International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

The growing environmental concern about plastic waste has prompted research into sustainable recycling of polymer, particularly for widely used polymers such as polyethylene from the spools used in the textile industry in the second half of the 20th century. This study investigates the feasibility and optimization of recycling Polypropylene to make filaments suited for 3D printing applications, notably Fused Deposition Modelling (FDM). The study is divided into three phases: collecting and preparing post-consumer Polypropylene spools, extruding recycled Polypropylene into filaments, and optimizing the filament for 3d printing using FDM Technology.
Polyethylene spools are cleaned, shredded, and treated to ensure consistent feedstock quality. The extrusion process entailed controlling factors like temperature, screw speed, and cooling rate to produce filaments with constant diameter with less distortion. Following material characterisation, the printability of recycled Polypropylene filaments was evaluated using an FDM 3D printer. The Taguchi method is used to carefully study the influence of printing parameters such as nozzle temperature, bed temperature, print speed, and layer height to determine optimal parameters. The printed examples showed reasonable dimensional accuracy and layer adhesion, with surface roughness values within acceptable limits for practical applications.
This thorough study plan focuses on recycled Polypropylene as a feasible and sustainable material for FDM 3D printing. The findings indicate that with proper optimization, recycled Polypropylene can match the performance requirements of a variety of applications, helping to reduce waste and promote the circular economy in additive manufacturing. Long-term performance testing and the development of recycling processes will be the primary focus of future research to improve the material’s characteristics and broaden its application range.

In this study, we aim to realize a methodology for designing the spinal column of a quadruped robot employing additive manufacturing techniques. Additive manufacturing processes have gained widespread usage owing to their ability to swiftly develop prototypes for research and actualize production-grade components. Our research commenced with the acquisition of vertebral dimensions sourced from real animals such as cheetahs. These dimensions were pivotal inputs for conducting kinematic analyses of the animal’s locomotion cycle.
Through meticulous kinematic analysis, it was delineated the various positions assumed by the spinal column throughout the locomotion cycle. Furthermore, we assessed the maximal force to which the spinal column could be subjected. This evaluation formed a robust foundation for exploring diverse modeling approaches to identify the optimal solutions. An innovative solution emerged through the utilization of a beam featuring a variable cross-section. This approach facilitated precise customization of the design to align with our specific requirements. To manufacture all requisite components for the spinal column, we employed a single 3D printer utilizing the Fused Deposition Modelling (FDM) technique with PLA material. To validate the computational methods, it was developed a sophisticated test bench. By juxtaposing theoretical predictions against tangible experimental data, it was affirmed the accuracy of the theoretical approach. This validation serves as a springboard for subsequent phases in the design and production processes of quadruped robots.

The most important areas of the industry, need products with short development stages. Additive manufacturing (AM) techniques, as Fused Deposition Modelling (FDM), are an integrated solution to the overall conception and product development cycles; the same competition is based on the development of new products with technological features, design and functional solutions in the shortest time. In this paper are discussed different process parameters for fused deposition modelling that affects the parts quality by using a low-cost 3D printer machine in order to produce an industrial product. The process parameters taken into the analysis, resulted effective in improving final parts quality.

Additional manufacturing (AM), commonly known as 3D printing, exists for 40 years, still evolving and improving. AM has gained great popularity in modern industries due to many advantages concerning conventional manufacturing technologies. Consequently, AM is one of nine pillars of the currently dominating industry trend – Industry 4.0. Initially, AM was mostly used for making models. Now, objects made by AM technologies, often are physical parts ready to be used as final products or to be installed as parts of assemblies in more complex systems. Because of that, in more applications, the mechanical properties of these parts have to be known for the purpose to determine load carrying capacity essential for their functionality. Mechanical properties are being tested using appropriate methods, specimens, and equipment. In order to obtain comparable and evaluable test results, the test procedures and means should be s tandardized. Therefore, there was a need to develop standards for testing materials used for AM. International standardization in the field of AM started 10 years ago. The international body for standardization ISO developed and published a certain number of standards, but this is just beginning. This paper discusses aspects of AM standardization in the field of testing the mechanical properties of materials for 3D printing using fused deposition modelling (FDM). As an illustration of the standard application, specimens were prepared for testing the tensile properties of plastic materials widely used in AM: PLA, PETG and ABS+.