Optimization of chemical bonded sand moulds for big size cast components. Reduction of manufacturing costs

The production of big size cast components to accomplish the demanding market requirements requires advanced design concepts, a proper metallurgical quality, as well as a stable and robust process control. The optimization of these three key factors will allow to reach the highest casting quality standards, along with the corresponding manufacturing cost reductions.
The moulds produced by chemical binding systems (phenolic, furan, silicate, …) usually include different controls of the mix (sand-resin-catalyst), although the obtained information is exclusively referred to the properties of the sand mix potential (sand test bar) and not to the real mould characteristics, which in common practice are barely evaluated. The fact that the mix presents adequate characteristics does not mean that the properties of the mould will meet the requirements of the part to be manufactured.
It must be taken into consideration that the final characteristics of the mould depend as well on additional factors beyond the mix itself. Indeed, the geometry of the casting to be produced, the ramming conditions (vibration and compression), the curing time, the amount and quality of resin and catalyst used, the bench life, the box conditions, … etc, are some of them.
In order to give an appropriate answer to the above mentioned deficiencies, we have developed a new control test method for industrial application, which is able to evaluate the mechanical properties of the moulding system (potential of the binding system) and the own characteristics of the mould. Based on these test results important improvements can be achieved (product quality improvements as well as manufacturing cost reductions). It has been repeatedly proved that a correct mould stability can allow to develop process optimization strategies in order to reach significant competitive advantages (minimization of risers and chills, casting internal soundness improvements, costs reduction in fettling operations, … etc.).
This technical paper presents the results of the different tests performed on chemical bonded sand moulds at laboratory and industrial scale, with further evaluations on the final quality of the castings produced and manufacturing cost reductions.