Moulding techniques

Moulding, that is, creating the mould (see also section “1.2.2 – Preparation of moulds and cores”), can be done in different ways:

Manual moulding

In the case of large castings and/or castings to be produced in small series, the mould is obtained using simple manual tools to tamp the sand and binders around the half-models (normally in wood or plastic) positioned inside a flask. Manual moulding is generally suitable for the production of medium-large moulds; the final result is naturally highly dependent on the operator’s experience. Precisely for this reason, this type of moulding presents certain issues in terms of its repeatability. 

Mechanical moulding

For castings in contained sizes to be produced in relatively large series, sand and binders are pressed with various mechanical devices around semi-models (typically in metal). The pressing devices are rather simple to use and do not require particularly qualified or expert personnel. The limits of this technology are normally size-related. The geometric characteristics of the possible moulds are in fact bound to the dimensions of the work area of the pressing device.

Automated moulding

The moulds are made using an automated system (called DISAMATIC®), which very rapidly produces boxless moulds (moulds without flask, self-consistent) by loading sand and binders into a pressing chamber. The system also allows the automatic insertion of cores, even with very complex geometries, inside the boxless moulds. This technique is the ideal solution for achieving high productivity and is therefore suitable for large series production. Only a few seconds elapse between the preparation of the boxless mould and the casting, thus avoiding any problems associated with storing the boxless moulds themselves. Clearly, this type of system requires a particularly high investment due to both the base-plant and the numerous supporting robotic devices. These costs can only be amortised against the production of very large series of castings.

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