Epoxy tooling: Technologies, developments, sustainability and future interest to industry 4.0

The technology of epoxy tooling, at present under continuous development, is used for the rapid manufacture of cost-effective tools for small batch production. It is a valid alternative with no need for expensive investment in metallic moulds for the development of new products. Current investigations are focused on improvements to the production system, improved tool performance, the cost reduction of moulds and tool manufacturing sustainability. In this paper, both the advantages and the disadvantages of epoxy tooling in injection moulding, wax injection, metal stamping and hot embossing are compared with conventional techniques. Following a brief introduction of rapid tooling technologies, the latest advances of epoxy tooling and their implementation in different manufacturing processes are all analysed. These developments refer to the production of new ad-hoc epoxy composites, increased productivity using conformal cooling channels, the reduction of the tooling manufacturing costs through waste reuse and the emerging industry 4.0 technologies for smart manufacturing and tooling. The main objective is to identify both the challenges facing epoxy tooling techniques and future research directions.

Microstructure and Mechanical Properties of TiB2/Al-Si Composites Fabricated by Electron Beam Rapid Manufacture

Bulky sample was fabricated by electron beam rapid manufacture (EBRM) technology, in which Ф1.6 mm wire of in-situ TiB2/Al-Si compositeswas selected as deposition metal, following byT6 heat treatment. The microstructure and mechanical properties of the bulky sample before and afterheat treatment were analyzed. Experimental results showed that the microstructure parallel to the weld was similar to that perpendicular to the weld. The microstructure of the as-deposited sample consisted of columnar and equiaxed grains, in which siliconwas distributed along the grain boundary and the grain size was about 30 μm. Besides, some TiB2 particles converged at the grain boundary. After T6 heat treatment, the average grain size of the sample increasedobviously.The average hardness of the sample was increased to 114.65 HV from 46.55 HV, an increase of 146%. The tensile strength of the sample increased to 326.66MPafrom 143.97 MPa, but the elongationdecreased compared with that of the as-deposited state. The tensile test showed that the mechanical properties of TiB2/Al-Si composites formed by electron beam rapid manufacture were isotropic before and after heat treatment.

Metal Machining—Recent Advances, Applications, and Challenges

Though new manufacturing processes that revolutionize the landscape regarding the rapid manufacture of parts have recently emerged, the machining process remains alive and up-to-date in this context, always presenting itself as a manufacturing process with several variants and allowing for high dimensional accuracy and high levels of surface finish [...]

Effect of graphite addition on mechanical properties of Al2O3 ceramics by directed laser deposition

In this article, graphite-reinforced Al2O3 ceramic materials were prepared by directed laser deposition. The effects of graphite addition (3–12 wt.%) on the phase composition, microhardness and fracture toughness of Al2O3 ceramics were studied. The results showed that the process was beneficial for maintaining uniform mixing of graphite and ceramics and thus could avoid the delamination caused by the difference in their densities. When adding 6% and 9% graphite, there were fewer internal defects in the samples, and no obvious new phase was generated after adding more graphite. The microhardness of 6% and 9% graphite-reinforced Al2O3 ceramics reached 18.84 and 18.86 GPa, respectively, and it was close to that of pure Al2O3 ceramics. The microhardness of all graphite-reinforced Al2O3 materials was lower than that of pure Al2O3 ceramics, but the value increased first and then decreased with addition of more graphite. The change in microhardness was similar to the trend of the number of defects, thus, these newly forming defects were an important factor affecting the microhardness. With an increase in graphite addition, the fracture toughness increased gradually. Furthermore, the fracture toughness reached 5.89 MPa m1/2 at 12% graphite addition, which was higher than 4.82 MPa m1/2 of pure Al2O3 ceramics. Adding more graphite was beneficial in enhancing the deflection and pinning of the graphite particles against cracks, resulting in higher fracture toughness. Graphite can improve the fracture toughness of Al2O3 ceramic, prepared by directed laser deposition, and the method can solve the uneven distribution caused by the difference in densities between the two powders. This also provides a new idea for the rapid manufacture of high-toughness ceramic parts at lower cost.

Kinematic Calibration and Data-Based Error Compensation of a Parallel Robot-Based Incremental Sheet Forming Machine

Incremental sheet forming is a state-of-the-art manufacturing process for the rapid manufacture of sheet metal components without the use of geometry-specific dies. In this paper, a novel ISF machine, based on a unique overconstrained parallel robot called the Tri-pyramid robot, is introduced. The inverse and forward kinematics of the machine are first analyzed and calibrated based on experimental measurements. In turn, to compensate the kinematic and compliance errors of the machine, a linear encoder system, developed to directly measure the end-effector positions, in conjunction with a neural network, trained to map encoder readings and spatial end-effector positions, is used. A feedback control law is then implemented to compensate the errors in real-time. Experimental results demonstrate that after calibration and error compensation the accuracy of the machine is improved tenfold, making it adequate for incremental forming applications.

Semi-Transparent Energy-Harvesting Solar Concentrator Windows Employing Infrared Transmission-Enhanced Glass and Large-Area Microstructured Diffractive Elements

We report on the study of energy-harvesting performance in medium-size (400 cm2) glass-based semitransparent solar concentrators employing edge-mounted photovoltaic modules. Systems using several different types of glazing system architecture and containing embedded diffractive structures are prepared and characterized. The technological approaches to the rapid manufacture of large-area diffractive elements suitable for use in solar window-type concentrators are described. These elements enable the internal deflection and partial trapping of light inside glass-based concentrator windows. We focus on uncovering the potential of pattern-transfer polymer-based soft lithography for enabling both the improved photon collection probability at solar cell surfaces, and the up-scaling of semitransparent solar window dimensions. Results of photovoltaic characterization of several solar concentrators employing different internal glazing-system structure and diffractive elements produced using different technologies are reported and discussed.