Additive manufacturing technology has been developed in the manufacturing industry; however, limited choice of materials and low printing speeds in large-scale production make 3D printing challenging in the industry. Wood and cellulose-based materials have recently drawn a lot of attention for use as 3D printing materials due to their unique properties such as environmental friendliness, cost-effectiveness and abundancy. However, because these compounds are derived from various natural sources, their different particle sizes can result in low 3D printing quality. The objective of this study is to resolve the mentioned deficiencies in the packaging industry by designing a novel 3D printer nozzle based on the material extrusion method (FDM technique), which provides higher printing speed and enhanced quality for wood and cellulosebased materials. The packaging industry can significantly benefit from 3D printing technology for cellulosebased materials by producing high-quality recyclable economical packaging on a large scale according to the clients' demand. The proposed nozzle design enables selecting different geometrical cross-sections of the nozzle dies and any number of extrusion points along the nozzle die simultaneously during the 3D printing process. These capabilities lead to advanced performance and improved speed of 3D printing in large scale manufacturing. The proposed nozzle design provides a novel technique for 3D printing of plant-derived compounds with remarkable advantages such as providing selective variable extrusion and multiple nozzle dies. Compared to other existing 3D printing techniques, the proposed nozzle abilities make it a promising option with higher speed and better functionality for the packaging industry.INDEX TERMS 3D printing, wood printing, cellulose-based materials, extrusion technique, 3D printer nozzle, packaging industry.

Direct Metal Laser Sintering (DMLS) is an advanced additive manufacturing (AM) technique for the 3D printing of metals. This technology is also beneficial in the jewelry industry, where precious metals are used, and the design and price are determinative factors. In this paper, the metal 3D printing process for jewelry production is discussed. Four rings made of gold, silver, titanium, and stainless-steel 316L have been designed and fabricated by AM machine based on the DMLS technique. Proper geometry and parameters for rings and support structure were determined. Results showed that a reduced amount of powder was required for 3D printing of metal rings using a locally developed AM machine. Besides, appropriate geometry and parameters for a jewelry box with a complex design have been specified to be fabricated from stainless steel 316L by the same AM machine. The quality of the final produced parts using DMLS technology was not demonstrated inferior compared to the quality of parts built by conventional manufacturing methods. Furthermore, utilizing an electron microscope the microstructures of the fabricated parts were obtained and analyzed in detail before and after polishing on the polisher machine. Results revealed that the maximum homogeneous surface was obtained for the gold and titanium samples, while the surface of the samples of stainless steel and silver had internal cavities, pores, and other defects. Also, it was concluded that usage of gold and silver for the manufacturing of jewelry product that does not experience heavy loads is quite justified.INDEX TERMS Additive Manufacturing (AM), Direct Metal Laser Sintering (DMLS), microstructure analysis, jewelry design, precious metals, 3D printing.

The present paper compares the efficiency and dynamic behavior of a log crane while using two alternative transmissions. Firstly, the conventional mobile hydraulic valves with a load-sensing pump is used, and secondly, a novel electric-hydraulic energy converter and a direct driven hydraulic actuator is used. By applying lumped parameter models and the theory of centralized pressure, the hydraulic system models are constructed in MATLAB & Simulink environment. MathWorks Simscape Multibody is used in modeling of the multi-body system of the crane. The results of the simulation models are compared with those measured in the laboratory. Based on the verification results, such modes of operation in which the agreement between simulated results is the closest are selected for further investigation. The effectiveness of the system equipped with an electro-hydraulic converter is compared with that of the conventional system with a load sensing pump. Detailed models for components are given in the paper, and the results are discussed based on what obtained through simulation and experiments. The electric-hydraulic converter used in direct driven circuit is a novel prototype developed at LUT University. It has good power stiffness, and it provides good torque properties in a wide RPM area. The prototype is used in operating the lift or tilt cylinder, which is altered by using fast switching valves. The actual test circuit does not have electric storage. The ability of the converter to recover potential energy from the lifting system inertia is approximated in the efficiency comparisons.

This paper presents various perspectives on designing and implementing a communication platform for a teleoperated mobile robot. The deployment of a communication network for a mobile robot and the integration of robot components in the developed communication platform are discussed in this article. A Wi-Fi-based communication network has been established, and to secure remote control over long distances, Internet-based communication via the 4G protocol has been launched using a virtual private network setup. Since an unstable network can damage the robot or the surrounding environment, an algorithm has been developed to monitor the state of the network connection through different protocols. The developed algorithm is able to detect network failure independently of the wireless communication technology used and notify the system of any disruptive communication. The robot's primary reactions to connection failure have been programmed to keep the robot under control until the communication with the control station is restored. Various experiments were carried out to validate the performance of the designed algorithm and statistical analysis was performed for each experiment. One of the main contributions of this study is the development of an algorithm for communication between the mobile robot and the control station based on both Wi-Fi and 4G, which is capable to keep the robot behavior safe and reliable in the presence of an unstable network or connection failure.

Laser scribing is developing rapidly in industrial applications as a method of material processing, especially in areas that require high levels of precision. This technology provides functionality and efficiency improvements in the manufacturing of solar panels. Due to the premium quality and speed requirements of the laser scribing technology, monitoring of this process in real-time is critical in order to promptly detect defects in the manufacturing process. However, common monitoring systems have been developed for other laser processes, like laser welding, which are noticeably slower than the laser scribing process. The goal of this research was to investigate the possibility of using photodiodes for real-time monitoring of the laser scribing process for Copper Indium Gallium Selenide (CIGS) solar panels. Various monitoring setup configurations were designed, developed, and examined to determine the viable option for implementation as a defect detection platform. Using different photodiode positions, the intensity of the light and the photodiode induced voltage for diffuse and specular reflections were tested, and the practical pros and cons of applying each configuration were analyzed. The capability of the monitoring system to distinct the different layers of the scribed CIGS cell was also examined to assess the penetration depth of the scribe. In addition, by performing several experiments with different scribe thicknesses and analyzing oscilloscope measurements, the optimal placement of the photodiode for accurate tracing of the scribing path was determined and verified. Key aspects of development of such monitoring system for solar panel applications were identified through this research.

The objective of this study was to develop a novel real-time monitoring and control method for ultra-fast laser scribing processes utilizing spectrometer. Adjustment of laser process parameters such as laser power with high precision in real-time is critical in the laser engraving process due to the premium quality and speed requirements of the process. An online monitoring system was established using the Ocean Optics spectrometer, IPG ytterbium pulsed laser, and PXIe-8880 industrial computer. An algorithm for realtime control of the laser scribing process was developed based on the monitoring outcomes using LabVIEW® software. Experimental methods were performed to evaluate the reliability of the developed monitoring system and control algorithm. The sensitivity of the spectrometer was assessed by changing laser power, pulse length, and focal point position. A workpiece consisting of two different metals, including stainless steel SS304L and steel S355, was used to evaluate the performance of the developed algorithm when scribing moved from one material to another. Instant accurate setting of the laser power based on the variations in intensities of metals from 750 AU to 1400 AU validated the reliability of the algorithm.

Selective Laser Melting (SLM) is an advanced Additive Manufacturing (AM) technique for the 3D printing of metals. SLM process parameters and different types of defects that may appear during the manufacturing process affect the quality of the final product. Setting laser parameters and online defect detection contributes to improving the quality of parts fabricated through SLM technology. In this study, the effect of the process parameters on the properties of the product built by the SLM process was investigated, and an in-situ monitoring platform was developed to detect two types of defects during the SLM process. Different samples were built from stainless steel AISI 316 L powder, utilizing various laser process parameters. Using microscopy imaging technique, the melt structure features of the constructed samples were tested, and the results were analyzed. The dependency of porosity formation on laser process parameters and scan strategy was investigated. Moreover, hardness test was performed for all built samples. The platform developed for in-situ monitoring purposes includes an AM machine equipped with pulsed laser, camera, illumination system, and powerful industrial computer equipped with Cameral Link Adapter, FPGA, and Real-Time (RT) modules. An algorithm was designed using LabVIEW R software based on Particle Analysis (PA) to cease the process in the event of detection of defect in any fused layers. The first defect was caused by changing the laser spot diameter, which altered the energy intensity of the laser on the surface, and the second defect was created by the uneven thickness of powder on the platform. The monitoring system detected both defects and stopped the process immediately according to the designed algorithm. Images were taken from the melting process layer by layer using a high-performance camera.INDEX TERMS Additive manufacturing (AM), focal point position, in-situ monitoring, laser beam diameter, laser energy density, particle analysis (PA), powder thickness, selective laser melting (SLM).

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