Layer-by-Layer Deposition: A Promising Environmentally Benign Flame-Retardant Treatment for Cotton, Polyester, Polyamide and Blended Textiles

A detailed review of recent developments of layer-by-layer (LbL) deposition as a promising approach to reduce flammability of the most widely used fibers (cotton, polyester, polyamide and their blends) is presented. LbL deposition is an emerging green technology, showing numerous advantages over current commercially available finishing processes due to the use of water as a solvent for a variety of active substances. For flame-retardant (FR) purposes, different ingredients are able to build oppositely charged layers at very low concentrations in water (e.g., small organic molecules and macromolecules from renewable sources, inorganic compounds, metallic or oxide colloids, etc.). Since the layers on a textile substrate are bonded with pH and ion-sensitive electrostatic forces, the greatest technological drawback of LbL deposition for FR finishing is its non-resistance to washing cycles. Several possibilities of laundering durability improvements by different pre-treatments, as well as post-treatments to form covalent bonds between the layers, are presented in this review.

Conversion of a conventional to a digital lecture under the conditions of Covid19 – an example from a bachelor lecture on finishing, dyeing & printing

Due to the Covid-19 pandemic situation during the years 2020 and 2021, the necessity occurred to convert conventional university lectures into digital ones, to avoid personal contacts between people and by this minimizing the spreading of the disease. Beside lectures, also exams have to be transferred to minimize personal contacts. This paper reports on a lecture in a bachelor course with more than 100 students and its conversion to digital format. The lecture is related to textile finishing processes – especially to dyeing and printing. The experience get during the digital lecture are compared with the results gained during the last decade with the same lecture in conventional style. Main tools of the digital format are video conferences and digital worksheets. Challenging are the contact to students by e-mail and the time management of the students especially during the final digital homework. In conclusion, digital lecture and exam are valuable tools to increase the number of participating students and their success in the exam. These tools could be also used successfully in post-corona times especially for lectures given for experienced students in higher semester.

Analysis and characterization of additive manufacturing processes

Recently, additive manufacturing (AM) processes have expanded rapidly in various fields of the industry because they offer design freedom, involve layer-by-layer construction from a computerized 3D model (minimizing material consumption), and allow the manufacture of parts with complex geometry (thus offering the possibility of producing custom parts). Also, they provide the advantage of a short time to make the final parts, do not involve the need for auxiliary resources (cutting tools, lighting fixtures or coolants) and have a low impact on the environment. However, the aspects that make these technologies not yet widely used in industry are poor surface quality of parts, uncertainty about the mechanical properties of products and low productivity. Research on the physical phenomena associated with additive manufacturing processes is necessary for proper control of the phenomena of melting, solidification, vaporization and heat transfer. This paper addresses the relevant additive manufacturing processes and their applications and analyzes the advantages and disadvantages of AM processes compared to conventional production processes. For the aerospace industry, these technologies offer possibilities for manufacturing lighter structures to reduce weight, but improvements in precision must be sought to eliminate the need for finishing processes.

INTEGRATION OF MAGNETIC MATERIALS WITH ACTUATOR ROLE ON TEXTILE SUPPORTS

Magnetic textile materials represent a new category of smart materials, whose properties are obtained either by adding magnetic materials during the technological processes of obtaining fibres and yarns, either by applying some magnetic materials on textile surfaces during the chemical finishing processes (electroless plating, electroplating, magnetron sputtering). Therefore, by adding magnetic nano powders in the spinning solution, fibres with magnetic properties are obtained, by adding metallic fibres, with magnetic properties, during the spinning process, magnetic yarns are obtained, and by the insertion of a certain percent of metallic/magnetic yarns during the weaving or knitting process, textile materials with magnetic properties are obtained. Thus, magnetic textile materials will possess the uniqueness of a textile structure due to specific features as flexibility, breathability or lightweight, but at the same time, also the magnetic properties necessary in multiple applications such as magnetic sensors, actuators and electromagnetic shielding used in technical applications for defence, automotive and aerospace.

Edge finishing of large turbine casings using defined multi-edge and abrasive tools in automated cells

Automate finishing processes is a global challenge in several industrial sectors. Concretely, when dealing with aero-engine components, only simple finishing processes are automated nowadays. Most of the high-added value components manufactured are finished hand working, using deburring and polishing manual techniques. The driver of the proposed work is to achieve the necessary knowledge to introduce in a production line a complete finishing process for automated robotic deburring applications with low machinability materials (Inconel 718 in this case-study) on aero-engine casings with complex geometries: extruded casting bosses, internal features, etc. For this purpose, a three-step methodology is presented and analysed, providing a feasible workflow combining visual inspection for part positioning and edge location, with multi-edge solid tools and flexible abrasive tools to automate finishing operations, taking into account all process singularities. Results show that, using correct techniques, processes and parameters, an automated finishing process reducing operating time can be implemented in production lines.

Efficient Finishing of Laser Beam Melting Additive Manufactured Parts

In many cases, the functional performance of additively manufactured components can only be ensured by finishing the functional surfaces. Various methods are available for this purpose. This paper presents a procedure for selecting suitable processes for finishing laser beam melting additive–manufactured parts which is ultimately based on technological knowledge. It was experimentally proven that the use of several consecutive finishing processes is beneficial to achieve better surface quality. One finishing process chain was particularly effective (namely particle blasting/vibratory grinding/plasma electrolytic polishing) and the technological limits of this method were investigated in this study. The optimal parameters for this process combination ensured a surface roughness Sa < 1 µm.