Poor-quality binder, inadequate mixing of the raw materials used in making sand cores or even incorrect storage may affect the quality of the cores and therefore, indirectly, that of the castings.
By means of the COGAS®Al Test Unit, it is possible to detect inferior-quality sand cores, thus making it possible to reject them before they are used in the production process. The number of reject castings caused by heavy condensation or sand cores with high gas contents can therefore be substantially reduced.
For the production of good pore-free castings, knowledge of the creation of gases by the core materials is essential so that venting systems and sand-binder mixtures can be selected accordingly. The COGAS®Al Test Unit makes it possible to simulate the casting process using a test core measuring approx. 23x23x30 mm which is completely immersed in an aluminium melt. The test core is heated by the melt and the gas created by the decomposition of the binder is caught, thereby making it possible to measure the amount of gas being generated as decomposition progresses. At the same time the emitted condensation can be trapped and subsequently weighed and analysed. For standard tests, we offer a test specimen with a standard geometry, but pieces from actual production cores can also be tested for production control. In this way it is possible to determine the effect sand cores have on the production process, especially with regard to type and quantity of binder, mixture quality, shot parameters and storage conditions. Once the best production parameters have been defined, this reliable production-related test method can be used to detect and correct any possible deviations, thus guaranteeing effective process control.