| Popis: |
The production of high pressure die casts also brings difficulties regarding the processing of the waste material. It is mainly formed by runners, overflows and other foundry supplements used and, in the case of machines using the cold chamber, also the remainder from this chamber. As this material is often returned to the production process, we refer to it as return material. In the production process, it is therefore essential to deal with the proportion issue of return material against primary material that can be added to the melt to maintain the required cast properties. The submitted article monitors the quality properties of the alloy, selected mechanical properties of casts and porosity depending on the proportion of the return material in the melt. At the same time, the material savings are evaluated with regards to the amount of waste and the economic burden of the foundries. To monitor the above-mentioned factors, series of casts were produced from the seven melting process variants with a variable ratio of return to the primary material. The proportion ratio of return material in the primary alloy was adjusted from 100% of the primary alloy to 100% of the return material in the melting process. It has been proven that with the increasing proportion of the return material, the chemical composition of the melt changes, the mechanical properties of the alloy decrease and the porosity of the casts increases. Based on the results of the tests and analyzes, the optimal ratio of return and primary material in the melting process has been determined. Considering the prescribed quality of the alloy and mechanical properties, concerning the economic indicator of the savings, the ratio is set at 70:30 [%] in favor of the primary material. |
