Manufacturing Branches Research Articles

MINIMALNA PLAĆA I UDIO RADA U PROIZVODNJI: DOKAZI IZ SJEVERNE MAKEDONIJE

The objective of the paper is to understand whether the minimum wage plays a role in the labor share in the manufacturing sector in North Macedonia. We decompose the movements of the labor share into those along a share-capital curve, shifts of this locus, and deviations from it. We use the capital-output ratio, total factor productivity and input prices to capture these factors, while the minimum wage is introduced as an element that shifts the curve. We estimate a panel of 20 manufacturing branches over the period 2012-2019 with FE, IV and system-GMM estimators. We find that the role of the minimum wage for the labor share is industry-specific. In labor-intensive and low-paid industries, it increases workers’ labor share, which corresponds to a complementarity between capital and labor. For capital-intensive branches, it reduces labor share, likely through the job loss channel and along a substitutability between labor and capital. This applies to both branches where foreign investment and heavy industry are integrated.

Measuring thermomechanical response of large-format printed polymer composite structures via digital image correlation

Large-format additive manufacturing (LFAM) is a branch of additive manufacturing (AM) research with the ability to create large structures typically measuring several meters in scale. LFAM is advantageous for tooling applications, not only because it offers the ability to create complex geometries not easily made using subtractive manufacturing processes, but the cost savings of pelletized feedstock used by these systems result in larger parts printed at faster speeds than traditional AM systems. Fiber reinforced polymer (FRP) is a commonly used feedstock material in LFAM structures because it reduces the distortion experienced during printing. However, FRP introduces highly anisotropic thermomechanical properties and contributes to a nonhomogeneous microstructure that can result in critical distortion of dimensions during tooling. Measuring the global thermomechanical response of LFAM structures requires a more representative method that accounts for not only anisotropic properties but also the nonhomogeneous nature of the final part. This is where traditional techniques to measure thermomechanical response, such as thermomechanical analysis (TMA), fall short as they assume homogeneity. This study evaluated the coefficient of thermal expansion (CTE) of LFAM structures as measured by TMA as compared to a novel digital image correlation oven (DIC Oven) system. The LFAM structures were made from 20 % by weight carbon fiber reinforced acrylonitrile butadiene styrene (CF-ABS). TMA measurements showed significant variations in CTE across a single LFAM bead, confirming the need for a global technique that captures overall thermomechanical response. The CTE values measured using the DIC Oven compared well to average TMA values obtained from localized measurements across the sample. The DIC Oven was also used to quantify the effects of different layer orientations on thermomechanical properties, which cannot be easily captured using TMA. A predictive model was also developed by using localized TMA values across an LFAM bead to predict the overall thermomechanical response of an LFAM structure.

Non-Planar Helical Path Generation Method for Laser Metal Deposition of Overhanging Thin-Walled Structures

Laser metal deposition is a branch of additive manufacturing that offers advantages over traditional manufacturing techniques for forming overhanging thin-walled metal parts. Previously, helical paths that were suitable for manufacturing such parts were not only limited to stacking material on a flat surface but were also fixed to the model boundaries. In order to solve these two problems to meet more complex process requirements, a non-planar helical path generation method is proposed for laser metal deposition. The method is based on the characteristics of the additive manufacturing process planning flow, which first slices the model using curved surfaces, then offsets the contours on the sliced layering, and finally generates continuous helical paths according to the contracted or expanded contours. In order to verify the feasibility of the method, hollow blades are formed on cylindrical surfaces following the planned paths. The results show that the proposed method is not only capable of assisting the laser metal deposition process to fabricate thin-walled structures on non-planar surfaces but also capable of freely adjusting the contour dimension.

‘5D PRINTING’ -THE NEW ERA IN DENTISTRY! -A NARRATIVE REVIEW

3D printing technology has a wide range of applications in various industries. It is widely used to produce complex 3D structures, but it has some limitations such as a limited amount of material, etc., which have been overcome with the introduction of 4D printing technology. In 4D printing, which involves time as a function and the combination of smart materials, this enables properties such as changing form and function.[1]Five-dimensional (5D) printing is a new branch of additive manufacturing (AM) with great potential to solve problems in engineering, medicine, dentistry and other related fields. It is the latest technological advancement used to produce complex and intricately shaped products, implants and devices with much better physical properties than those obtained by three-dimensional (3D) printing. The concept of 5D printing originated from William Yerazunis of the American University of Mitsubishi Electric Research Laboratories (MERL). In 5D printing, the printing plate also moves with the printing head during the printing process. in 3D printing techniques.[1]four-dimensional (4D) printing is the concept of using a smart material that can change the shape of a printed object over time as the temperature changes. [2] One of the advantages of 5D printing is the use of 25% less material than 3D printing. Five-dimensional printing is all about efficiently manufacturing this complex and curved structure with maximum strength. Using computer-aided design (CAD) data to produce super strong dental implants, orthodontic brackets, crowns, aligners, bridges and appliances. This CAD data is created using the dentist's 3D scanner / different design software.[1] 5D printing of five axes: [1], 1.X-axis ;2. Y-axis;3. Z axis; 4. Movable print head and 5. Movable printing base.5D printing is an advanced manufacturing technology that builds on the concept of 3D printing and adds customization options and features. While 3D printing requires the creation of three-dimensional objects layer by layer, 5D printing allows additional functions or features to be added to a printable object, often dynamically or responsively. its role in dentistry may be limited due to the newness of the technology.

Optimal industrial localization by using geographic information systems in the Nador province (northeast of Morocco)

Geographic Information Systems (GIS) is one of the most accurate, analytical, results-based, and decision-making tools. In this context, we will try to apply this technique to the best geographical locations for the construction of industrial units in the Nador region (north-eastern Morocco); But these units vary according to the manufacturing branches. The factors in control of light industries vary compared to heavy industries. considerations in the localization of building materials units vary compared to textile units. Thus, the criteria adopted in the localization of industrial units and their indicators differ. We decided to determine several factors that influence plant location, such as proximity to industrial units, proximity standards to cities, road density, topography nature, ports, raw materials, railways, and other factors. We find that the prime locations for establishing industrial facilities and developing industrial zones are the geographical regions neighboring the town of Selouane. The most significant areas for industrial investment cover approximately 1469 hectares, notably the flatlands to the west of Selouane. Additionally, there are well-suited areas such as Azgangan, Beni Ansar, and Zaio, totaling approximately 14,211 hectares in the outskirts of these town.

Response Surface Methodology (RSM) Approach for Optimizing the Processing Parameters of 316L SS in Directed Energy Deposition

Directed energy deposition (DED) is a crucial branch of additive manufacturing (AM), performing repairs, cladding, and processing of multi-material components. 316L austenitic stainless steel is widely used in applications such as the food, aerospace, automotive, marine, energy, biomedical, and nuclear reactor industries. Nevertheless, there is need for process parameter optimization and a comprehensive understanding of the individual and complex synergistic effects of process parameters on the geometry, microstructure, and properties of the deposited material or component. This is essential for ensuring repeatable manufacturing of parts across a single or series of platforms over time, or for minimizing defects such as porosity. In this study, the response surface methodology (RSM) and central composite design (CCD) were employed to investigate the effects of laser power, laser scan speed, and powder mass flow rate on layer thickness, density, microstructure, and microhardness of 316L steel processed by Laser Engineered Net Shaping (LENS®) DED. Polynomial empirical prediction models correlating the applied processing parameters and the studied responses were developed.

Practical implementation and experimental testing of control system for vibratory lapping-polishing machine

Vibratory technological machines are widely implemented in various branches of industrial, manufacturing, and mechanical engineering. Particularly, such equipment can be effectively used while conducting finishing technological operations, e.g., lapping and polishing of different machine parts. The present paper is focused on developing the control system for the novel design of a vibratory lapping-polishing machine driven by six solenoids. The main purpose consists in providing the circular trajectory of the working member and ensuring the machining uniformity at each point of the surface being treated. In such a case, it is proposed to actuate the solenoids with the specified time shift depending on the forced frequency needed to be provided. The duration of the signal actuating the solenoid is equal to one-sixth of the total duration of a cycle (period) of the working body oscillation. The corresponding control approach is developed and simulated in the Tinkercad application, while the control system is designed based on the Arduino software and hardware. In addition, the laboratory prototype of the vibratory lapping-polishing machine and the corresponding control system are implemented in practice. The performed experimental investigations substantiate the possibilities of generating the circular oscillations of the working member of the vibratory lapping-polishing machine. The obtained results may be useful for engineers and technologists dealing with control systems of various vibratory technological equipment based on electromagnetic and solenoid-type drives.

Phase evolution and mechanical properties of AlxCoCrFeNi high-entropy alloys by directed energy deposition

Directed energy deposition (DED), as an important branch of additive manufacturing (AM), has been widely used in the design and fabrication of high-entropy alloys (HEAs). Al is a common alloying element, it is critical to understand the effect of Al content on the phase evolution and mechanical properties of AlxCoCrFeNi HEAs. Here, a series of AlxCoCrFeNi (x = 0.2, 0.6 and 1.0) HEAs were manufactured by DED to investigate the alloying effect of Al on the phase evolution and mechanical properties. The phase transformation process was explored in conjunction with thermodynamic calculations. The results showed that the AlxCoCrFeNi HEAs transformed from single FCC phase (Al0.2) to FCC + BCC duplex phases (Al0.6), and then to single BCC phase (Al1.0) with the increase of Al content. Moreover, BCC phase further decomposed into the nanoscale two-phase structure containing ordered B2 phase and disordered A2 phase, which is beneficial to improve microhardness, yield strength and tensile strength. This work provides useful guidelines for the preparation and research of HEA systems with desirable properties.

China’s Capital Formation in the Volatile Time

China’s capital formation is an important theme, which, however, so far received only limited attention of researchers. The purpose of this study is to explore the major characteristics of the uniquely high rate of capital formation, close to 45% of GDP, that for many years has supported growth and structural changes in China. Data show that the official plans to alter the GDP structure by shifting the focus from investment to domestic consumption have not materialized. The shifts in the structure of capital investments demonstrate the country’s modernization strategy and tactics, but they have not led to significant changes in the key macro proportions, so export remains crucial for economic growth and investments. Today, the country concentrates capital expenditures in machine industry and in the advanced branches of manufacturing. The real estate segment experiences financial difficulties, which may cause its GDP share to decline. Shifts in manufacturing investments reflect the focus of the Chinese authorities’ decision-making, as well as their reaction to market signals. Although some proportions and correlation coefficients between profits, revenues and investments by industry remained fairly stable for a long time, the turbulent years of 2020-2022 prompted both declines and revivals in industrial investments with a changed structure. This paper offers an analysis of large statistical material on the sectors of the Chinese economy including manufacturing, its dynamics and structure, thus creating a clearer picture of the Chinese industries’ investment behavior as a way to adapt to new trends or withstand various shocks. The work has its limitations since statistical evidence is available on a smaller set of indicators than that for many other market economies.

A novel two-dimensional reflective coherent gradient sensor and its applications in residual deformation measurement of laser repaired metal components

Directed Energy Deposition (DED), known as an important branch of additive manufacturing, are becoming increasingly crucial in different industrial fields. However, this extreme manufacturing process may bring about quality issues for the DED product, and in-situ monitoring for characterizing mechanical parameters of thick DED products still needs to be improved. In this manuscript, for the convenient in-situ bidirectional residual deformation measurement of thick DED metal components, a novel two-dimensional coherent gradient sensor (2D-CGS) is established based on crossed Ronchi gratings. Firstly, the diffraction characteristic of the crossed Ronchi grating used in 2D-CGS is analyzed, and then the principles of 2D-CGS are analyzed in detail for bidirectional out-of-plane displacement gradient measurement. Furthermore, two temporal phase-shifting techniques: plane-parallel plate rotating (PPR) method and prism translation (PT) method, are extended from one dimension to 2D for improving the accuracy of 2D-CGS post-processing, named as 2D-PPR method and 2D-PT method. Verification experiment shows that the 2D-CGS system can synchronously measure the bidirectional curvature fields of the standard spherical reflector with the maximum relative error of 3.80%, which is equivalent to the accuracy of typical CGS. Finally, in the application of zig-zag deposited DED process, the bidirectional residual deformation fields of repaired components are in-situ monitored by portable 2D-CGS system, and the relationship of dwell time between adjacent tracks and the residual deformation is analyzed based on bidirectional centerline curvature on the bottom surface of substrate. A new parameter named as the orthotropic symmetry coefficient is defined based on curvature to analyze the full-field in-plane orthogonal anisotropy. Results show that both the degree of in-plane orthogonal anisotropy and value of residual deformation decreases with the increase of dwell time from 0 to 5 s, while varying a little with the dwell time exceeding 5 s, which also indicates the proposed parameter could well evaluate the degree of full-field orthotropic anisotropy. Meanwhile, the position of maximum curvature also gradually moves from the end toward the beginning in deposition direction. In summary, the proposed 2D-CGS method can measure the full-field bidirectional deformation in high efficiency, which may be promising in future in-situ monitoring applications.

A short review on SLM-processed Ti6Al4V composites

The advancements in computer-aided design, manufacturing, and additive manufacturing techniques attracted the researcher to apply various new methods with the unique combination of alloys and composites to design and develop complex parts. Among them the selective laser melting (SLM) process, a branch of additive manufacturing, and Ti6Al4V (Ti64) composite. Due to the better mechanical and corrosion resistance characteristics of Ti64 and its composites, they have been utilized for making various engineering parts related to jet engine fans of aero-engine, engine valves of automobiles, knee and hip joint endoprosthesis in the biomedical field, and corrosion resistance pipes in chemical industries. Also, more complex, net-shaped, and lattice-structured components can be fabricated by advancing the SLM process. The final quality of the parts manufactured from the SLM technique will depend on the fabrication process parameters followed. Many researchers have done research work on metal additive manufacturing by changing and optimizing the SLM process parameters such as laser power ( P), scanning speed ( v), hatch spacing ( d), and layer thickness ( h). Also, they have studied the effect of changes on the feedstock preparation, SLM process parameters, milling time of composite and post-heat treatment on the quality of Ti6Al4V composites. Therefore, a detailed review is needed to study the effect of the abovementioned parameters on the quality of metal additively manufactured parts through SLM. Hence, a short review is done on future challenges and opportunities of SLM-processed Ti6Al4V composites and reported in this article.

Surface morphology inspection for directed energy deposition using small dataset with transfer learning

Directed Energy Deposition (DED) is a branch of Additive Manufacturing (AM) that offers extraordinary controllability and the ability to rapidly shape materials directly into large parts with complex structures. Innovative applications of machine learning and neural network algorithms in additive manufacturing processes have recently been developed, but there are still several barriers to the development and practical application of this technology. The large amount of sample data required for visual inspection using a neural network framework leads to the problem of difficult and costly preparation of surface morphology data. In this study, a transfer learning approach based on a small dataset is proposed to detect surface morphology in the DED procedure. The approach proposed effectively and innovatively addresses the sample scarcity issue that arises during neural network training and eliminates the issue of having to recreate a sizable quantity of the matching surface sample data. It also effectively accelerates the model convergence process through the transfer learning method, which indirectly improves detection accuracy. This work selected a parametric transfer learning approach to train YOLOv7, a self-supervised object detection model, for transfer learning. The experiments utilized an open-source defective dataset (NEU-DEF) for transfer learning pretraining. The training was carried out in combination with a home-made object dataset of 240 small samples after transfer of the model parameters. The input to the model is image data and the output of the training is the classification of surface morphology. The results show that the transfer training model 2 pretrained with the Stochastic Gradient Descent (SGD) algorithm has high accuracy and precision, achieving a Mean Average Precision (MAP) value of 0.62. Transfer learning speeds up the feature extraction process by transferring the parameters of a pretrained model for a similar task directly into the current task model, resulting in improved detection performance.

Impacts of Laser Power and Scan Speed on Temperature Field and Molten Pool of ZL104 Aluminum Alloy Selective Laser Melting

Selective laser melting (SLM), a significant branch of laser additive manufacturing (LAM) technology, has become a popular topic of research in engineering, materials and many other disciplines. SLM can transform metallic powders directly into 3D components, which allows SLM to offer the unique flexibility of manufacturing parts with complex structures. The quality of the product is closely related to the characteristics of the temperature field, as well as that of the molten pool. Because of the high localized temperatures and the rapid cycles of melting and solidification during SLM, it’s difficult to monitor the temperature field in real time. Hence, numerical simulation is often used to study the SLM process. In this work, the SLM process of ZL104 aluminum alloy was simulated using the CFD method, and the influences of processing parameters, including laser power and scan speed, on the temperature field and the characteristics of the molten pool have been investigated. Results showed that when the laser power increased, the peak temperature of the molten pool also mounted, however, the maximum temperature of the molten pool fell as the scan speed rose. The dimensions of heat affected zone (HAZ), including the width and depth, increased with growing laser power, but decreased with the increase of scan speed.

Experimental determination of influences on a gauge block’s stack length

Gauge blocks are an important basis for maintaining traceability in dimensional metrology, used for calibrating length measuring instruments and for adjustments in all branches of manufacturing. Their important feature is that they can be wrung with small dimensional uncertainty. An overview of the factors influencing the accuracy of a stack length, such as the quality of the gauge blocks (grade, wear), surface preparation (cleaning and usage of a lubricant), wringing (way and time, temperature of hands and gloves) is given in the paper. Experiments for determining these influences were performed with a highly precise gauge block comparator. Proper selection of gauge blocks, preparation of their surfaces and oiling improve the accuracy of a stack length. Application of a lubricant, wiped with a dry cloth or paper towel, helps to wring them more easily, but its contribution to the stack length in the experiment was 0.1 µm for oil and 0.2 µm for grease. Temperature changes of gauge blocks were estimated by holding them, and, during wringing in well controlled air conditions, monitoring them to yield the empirical coefficients of their warming up. The results showed that usage of gloves reduces the warming up by approximately half, but still the stack must be stabilised in well controlled conditions for at least one hour if it is used for micrometre-level precise measurements.

Online Deformation Measurement of Laser Repair Substrate Based on Orthogonal Sampling Moiré

As an important branch of metal additive manufacturing, laser repair has broad application potential in the aerospace, automobile and ship building industries. In the process of laser repair, metal powder is introduced into the laser action area and heated to a molten state to form a molten pool, which moves on the component surface according to the preset scanning path. Additionally, the temperature of the repaired component changes dynamically with the movement of the molten pool, leading to the time-evolution of stress and deformation. Therefore, online deformation measurement for the repair process is essential for understanding the evolution mechanism of stress and deformation in laser repair. However, extreme environments such as ultra-high temperature, strong laser radiation and metal powder splashing exist during the laser repair, which bring great challenges for dynamic optical measurement. In this paper, an online deformation measurement system based on orthogonal sampling moiré for laser repair environment is developed, which is applied to measure the deformation field of the metal substrate during laser repair. In the measurement, laser repair is performed on a cantilever beam substrate and orthogonal grating is prepared on the side surface of the cantilever beam. The real-time grating images are recorded by an optical imaging system, in which a group of filter components are used to obtain optical images with high signal-to-noise ratio. Finally, the deformation field of the substrate during laser repair is calculated with the orthogonal sampling moiré method. The results show that the scanning path in the repair process has a significant influence on the distribution of residual deformation, which offers reference for optimizing parameters of laser repair.

Bank Competition, Combination of Industry and Finance, and Enterprise Innovation: Evidence from China

Bank competition promotes enterprises to obtain credit funds through market mechanisms, and a combination of industry and finance (CIF) has an important influence on establishing bank‐enterprise relationship. Based on data of 2,245 manufacturing enterprises and branches of commercial banks in China from 2007 to 2019, this research establishes a moderated mediation model to verify whether CIF has a moderating effect on bank competition on enterprise innovation. The results are as follows. First, bank competition can both directly and indirectly promote enterprise innovation by alleviating financing constraints. Second, CIF has no moderating effect on the direct effect of bank competition on enterprise innovation but has a negative moderating effect on the first half of mediating effect.

Polymer 4D printing: Advanced shape‐change and beyond

Abstract4D printing is an exciting branch of additive manufacturing. It relies on established 3D printing techniques to fabricate objects in much the same way. However, structures which fall into the 4D printed category have the ability to change with time, hence the “extra dimension.” The common perception of 4D printed objects is that of macroscopic single‐material structures limited to point‐to‐point shape change only, in response to either heat or water. However, in the area of polymer 4D printing, recent advancements challenge this understanding. A host of new polymeric materials have been designed which display a variety of wonderful effects brought about by unconventional stimuli, and advanced additive manufacturing techniques have been developed to accommodate them. As a result, the horizons of polymer 4D printing have been broadened beyond what was initially thought possible. In this review, we showcase the many studies which evolve the very definition of polymer 4D printing, and reveal emerging areas of research integral to its advancement.

Performance Assessment and Chip Morphology Evaluation of Austenitic Stainless Steel under Sustainable Machining Conditions

Sustainable manufacturing has received great attention in the last few decades for obtaining high quality products with minimal costs and minimal negative impacts on environment. Sustainable machining is one of the main sustainable manufacturing branches, which is concerned with improving environmental conditions, reducing power consumption, and minimizing machining costs. In the current study, the performance of three sustainable machining techniques, namely dry, compressed air cooling, and minimum quantity lubrication, is compared with conventional flood machining during the turning of austenitic stainless steel (Nitronic 60). This alloy is widely used in aerospace engine components, medical applications, gas power industries, and nuclear power systems due to its superior mechanical and thermal properties. Machining was performed using SiAlON ceramic tool with four different cutting speeds, feeds and a constant depth of cut. Consequently, various chip characteristics such as chip morphology, chip thickness, saw tooth distance and chip segmentation frequency were analyzed with both optical and scanning electron microscopes. Performance assessment was performed under the investigated cutting conditions. Our results show that the tool life under MQL machining are 138%, 72%, and 11% greater than dry, compressed air, and flooded conditions, respectively. The use of SiAlON ceramic tool results is more economically viable under the MQL environment as the overall machining cost per component is lower ($0.27) as compared to dry ($0.36), compressed air ($0.31), and flooded ($0.29) machining conditions. The minimum quantity lubrication technique outperformed the other investigated techniques in terms of eco-friendly aspects, economic feasibility, and technical viability to improve sustainability.

Numerical Homogenization of Multi-Layered Corrugated Cardboard with Creasing or Perforation.

The corrugated board packaging industry is increasingly using advanced numerical tools to design and estimate the load capacity of its products. This is why numerical analyses are becoming a common standard in this branch of manufacturing. Such trends cause either the use of advanced computational models that take into account the full 3D geometry of the flat and wavy layers of corrugated board, or the use of homogenization techniques to simplify the numerical model. The article presents theoretical considerations that extend the numerical homogenization technique already presented in our previous work. The proposed here homogenization procedure also takes into account the creasing and/or perforation of corrugated board (i.e., processes that undoubtedly weaken the stiffness and strength of the corrugated board locally). However, it is not always easy to estimate how exactly these processes affect the bending or torsional stiffness. What is known for sure is that the degradation of stiffness depends, among other things, on the type of cut, its shape, the depth of creasing as well as their position or direction in relation to the corrugation direction. The method proposed here can be successfully applied to model smeared degradation in a finite element or to define degraded interface stiffnesses on a crease line or a perforation line.

Parameter tuning process for a closed-loop pneumatic actuator

Pneumatic drives are light weight, small-sizes, simple to install and to maintain. Pneumatic drives have a robust design and operation. They are clean and cheap, have no temperature limitation, and so, they are preferred in many branches of manufacturing and process industry. The well-known pneumatic actuators are widely used in closed-loop positioning systems because of their dynamic performance and mechanical flexibility in different electro-mechanical systems arrangements. The goal of the paper is to find the parameters of a closed-loop pneumatic actuator so that a good dynamic behaviour of the system is obtained. The parametric tuning process is developed by using numerical simulation technique. So, it was seen that using a proportional controller, the pneumatic actuator has an asymptotic stability for different values of the proportional gain K p . Starting with K p = 8 the system remains stable, but oscillations of low amplitude appears.