Problems and Constraints Involved in the Injection Moulding Process of Biocomposites: A Review

Biocomposite materials have revolutionized the engineering field, predominantly in manufacturing applications, where these materials were widely used as an alternative to the metal-based structural body or component. Since conventional materials have caused various pollution problems to the ecosystem, innovative efforts have been taken to develop the based product on natural materials composites but presently are not fully explored yet. Most issues raised are due to the lack of expertise in addressing some of the problems and constraints related to preparing feedstock materials involved in the injection moulding technique. The injectability process of the biocomposite material significantly depends on the early stage of feedstock preparation. The preparation steps should be considering the detailed characterization of the composite material, the effectiveness of the mixing method, the identification of the feedstock's flowability properties, and the appropriate processing parameters used. This review manuscript has a significant contribution to researchers interested in furthering the application of biocomposite-based materials, particularly in plastics injection moulding technology for manufacturing and processing engineering.

Manufacturing of Nanocomposites via Powder Injection Molding: Focusing on Thermal Management Systems—A Review

The rapid evolution of electronic and information technology has increased the performance of the electronic processors significantly. Achieving the optimal performance in a smart electronic device poses a serious challenge as the heat generated during operation will reduce the performance of the device which makes thermal management a determinant factor. Powder injection molding (PIM) is an appropriate and relatively new technology used for mass production of small delicate parts with complex shapes and desired properties. One of the latest advances in the PIM process is the production of metal matrix nanocomposites with huge industrial applications, particularly in electronics manufacturing. Manufacturing of efficient complex-shaped nanocomposites, as thermal management components (passive heatsink), could be achieved through the PIM process. On the other hand, what could pose a challenge is the presence of nanoparticles affecting on the different stages of PIM process including feedstock preparation, molding, debinding, and sintering. In this paper, the effect of nanoparticles on different stages of PIM for the production of heatsinks is investigated. Then, the manufacturing of Cu-, Al-, and Mg-based nanocomposites by powder injection molding, as heatsinks, is reviewed followed by investigating the related advantages and limitations.

Development of Metal Powder Hot Embossing: A New Method for Micromanufacturing

Hot embossing is a small-scale, low-cost processing technology that can deliver products to the market in a short time. This microreplication technology is well established to produce polymeric components and has applications in several industrial sectors. The use of micropowder hot embossing in the production of metal components is an emerging and challenging process that, when compared to other typical technologies, brings some economic advantages in a volatile market with an increasing tendency to manufacture customized products. The main objective of this review is to analyze the potential of powder hot embossing and its developments in the production of metallic microparts/components. This technology requires four distinct steps: (1) production feedstock (preparation of mixtures), (2) hot embossing (shape forming), (3) debinding and (4) sintering. These steps are interrelated and influence the characteristics of the final metallic microparts. This study summarizes the approaches implemented for the use of different metallic powders and polymeric binder systems for the preparation of the feedstock, the mold materials and the critical conditions tested in the embossing step to produce green parts, and the production of the final parts through the application of debinding and sintering. Powder hot embossing is a viable replication technology that allows the production of new metallic microcomponents, contributing to the global scientific effort of miniaturizing manufacturing process, equipment and products. The merit of powder hot embossing for industrialization needs further development to assert itself in the market and compete with other micromanufacturing techniques.

The Microstructure and Selected Mechanical Properties of Al2O3 + 13 wt % TiO2 Plasma Sprayed Coatings

The Al2O3 + TiO2 coatings are of the interest of surface technology and tribology due to their good wear resistance and enhanced toughness comparing to pure Al2O3 coatings. However, the detailed effect of the used feedstock powder, is often neglected. Here, this work focuses on the deposition of Al2O3 + 13 wt % TiO2 coatings by atmospheric plasma spraying (APS) method as well as on their microstructure, phase composition and selected mechanical properties, in the reference to the route of the powder feedstock preparation. The commercial powder Metco 6221 in agglomerated and sintered form was used as a feedstock material during spraying, due to the fact that, so far, sintered or cladded powders are the most studied ones. The 2k + 1 spray experiment allowed to evaluate the influence of two variables, namely spray distance and torch linear velocity, on the coating microstructure. Afterwards, the coating adhesion was measured by the means of pull-off test. The correlations between Vickers microhardness, fracture toughness (Kc) as well as the coating morphology and phase composition were investigated. Finally, the dry sliding wear resistance was studied by using Ball-on-Disc method.

Investigation of Feedstock Preparation for Injection Molding of Oxide–Oxide Ceramic Composites

In this fundamental work, a series of experiments were performed to define the optimal amount of dispersant and solid content for feedstock with and without ceramic fibers (Nextel 610). Based on these fixed conditions, investigations were carried out to discover the effects of binder system, fiber sizing, and increasing fiber content on mixing and viscosity. In addition, the effects of kneading temperature and time, fiber sizing, and different binder systems on fiber length were investigated using a measuring mixer, high-pressure capillary rheometer, and microscopy. Stearic acid, as a dispersant, modified the particle surface and improved the rheological properties. Moreover, increasing the solid content in the feedstocks led to an exponential growth of final torque and relative viscosity, because of the increasing friction between particles. Paraffin wax (PW)- and polyethylene glycol (PEG)-based feedstocks showed different mixing behaviors and rheological results with increasing fiber, whereas PEG-based feedstocks had higher final torques and kneading energies without fibers, whilst PEG feedstocks displayed lower viscosities. Consequently, during kneading, the amount of fiber has been predominating over fiber length, and the effect of the binder, the kneading temperature, and time did not cause significant changes.

Investigation on Feedstock Preparation for Micro-Cemented Carbide Injection Molding

This research was focused on mixing of submicron cemented carbide (WC-Co-VC) powder and binder. WC-Co-VC powder particle size and morphology were analyzed by laser diffraction and field emission scanning electron microscopy. The WC-Co-VC powder was kneaded with a paraffin wax based binder system. Based on critical solid loading, the feedstock with different solid loadings between 49 to 51 vol.% was prepared. Finally, the flow behavior of different feedstocks was investigated. Morphology of powder revealed that the particles of powder are slightly agglomerated and irregular in shape. The result of mixing indicted that the torque value increases as the solid loading increase from 49 vol.% to 51 vol.%. The feedstock exhibited homogeneity and the powder particles are homogenously coated with binder. The feedstock with solid loading of 51 vol.% is sensitive to temperature and showed high viscosity values. The feedstock with solid loadings of 49 and 50 vol.% had good compatibility and flow characteristics.