Customers often ask us how sealant is removed from machined features, like tapped holes. Customers assume that the holes are masked, but that is far from the truth. In this blog, we will discuss what in the vacuum impregnation process enables a casting to be properly sealed without excess cured sealant in unwanted areas (sealant contamination).
Vacuum impregnation is commonly used as a preventative measure to keep castings pressure tight. But when use on powdered metal parts, vacuum impregnation is used as a value added process. In this blog, we will answer the common questions we receive about impregnating powdered metal parts and explain why it is a value added process.
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Paragraphs 4.4.2 and 4.4.3 of MIL-STD 276A requires a minimum vacuum of 29 inches of mercury. This requirement creates a dilemma for people performing MIL-STD 276A at elevations above sea level. The reason: this scale is measuring vacuum relative to sea level and using a gauge with this scale at elevations other than sea level requires a correction. To understand this let's look at the operation of the gauge.
There are three types of vacuum impregnation processes:
Dry Vacuum Pressure (DVP) is the most commonly used process in Godfrey & Wing equipment. To better understand the DVP process, this blog will discuss the process step by step, and its advantages. The following example illustrates engine blocks being impregnated in a traditional batch system.
Water, as we all learned in basic chemistry, exhibits a unique phenomenon: as it solidifies, it expands. For other liquids in our physical world, solidification results in just the opposite: shrinkage.
Electronic connectors can be found everywhere, from automobiles to airplanes. Consequently, the effects of their failure range from the inconvenient to the tragic. The number of such failures can be reduced by better methods of sealing connectors against the conditions that lead to corrosion.
Customers often ask us if vacuum impregnation should be done to castings before or after machining. The following visual aids will answer this question.
Ever since metal casting was first discovered, casting porosity, an area of sponge-like internal structure in an otherwise sound metal part, has been a problem. Porous castings may be caused by internal shrinkage, gas cavitation, oxide films, inclusions and combinations thereof. It can be found in virtually any type of metal casting or part, and is a particular problem in castings made from aluminum, zinc, bronze, iron, magnesium, and other alloys. Porosity is always present in powdered or sintered metal parts because of their structural nature.