For moulding with bentonite sand mixture or green sand, wooden or metal patterns are usually used. The production and processing of these models is time consuming and usually also expensive. The choice of material is often based on how many moulds we will build with the pattern. For small businesses that have small series of castings, these procedures are too time consuming, so 3D printing could be a good solution. 3D printing technologies are rapidly evolving and becoming more accessible to both personal users and smaller businesses. That's why I tried to test whether models that are printed on 3D printers can be used for moulding with bentonite sand instead of classic wooden or metal patterns. When we try to remove the pattern from the mould, it can be broken. The problem can arise due to insufficient pattern angles (sides are too vertical) due to the inappropriate properties of the sand mixture or the surface of the model. Therefore, we have developed three models with different surface quality, selected four different moistures in the range of optimum strength properties for the sand mixture with given bentonite content, and selected the models so that they have as many different casting angles as possible but they are still sufficient for casting conditions. By doing this, we checked the quality of the printer and consequently 3D printing. We also checked the importance of moisture, properties of the sand mixture, and the angles at which moulds begin to crumble. After repeated sampling of different models for different moisture content of the sand mixture, it was found that the mould is well maintained in most cases. Almost all samples, where we had errors in the mould, collapsed at the most vertical sides or at patterns that had a 3D printing errors.
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