Investigations for Statistically Controlled Hot Chamber Die Casting Solution of Aluminium Alloys

The purpose of the present investigations is to study the effect of processing parameters on statistically controlled hot chamber die casting solution for Al alloy. The study presented in this paper is based on a macro model (based on Taguchi design). Castings prepared at proposed parametric settings (as per macro model) have been investigated for functional validation of the parts. The study suggested significant improvement in dimensional accuracy (ΔD) at proposed parametric settings and the process was found to be under statistical control.

Mechanical Properties of Magnesium Die Castings Produced Utilizing Process Scrap

Magnesium alloys are one of the lightest of all the structural materials. Because of their excellent physical and mechanical properties the alloys have been used more and more often in various branches of industry. They are cast mainly (over 90%) on cold and hot chamber die casting machines. One of the byproducts of casting processes is process scrap which amounts to about 40 to 60% of the total weight of a casting. The process scrap incorporates all the elements of gating systems and fault castings. Proper management of the process scrap is one of the necessities in term of economic and environmental aspects. Most foundries use the process scrap, which involves adding it to a melting furnace, in a haphazard way, without any control of its content in the melt. It can lead to many disadvantageous effects, e.g. the formation of a hard buildup at the bottom of the crucible, which in time makes casting impossible due to the loss of the alloy rheological properties. The research was undertaken to determine the effect of an addition of the process scrap on the mechanical properties of AZ91 and AM50 alloys. It has been ascertained that the addition of a specific amount of process scrap to the melt increases the mechanical properties of the elements cast from AZ91 and AM50 alloys. The increase in the mechanical properties is caused mainly by compounds which can work as nuclei of crystallization and are introduced into the scrap from lubricants and anti-adhesive agents. Furthermore carbon, which was detected in the process scrap by means of SEM examination, is a potent grain modifier in Mg alloys [1-3]. The optimal addition of the process scrap to the melt was determined based on the statistical analysis of the results of studies of the effect of different process scrap additions on the mean grain size and mechanical properties of the cast parts.

Casting

This chapter covers the practices and procedures used for shape casting metals and alloys. It begins with a review of the factors that influence solidification and contribute to the formation of casting defects. It then describes basic melting methods, including induction, cupola, crucible, and vacuum melting, and common casting techniques such as sand casting, plaster and shell casting, evaporative pattern casting, investment casting, permanent mold casting, cold and hot chamber die casting, squeeze casting, semisolid metal processing, and centrifugal casting.

Influence of Casting Process Parameters on Surface Roughness in Hot-Chamber Die Casting of AZ91D

Cast magnesium AZ91D, used for cases, covers and housings, for consumer electronics faces increased requirements on aesthetically pleasing surfaces. The casting conditions have strong effect on as-cast surface roughness for thin-walled castings. This is currently not well understood. In the current study surface roughness was measured parallel and perpendicular to the filling direction and on both sides on straight flat thin speci¬men. The parameters studied were First and Second phase injection speed, Cooling time, and Melt temperature. The Fix and Moving side die tempera¬tures were varied, with the fix side was kept hotter. A D-Optimal experimental design was used resulting in 31 different settings. The re¬sults showed that roughness was decreased by mini¬mizing the temperature difference between the two die halves, increasing cooling time and first phase injection speed. Increasing the second phase injection speed increased roughness.