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.

This contribution deals with the study of cut surface after the abrasive water jet application on the material Maraging Steel MS-1, prepared in the form of 3D printing method Direct Metal Laser Sintering. The aim of the study is to point out the morphology of the cut plane under the use of various technological parameters, like feed rate of machining and abrasive mass flow at the constant cut pressure. For the track morphology monitoring after the abrasive water jet application, scanning electron microscope SEM MIRA 3, f. Tescan, was used. For the identification of observed particles stabbed in the cut track, chemical composition EDX analysis was used.

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.

With the rise of additive manufacturing (AM) technologies, a numerous limitations in conventional manufacturing have been circumvented. Additive manufacturing uses layer-by-layer fabrication of three-dimensional physical models directly from a computeraided design (CAD) model. The CAD design is transformed into horizontal cross-section layers that are stacked together in physical space until the physical model is completed. This process can be used to directly manufacture tools for injection molding or for an y other technology that requires a specific cavity shape to produce a part. This is referred to as Rapid Tooling (RT) and one of the up and coming
AM technologies is the resin based stereolithography (SLA).
An increasing number of companies are starting to develop desktop machines that utilize this technology and their low cost an d high speed changes the design workflow. As a printing technology, SLA creates parts with a smooth surface finish which is ideal for applications such as investment casting for developing jewelry or rapid tooling for injection molding.
The development of rapid tools using SLA usually requires more rigid materials which can withstand higher temperatures and stresses and part models that need to have more accurate dimensions in order for a precise part to be produced from that specific tool. Even though models created by SLA have more isotropic characteristics compared to other 3D printing technologies, there are still some variations linked to the process parameters. This paper covers how orientation of the model on the build plate impacts the pa rt accuracy and the tensile strength of the models. The effects of different post-processing procedures after SLA printing are also taken into consideration, since most resins need to be UV cured after 3D printing in order to achieve maximum mechanical strength.
This paper gives designers and engineers better understanding on the final properties of the models and the tolerances that have to be taken into consideration when designing parts intended to be manufactured via SLA 3D printing.

Additive manufacturing is an established production method to realize Direct Digital Manufacturing in Industry 4.0. Especially for metal components, production requires high investment sums and high levels of know-how in the organisation. To make the advantages of the technology accessible even without high initial investment costs, co-called online hubs became an external and decentralised alternative to additive in-house production. After uploading the geometry to the online portals, material and post processing can be selected. The hub gives the customer a direct pricing response which is one of the main economic indicators for a purchase decision. The present paper focuses on the influence of the order quantity and the complexity of the components on the price algorithm. Therefore, sample parts of varying complexity and sizes are developed and uploaded to analyse data. Based on the in-depth findings of the study, the results are discussed.

The article deals with the use of CAD software and additive technology to produce a simple, low-cost mechanical finger prosthesis. The goal was to use SOLIDWORKS and Cura software to design and manufacture an index finger prosthesis from PLA (polylactic acid) material, using an FFF (Fused Filament Fabrication) desktop 3D printer Bq WitBox. The mechanical finger prosthesis is used for flexion and extension performance of the missing joints to enable lost gripping function. The designed prosthetic finger has a simple construction consisting of components made on a 3D printer and its movement functions are initiated by specifically attached cable system. The practical part of the paper contains procedures for prototype and final version design, manufacturing and testing. The prototype was designed to imitate healthy finger digits movement initiated by the specific cable system. Final version of the finger prosthesis has been designed after the successful flexion/extension system testing. The design of the components was modified to resemble a healthy finger and a socket has been added to the prosthesis. Flexion and extension performance of the prosthesis was tested using cables of different diameters. After summarizing the results, it has been confirmed that the prosthesis can be easily applied to the arm and its dimensions, construction and movement correspond to an anatomically healthy finger and that 3D printing is a technology suitable for efficient and fast production of individual prosthesis components, which is an indisputable advantage compared to the traditional method of prosthesis production.

This paper covers the advanced Additive Manufacturing (AM) techniques used to fabricate prostethic and orthotic devices. It reviews the available literature and summarizes the advances in medicine, computing and engineering that have led to the development of currently available prostheses. Some of the open-source bionic hands and other available prosthesis are shown, as well as the technologies and materials which are used to manufacture the parts. Since prototyping, combined with the possibility for easy maintenance and repair, is very attractive for prosthesis design, as a conclusion we summarize and discuss some of the key areas that could lead to improvements in bionic limb functionality and use.

Virtual prototypes or virtual 3D models of complex armament parts reduce costs and production time with minimal risk of hidden flaws, testing and analyzing the construction before creating real physical prototypes or optimizing parameters in parallel with the physical prototypes. The report presents the possibility of rapid prototyping through the virtual 3D model of the SPG-9 breech and using additive manufacturing to obtain a functioning physical prototype.

This paper covers the advanced Additive Manufacturing (AM) techniques applied to injection mold design and production. Its aim is to do a comprehensive analysis on what AM is doing for the recent and future perspectives in the field of mold’s production.

Further analyses are done on the possible use of Rapid Tooling (RT) techniques based on AM technologies. These include plastic mold inserts made using high strength polymer resins and metal-based technologies for direct tooling work.

Moreover, the work also reviews conformal cooling channel design based on laser sintering AM technologies and its effect in improving mold cooling efficiency to reduce cycle times, which is an important issue in the injection molding process.

Finally, a brief techno-economical analysis is presented, as well as a comparison between the two different types of molds – the conventional ones, and molds produced by rapid tooling. The conclusions leads toward future usage of RT and AM in the mold design and
production.

In this paper, the capacity of additive manufacturing in the medical engineering will be considered in order the fourth industrial revolution, industry 4.0. The benefits of additive manufacturing, particularly individualization and sustainability, will be discussed and the particular demands of medical engineering are mentioned in relating to the manufacturing technology. Also, the challenges and technical lacks of the technology, mechanical properties, will be analyzed due to the scientific experiments and technical reports. The solutions for the problems are considered briefly and the alternative systems or processes will be obtained regarding the medical application. This research presenting the starting steps of the new project which is planned for next years, in the Institute of Materials and Processes, IMP, at Karlsruhe University of Applied Sciences.