A method for yield and cycle time improvements in Al alloy casting with enhanced conductivity steel for die construction

Abstract

A die for Al alloy casting must be designed to achieve the expected quality levels. Moreover, the casting unit cost must be regarded as the objective function to be minimised. It can be expressed as a function of the quantity of materials and energy to be used, cycle time and equipment investment. This work compares the performance of the die with inserts manufactured using the usual 1.2343 steel with that of the innovative 1.2383. The latter is considered due to its enhanced thermal conductivity, despite being more expensive. Simulation experiments are designed to evaluate different die layouts. The quality design solutions are evaluated against the cost objective function in order to identify the optimal die choice. A case study on gravity die casting (GDC) of an AlSi7Mg0.3 engine head shows faster solidification dynamics when using 1.2383 instead of 1.2343 steel. This reduces the feeder volume, thus increasing the production yield and speeding up the cycle time with a leverage effect. The higher investment cost for the inserts is rapidly returned thanks to the reduction in variable costs. The Return On Investment (ROI) with the improved die in the new solution is short compared with the life of the die.

Identification of Heat Transfer Parameters for Gravity Sand Casting Simulations

“…Different sands used for forming the mould exhibit specific thermal properties, significantly influencing heat transfer rates. Generally, the heat removal rate of a sand mould is lower than that of a permanent one manufactured from steel due to its lower volumetric heat capacity and thermal conductivity [3]. The volumetric heat capacity is lowered in direct proportion to the volume fraction of the pores and can be measured via differential scanning calorimetry.…”

Determination of linear expansion of AlSi10Mg aluminium alloy depending on external conditions during solidification

“…. As stated by the authors [ 26 ], SDAS is an important parameter for the designer of a cast part. If we measure this parameter in different parts of the casting we obtain values that are influenced by the heat dissipation rate.…”

“…This statement is acknowledged by other authors [ 27 , 28 , 29 , 30 ]. As study [ 26 ] describes that SDAS is approximately equivalent to the third root of the solidification time. Therefore, we can confidently conclude that the quality control of castings, with respect to the mechanical properties of the aluminium alloy, can be verified on microstructure images by measuring the SDAS parameter.…”

“…One of the main objectives is to reduce production costs, reduce scrap (castings discarded) and improve quality. This can be achieved by the correct mold parameters, where the designer must be knowledgeable in the areas of material physics, heat sharing and transfer, flow and solidification [ 26 , 32 , 33 ].…”