What is porosity?
Ever since metal casting was first established, casting porosity (an area of sponge-like internal structure in an otherwise sound metal part) has been a problem. Even with careful production techniques, castings that are made of iron, copper, aluminium and magnesium etc are often porous and therefore unsuitable for their intended use, e.g. as motor parts, heat exchangers, pump casings, filter parts or valves. Additionally, following machining porosity may be exposed on cast parts that were originally pressure tight causing them to start leaking.
Why does porosity appear?
Porosity may appear because the outer contours solidify first when cooling at the end of the casting process. When further cooling of the castings takes place, the metal can shrink, and porosity can form inside the castings. Despite advances in processing, sometimes porosity cannot always be avoided. Other factors like melting temperature, alloy composition and mould design can also influence the quality of the casting.
What’s the Solution?
Impregnation. Expensive porous castings do not need to be scrapped, and some products can even be enhanced with the metal impregnation process. ISL enhance quality and reduce scrap in ferrousand non-ferrouscast metal parts.
It is also far more cost effective to impregnate porous castings than to scrap them. Impregnation allows the manufacturer to save time, money, energy and ensure quality by salvaging parts which would otherwise have to be rejected. By reducing the number of ruined parts caused by porosity and the resulting leakage, impregnation also helps to minimise waste.
Due to the proven effectiveness and economies of impregnation, many engineers now specify its use for all types of metal parts that must contain liquids or gases under pressure. It is now common for impregnation processes to be incorporated directly into production schedules to ensure quality, rather than to be used strictly to recover parts.
If you have 1 or 1,000 pieces, new or used, large or small, for recovery or sub surface quality enhancement, ISL can help.
Our purpose-built facility allows us to turn ordinary castings into high-pressure, sub-surface sealed, fit for purpose parts, for use in any number of applications. We provide vacuum impregnation of castings to a vast array of industries including aerospace, automotive, oil and gas and marine.
Do you suffer from leaking or porous castings? Do you want to recover your castings and seal them for life? … Call the casting impregnation experts.