for the even application of alcohol-based and water-based coatings by means of flooding or dipping
A coating is made up of the following components:
Today, only water or alcohol is used as the liquid carrier.
The binders must develop sufficient binding forces both at room temperatures and at high temperatures.
The suspension substances should stabilize the viscosity of the liquid carrier or, ideally, increase it, so that the refractories are kept in suspension.
In addition to the correct selection of refractory materials for the coating, the setting of the layer thickness has a decisive influence on the casting result. With the thin layer thicknesses that are common today and are also necessary, casting defects can be effectively avoided despite metallostatic pressures of several meters and casting temperatures of 1600 ° C.
Coatings are applied in liquid or paste form. This can be done by painting, spraying, flooding, or dipping. For larger molds, the most economical way is to flood the molds. This shows the following advantages:
AAGM now offers an automated solution (Fig. 1, AAGM Aalener Gießereimaschinen GmbH) in order to avoid the manual viscosity determination of the size, which is still carried out and the subsequent manual correction of the viscosity.
In the case of the flooding and dipping station newly developed in cooperation with the company Mezger / Kallnach (Switzerland), an agitator is installed in the delivery container for the coating, thus keeping the base size homogeneous. A control doses the required amount of coating into the mixing tank of the station and calculates how much liquid carrier or paste-like coating has to be added in order to achieve the desired viscosity. An integrated stirrer reliably mixes the components without having a negative impact on the properties of the size due to intensive shear forces.
A smart pump system (Fig. 2, AAGM Aalener Gießereimaschinen GmbH) conveys the finished coating to the flood basin, is adapted to the respective customer requirements and has an integrated plunge pool (Fig. 3, AAGM Aalener Gießereimaschinen GmbH).
The flood lance is activated via a push button to coat the molds. The draining size is collected in the collecting basin, the coarse parts being retained by a freely accessible sieve ring before the size is pumped back into the mixing tank. To protect the membrane pump, a generously dimensioned prefilter is built in, which holds back grains larger than 1mm.
The control of the system monitors the viscosity of the coating at adjustable intervals. In the first step, the supply quantity is checked and corrected depending on the temperature. In the second step, the viscosity is adjusted by adding liquid carrier. After stirring, the coating is available again in the set quality.
In order to keep the temperature in the mixing container at a constant temperature, it can optionally be equipped with a heating jacket.
The system thus offers continuous, user-independent monitoring of the coating quality.