Semisolid Materials Processing: A Sustainability Perspective

Sustainable development is increasing in importance with restrictions on emission and carbon footprint. Similarly, both energy and resources efficiency are required, and at the same time, cost-efficiency is required. The current paper is focusing on carbon footprint, energy usage and material use efficiency of semisolid metal casting. A detailed analysis is made on the RheoMetal process, which is benchmarked to conventional HPDC casting. The analysis includes the gating system and the importance of the use of primary or secondary material. It furthermore includes a discussion of process yield and benefits based on process capability.

NUMERICAL ANALYSIS OF INFUSION STRATEGIES IN VACUUM ASSISTED RESIN TRANSFER MOLDING (VARTM) PROCESS

The Liquid composite Molding (LCM) process, such as Vacuum Assisted Resin Transfer Molding (VARTM), offers a fast and high-quality production of composites laminates. In the VARTM process, the simulation tool is found beneficial to predict and solve composite manufacturing issues. The part quality is dependent on the resin mold filling stage in the VARTM process. The infiltration of resin into a porous fibrous medium is taken place during the resin mold filling stage. The permeability has a crucial role during the resin mold filling stage. In this study, simulation of resin infusion through multiple injection gates is discussed. The various infusion schemes are simulated to identify defect-free composite manufacturing. The simulation approach is applied to five different stacking sequences of reinforcements. In this transient simulation study, permeability and resin viscosity is essential inputs for the resin flow. The simulation approach found that a gating scheme plays a vital role in mold filling time and defect-free composite fabrication. It is found that the line gating system can be useful for fast mold filling over the point gating system.

Analysis of Causes of Porosity Change of Castings under the Influence of Variable Biscuit Height in the Filling Chamber

Quality properties of castings produced in a die casting process correlate with porosity that is conditioned by a number of factors, which range from input melt quality to setup of technological factors of the die casting, and through structural design of the gating system. One of the primary parameters conditioning the inner soundness of the casting is the liquid metal dose per single operation of die casting. This paper examines the issue of metal dose. The experiments are performed with casting a gate system of an electromotor flange. The gating system examined was die cast with a variable volume of metal dose per single operation. The metal dose was adjusted to reach the height of a biscuit of 10, 20, and 30 mm. The examination of the inner homogeneity of the castings of the individual variants of gating systems with variable height of the biscuit proved that decreasing biscuit height results in an increase of porosity share in the casting volume. The programme MagmaSoft 5.4 revealed the main causes of changes in porosity share. The simulations detected that the change in biscuit height and volume of liquid metal directly influence thermal conditions of the melt in the filling chamber, and in the mould by means of the period in which the holding pressure action is influenced. Simultaneously, the melt flow mode in the sprues and gas entrapment in the melt volume are affected as well. Correlation of the factors consequently influences the final porosity of castings.

Assessment of the suitability of a gate design modification compared to the change in pressing velocity considering the distribution of gases in the casting volume

The qualitative properties of high pressure die castings are closely correlated with their internal structure, which is directly conditioned by the gas entrapment in the melt volume during the casting cycle. It is known that the gas entrapment in the volume of the melt and their subsequent distribution into the cast can be reduced by changing the technological parameters of the casting cycle or by the modification of the gating system design. The contribution addresses the issue of which variant of the gas content reduction is more efficient regarding the gas entrapment and the nature of the melt flow in the runners. The experiments are based on a real casting process. The established design solution of the gating system and the technological parameters setting are considered as a referential. Different gating system modifications were designed where the design modification is connected with the cross-section of a gate, in which the final acceleration of the melt flow occurs. The observed melt velocity in the gate is considered as a correlation factor, based on which the modification in the piston velocity is determined. The assessed parameter is the gas entrapment in the cast volume at the end of the filling phase. Assessment of the casting cycle and evaluation of experiments is performed using simulation program Magmasoft. Based on the performed analyses, it can be stated that the gate design modification will affect the filling regime of the die cavity by changing the melt velocity in gate, but the nature of the melt flow in runners remains unchanged. Modification of the piston velocity affects the filling regime of the die cavity, and also the nature of the melt flow as it passes through the runners, thereby promoting the gas entrapment in the melt volume. Therefore, it is necessary to pay an increased attention to the design of the gating system and only after debugging the design to proceed to the optimization of technological parameters.