The Maldaner Italia trial
Impregnation does not change the dimensional and mechanical characteristics. The pieces must not be retouched.
The Maldaner Italia process consists of 6 steps:
Dry vacuum – A vacuum of 5 -3 bars is specially created to extract the air from porosities.
Wet vacuum – While the vacuum of 5 -3 is maintained, the resin is transferred inside the autoclave to dip the pieces into it. The resin penetrates the porosities by depression.
Pressure – Pressurization of the autoclave for optimal penetration. Return of the resin to the tank.
Dripping – By rotating the basket at intermediate stops for impregnation, excess resin is recovered.
Washing, rinsing – A first phase washing and a second phase rinsing, in a solution of water with specific detergents at thermoregulated temperature, allow to eliminate the resin residues deposited on the surface of the pieces. In the case of blind holes or small diameter threaded holes, the working procedure involves a specific washing.
Polymerization – The resin found in the porosities remains liquid at room temperature, but polymerizes at 90 ° C and becomes a solid, elastic and inert body. After cooling, the parts can be tested or used directly.
Drying – The jets are dried from excess humidity by means of a special drying oven (optional).
The advantages of impregnation
Most foundry pieces are not impermeable to gases and liquids.
The cause of this defect is to be found in the metal casting method. Cracks, cavities, porosity, etc. are formed at this stage of processing.
Such manufacturing defects are rarely visible to the naked eye. Impregnation is the only process capable of definitively solving the waterproofing problems of the pieces.
Particularly complex parts, strict quality requirements and specific cost-related requirements have made impregnation the ideal answer to all foundry problems.
Impregnation allows to obtain a waterproofing equal to 10 -6 bar to helium, resisting very high pressures (800 bar). In many cases impregnation is foreseen by the processes.
The three porosity classes:
The internal porosities – Without consequences but likely to become passers-by during processing.
Surface porosities – They can cause aesthetic defects (oozing, oxidation, degassing).
The passing porosities – They are among the most serious as they allow the infiltration of liquids or gases.
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