Evaluation of methods for metal cleanliness assessment in die casting

Faced with higher quality requirements, many die casters need to assess and monitor the cleanliness of the metals used in their operations. While several assessment methods are available, only some are considered to be feasible for die casting. This paper reports a preliminary study that evaluated three feasible assessment methods: K-Mold, mechanical testing, and porous disc filtration apparatus (PoDFA). Results indicate that each method may be used for different purposes and is suitable for different applications. The K-Mold is a quick and simple method that provides information on macro-scale inclusions. It is a good quality control tool for die casters that do not have high requirements for mechanical properties. Mechanical testing can provide both qualitative and quantitative information of the metal cleanliness. The results suggest that elongation is a more appropriate parameter. Modification of the mold to minimize shrinkage porosity is recommended. PoDFA is a good tool for identifying the major types of inclusions present in the molten metal. Modifications of the testing procedure are needed if it is to be used with different sample sizes.