaffolds possessed significantly lower yield strain and higher elastic modulus and tensile strength (p < 0.05). The missing rib auxetic scaffolds were also tested under tensile cyclic loading for up to 6000 cycles at 10 % of maximum strain at 0.5 Hz. The 2 × 2 mm2 unit cell scaffolds degraded significantly faster than the other two groups. Overall, the 3 × 2 mm2 unit cell scaffolds performed better under cyclic loading in terms of maintaining their tensile strength. Finally, biocompatibility testing of the missing rib 3 × 2 mm2 unit cell scaffolds demonstrated their ability to support the adhesion and viability of fibroblast cells. In future, this knowledge will be leveraged to engineer scaffolds for connective tissues such as tendons and cardiac muscle.
{"title":"Assessing design-induced elasticity of 3D printed auxetic scaffolds for tissue engineering applications","authors":"Tavila Sharmin , Rohan Shirwaiker","doi":"10.1016/j.mfglet.2024.09.097","DOIUrl":"10.1016/j.mfglet.2024.09.097","url":null,"abstract":"<div><div>Auxetic scaffolds fabricated via additive manufacturing can enable cyclic mechanical stimulation to promote the biomechanical functionalization of engineered tissues. Typical designs of additively manufactured scaffolds used in tissue engineering literature (e.g., 0/90˚ strand laydown) are not amenable to cyclic loading due to their rigidity, which is in part due to the high stiffness of biopolymers such as polycaprolactone (PCL). Auxetic scaffolds can help overcome this due to their design-induced elasticity while recapitulating negative Poisson’s ratios seen in various natural tissues. In this study, we investigated the effects of auxetic design patterns and unit cell sizes on the mechanical properties of 3D bioplotted PCL scaffolds. First, we assessed the monotonic tensile properties of two auxetic patterns – re-entrant honeycomb and missing rib (unit cell = 3 × 3 mm<sup>2</sup> for both) – in comparison to a uniaxial control (0/0˚ strand laydown) using finite element analysis (FEA) and experimental design (n = 3/group). The results showed that the scaffold design significantly impacted scaffold elasticity (p < 0.05), with the missing rib auxetic design demonstrating significantly higher yield strain (48.2 %) compared to the re-entrant honeycomb design (11.0 %) and the control (4.8 %). The missing rib design also possessed significantly lower elastic modulus and tensile strength (11.5 MPa/g and 10 MPa/g, respectively) compared to the re-entrant honeycomb (58 MPa/g and 35.7 MPa/g, respectively) (p < 0.05). For the missing rib design, we further investigated the effect of unit cell size (2 × 2, 3 × 2, 3 × 3 mm<sup>2</sup>) on the mechanical properties. Both 3 × 2 and 3 × 3 mm<sup>2</sup> unit cell scaffolds (n = 3/group) possessed similar mechanical properties whereas the 2 × 2 mm<sup>2</sup> unit cell scaffolds possessed significantly lower yield strain and higher elastic modulus and tensile strength (p < 0.05). The missing rib auxetic scaffolds were also tested under tensile cyclic loading for up to 6000 cycles at 10 % of maximum strain at 0.5 Hz. The 2 × 2 mm<sup>2</sup> unit cell scaffolds degraded significantly faster than the other two groups. Overall, the 3 × 2 mm<sup>2</sup> unit cell scaffolds performed better under cyclic loading in terms of maintaining their tensile strength. Finally, biocompatibility testing of the missing rib 3 × 2 mm<sup>2</sup> unit cell scaffolds demonstrated their ability to support the adhesion and viability of fibroblast cells. In future, this knowledge will be leveraged to engineer scaffolds for connective tissues such as tendons and cardiac muscle.</div></div>","PeriodicalId":38186,"journal":{"name":"Manufacturing Letters","volume":"41 ","pages":"Pages 780-786"},"PeriodicalIF":1.9,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142434290","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01DOI: 10.1016/j.mfglet.2024.09.010
Wei Li , Barrie R. Nault
Given stochastic disturbances, such as variation in processing times, robust scheduling is recommended over optimal scheduling for production. Different from optimal scheduling that seeks an optimal solution to a key performance indicator (KPI), which relates to the average of a KPI, robust scheduling is to minimize the largest deviation from the optimum for the worst-case scenarios, which relates to the variance of a KPI. However, minimizing the variance does not necessarily optimize the average of a KPI. As one of the fundamental KPIs in production scheduling, total completion time (TCT) drives many other KPIs, such as average flow time, waiting time, due dates, and length of stay. Stochastic processing times and NP-hardness to minimize the variance of TCT, i.e., , are two challenges in production scheduling. To investigate the trade-offs between optimal and robust scheduling, we apply the differentiation method to analyze the first and second moments of TCT. In our approach, we use three statistical measures for processing times, which are the lower bound, the expected value, and the upper bound. We also use three terms for sequencing, which are the processing time of the initial job, the processing time of a job in the current position i of a sequence, and the difference of processing times between two adjacent jobs. Applying the three measures for processing times to each of the three independent terms for sequencing, we generate sequences to analyze the dynamics of VTCT. Through numerical analysis in our case studies, we show that our sequencing scheme can generate optimal solutions to , and solid variation ranges of VTCT. Consequently, we can not only balance the trade-offs between and , but also analyze the trade-offs between optimal scheduling focusing on the first-moment of a KPI and robust scheduling focusing on the second moment. Moreover, our analysis approach using the differentiation method is unique for production scheduling, which enables us to develop analytical methods and heuristics for balancing trade-offs between optimal and robust scheduling.
{"title":"Trade-offs between optimal and robust scheduling in one-stage production","authors":"Wei Li , Barrie R. Nault","doi":"10.1016/j.mfglet.2024.09.010","DOIUrl":"10.1016/j.mfglet.2024.09.010","url":null,"abstract":"<div><div>Given stochastic disturbances, such as variation in processing times, robust scheduling is recommended over optimal scheduling for production. Different from optimal scheduling that seeks an optimal solution to a key performance indicator (KPI), which relates to the average of a KPI, robust scheduling is to minimize the largest deviation from the optimum for the worst-case scenarios, which relates to the variance of a KPI. However, minimizing the variance does not necessarily optimize the average of a KPI. As one of the fundamental KPIs in production scheduling, total completion time (<em>TCT</em>) drives many other KPIs, such as average flow time, waiting time, due dates, and length of stay. Stochastic processing times and <em>NP</em>-hardness to minimize the variance of <em>TCT</em>, i.e., <span><math><mrow><mi>min</mi><mo>(</mo><mi>VTCT</mi><mo>)</mo></mrow></math></span>, are two challenges in production scheduling. To investigate the trade-offs between optimal and robust scheduling, we apply the differentiation method to analyze the first and second moments of <em>TCT</em>. In our approach, we use three statistical measures for processing times, which are the lower bound, the expected value, and the upper bound. We also use three terms for sequencing, which are <span><math><mrow><mi>x</mi><mo>(</mo><mn>1</mn><mo>)</mo></mrow></math></span> the processing time of the initial job, <span><math><mrow><mi>x</mi><mo>(</mo><mi>i</mi><mo>)</mo></mrow></math></span> the processing time of a job in the current position <em>i</em> of a sequence, and <span><math><mrow><mi>x</mi><mo>′</mo><mo>(</mo><mi>i</mi><mo>)</mo></mrow></math></span> the difference of processing times between two adjacent jobs. Applying the three measures for processing times to each of the three independent terms for sequencing, we generate <span><math><mrow><mn>27</mn><mo>=</mo><mn>3</mn><mo>·</mo><mn>3</mn><mo>·</mo><mn>3</mn></mrow></math></span> sequences to analyze the dynamics of <em>VTCT</em>. Through numerical analysis in our case studies, we show that our sequencing scheme can generate optimal solutions to <span><math><mrow><mi>min</mi><mo>(</mo><mi>TCT</mi><mo>)</mo></mrow></math></span>, and solid variation ranges of <em>VTCT</em>. Consequently, we can not only balance the trade-offs between <span><math><mrow><mi>min</mi><mo>(</mo><mi>TCT</mi><mo>)</mo></mrow></math></span> and <span><math><mrow><mi>min</mi><mo>(</mo><mi>VTCT</mi><mo>)</mo></mrow></math></span>, but also analyze the trade-offs between optimal scheduling focusing on the first-moment of a KPI and robust scheduling focusing on the second moment. Moreover, our analysis approach using the differentiation method is unique for production scheduling, which enables us to develop analytical methods and heuristics for balancing trade-offs between optimal and robust scheduling.</div></div>","PeriodicalId":38186,"journal":{"name":"Manufacturing Letters","volume":"41 ","pages":"Pages 63-72"},"PeriodicalIF":1.9,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142434340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01DOI: 10.1016/j.mfglet.2024.09.080
Nishant Ojal , Ryan Copenhaver , Harish P. Cherukuri , Tony L. Schmitz , Kyle T. Devlugt , Adam W. Jaycox , Kyle Beith
This paper describes a full-scale, three-dimensional coupled smoothed particle hydrodynamics (SPH) and finite element model for modulated tool path (MTP) turning. The chip breaking mechanism due to modulated motion of the tool is demonstrated by the developed machining model. In contrast, the simulation of conventional turning with the same machining conditions predicts long continuous chips. The cutting force predicted by the simulation is validated with a mechanistic force model based on the instantaneous chip thickness. This work expands the capabilities of machining simulations to predict complex machining phenomena such as MTP turning through a full-scale realistic simulation. The encouraging simulation results show the potential to study more complex phenomena, such as evaluating the parameters of tool path modulation, simulating ultrasonic machining, and studying machining stability.
{"title":"Modeling modulated tool path turning using coupled smoothed particle hydrodynamics and finite element method","authors":"Nishant Ojal , Ryan Copenhaver , Harish P. Cherukuri , Tony L. Schmitz , Kyle T. Devlugt , Adam W. Jaycox , Kyle Beith","doi":"10.1016/j.mfglet.2024.09.080","DOIUrl":"10.1016/j.mfglet.2024.09.080","url":null,"abstract":"<div><div>This paper describes a full-scale, three-dimensional coupled smoothed particle hydrodynamics (SPH) and finite element model for modulated tool path (MTP) turning. The chip breaking mechanism due to modulated motion of the tool is demonstrated by the developed machining model. In contrast, the simulation of conventional turning with the same machining conditions predicts long continuous chips. The cutting force predicted by the simulation is validated with a mechanistic force model based on the instantaneous chip thickness. This work expands the capabilities of machining simulations to predict complex machining phenomena such as MTP turning through a full-scale realistic simulation. The encouraging simulation results show the potential to study more complex phenomena, such as evaluating the parameters of tool path modulation, simulating ultrasonic machining, and studying machining stability.</div></div>","PeriodicalId":38186,"journal":{"name":"Manufacturing Letters","volume":"41 ","pages":"Pages 626-632"},"PeriodicalIF":1.9,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142434352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01DOI: 10.1016/j.mfglet.2024.09.023
Salil Bapat , Nithya Srimurugan , Albert J. Patrick , Sathyan Subbiah , Ajay P. Malshe
Commerce, long-term habitation, and far-location explorations are the objectives of the next space era, also called Space 2.0. These objectives are the focus of in-space servicing, assembly, and manufacturing (ISAM) research. Current research in this area is focused on demonstrating various manufacturing processes under microgravity using the International Space Station (ISS) as a platform and relies on an Earth-based supply chain. Building operational infrastructure and supply chains enabling in-space manufacturing is critical for the sustained growth of ISAM to meet the goals of Space 2.0. This paper is specifically focused on discussing the need and potential architecture for a maintenance factory in space to enable servicing, maintenance, and repairs in space environments. Space presents a hostile environment and a new set of challenges to establish a robust infrastructure necessary for supporting these objectives. The realization of such an infrastructure, including physical and digital footprints, is demanding new manufacturing science and engineering tools and platforms for maintenance. The authors present requirements of a robust maintenance platform, called a “factory in space” to deliver multi-functional maintenance service station(s) across various operational points in space such as low-earth orbit, lunar surface, and Martian surface. Such factories are projected to be an essential part of the in-space infrastructure for short as well as long-term commerce, habitation, and exploration. A critical analysis of this concept is proposed through an analysis of the state of the art, boundary conditions in space and requirements of maintenance, the role of manufacturing, and the design as well as sustainability considerations for a maintenance factory in space.
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