Mould and core coatings are important foundry auxiliaries and are often underestimated as the key to better castings. Coatings represent a special component in shaping. They have a very great influence on the metallurgical properties of the surfaces, on surface defects and on the appearance of the castings.
Mould and core coatings are also important parting agents which ensure clean and beautiful surfaces of the castings. Their effect of separation avoid surface defects of the castings. They prevent the penetration of metal into the moulding material and thus avoid the burning of the sand on the casting surfaces. Mould veining, which can occur as a result of expansion defects of the sand, are prevented. Furthermore, they can influence the metallurgical properties of the surfaces of castings by using them as a barrier or as metallurgically effective coatings.
The composition of modern coatings is very diverse. They are suspensions of fire-resistant fillers that have to meet various requirements. The refractory fillers form the most important component in terms of fire resistance and compatibility with the casting material and the moulding material. The binders used must be matched to room and casting temperature. The rheological instruments used determine the application process, whether through dipping, flooding or spraying.