When it comes to vacuum impregnation, it’s essential to ensure that the parts being impregnated are dry beforehand. This is because any surface impurities can interfere with the impregnation process, leading to subpar results.
If any residual fluids or debris are on the parts prior to impregnation, then the following problems may occur.
Electronics play a crucial role in electric vehicles (EVs). In 2000 automobile electronics were responsible for 18 percent of the cost of a car. Twenty years later, electronics accounted for 40 percent of a car’s cost. The use of electronics will continue to meet fuel efficiency, safety regulations, and consumer standards. However, while the use of electronics will grow, manufacturers must ensure their parts’ quality, safety, and their bottom line’s integrity.
Recent decades have seen a surge in the use of aluminum castings in car manufacturing. Aluminum has been a critical material in car manufacturing since the beginning. The first sports car featuring an aluminum body was unveiled at the Berlin International Motor Show in 1899. Carl Benz developed the first engine with aluminum parts two years later. Since then, aluminum has become the leading material used in various components and car models. Aluminum use now ranges from mass-market to luxury vehicles.
Manufacturers are constantly faced with either scrapping castings that leak or sealing the castings through vacuum impregnation. Some may perceive vacuum impregnation as a non-value added cost and assume it is less expensive to scrap die castings that leak. In this simplified yet real-world example, we will review the costs of die casting scrap compared to vacuum impregnation.
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The use of electronics in automobiles has made cars faster, safer, and more reliable. Electronics have become so prevalent that they’re practically a commodity in the same way that aluminum and steel are. As this trend continues, manufacturers need solutions that address the leak paths that occur naturally in the manufacture of these components.
Die casting is a metal casting process that injects molten metal through high pressure into a die. It is an economical process that can manufacture a high volume of parts. While die castings have a good surface finish and are dimensionally accurate, porosity inside the part is inevitable.
This blog will define die casting porosity, problems porosity causes, and how vacuum impregnation seals die casting porosity.
Automotive manufacturers realize that being environmentally responsible and profitable are not mutually exclusive. Being environmentally responsible can achieve better growth, cost savings, improve brand recognition, and increase profitability. The environmental impact of the responsible use of resources is beneficial to everyone, and automotive manufacturers play a leading role.
In some die casting applications, components must also be pressure-tight to hold pressurized fluid or gases. Companies use vacuum impregnation to meet these requirements by sealing the internal leak paths caused by interconnected porosity.
Misconceptions and lack of information about the vacuum impregnation process can hinder its implementation, which may increase unforeseen costs and negatively impact part quality. This piece demystifies vacuum impregnation by correcting three common myths.
Myth: Vacuum Impregnation is a CoatingFact: The process occurs subsurface, with no residual sealant remaining on the part’s surfaces, machine features, blind holes, and taps. Only the sealant drawn into the leak path by the force of the vacuum and pressure remains in the casting.
Myth: Vacuum Impregnation Causes Dimensional Changes to CastingsFact: Vacuum impregnation does not change the casting’s dimensions, thus allowing engineers the freedom to design and make parts to the net shapes. Since the vacuum impregnation process occurs subsurface, an engineer does not need to incorporate dimensional allowance.
Myth: Vacuum Impregnation is a Cork or PlugFact: Vacuum impregnation seals porosity deep within the leak path; it is not a cork or plug. In the case of visible or open porosity, low viscosity sealants will most likely be washed out of pits or holes. Thus, a casting with surface porosity or blemishes before the process will exhibit the same surface porosity and blemishes after the process. However, the leak path below the part’s surface is fully sealed.
In Summary A clear understanding of how vacuum impregnation works can help companies maximize their production results. As the preferred method to prevent fluids or gases from leaking under pressure, the vacuum impregnation process seals casting porosity that forms during manufacturing. When done properly, the casting will function so that fluids or gasses will flow only where needed while physical characteristics, simply stated, will not be different in any manner. Vacuum impregnation helps manufacturers decrease the rate of scrapped parts, increase productivity, and ultimately increase their profitability.
In some die casting applications, components must also be pressure-tight to hold pressurized fluid or gases. Companies use vacuum impregnation to meet these requirements by sealing the internal leak paths without impacting any other features of the casting. A commonly asked question is in addition to leak paths, can vacuum impregnation seal cracks?
The goal of a foundry is to produce high quality die castings that meet or exceed the customer’s specifications at a competitive cost. In some die casting cases, those specifications require that the part must hold pressurized fluid or gasses. Companies use vacuum impregnation when the part must hold fluids or gasses under pressure. A common question asked about vacuum impregnation is “When Should I Impregnate a Casting?” This video addresses this question by answering if vacuum impregnation should be done before or after machining and finishing.
Hey, everyone. Welcome to “Casting Call” with Johnny Impreg. This is a premiere episode of a video blog series where we hope to answer all your compelling questions of everything impregnation. We’re going to start with the question I think I hear most often from folks is, “When should I impregnate a casting?”
Now, spoiler alert, I’m going to give you the answer now in case you’re short on time. But you want to do the impregnation after machining and prior to any kind of finishing like plating or painting.
Now, here’s why. Let’s consider the three different types of porosity you see in a raw casting—blind porosity, through porosity, wall to wall, and fully enclosed. If you impregnate a casting in this condition, you’ll get sealant in the blind. You’ll get it here, but you won’t get any sealant in this area. That becomes important when you do the machining, because when you machined from here, you’re going to have a leak path.
Now, if you do the impregnation after machining, you’ll still fill this and now you’ll fill this leak path as well. The reason you want to do it prior to finishing is you want to fill up all the porosity before you do the plating or painting. Otherwise, you could end up with out gassing or other blemishes that really don’t look so nice.
Let’s look at a real-world example on a cylinder block. Now, in this region here, we had a case where there was blind porosity going from here into the casting. It didn’t cause a problem until this machining cut was made. We have some other areas where we had enclosed porosity that was connected through two different machining passes. So, this is a real-world example of why you should do impregnation after machining.
So, I hope this little tutorial helped you. If you have any questions, please feel free to leave comments below and hit me up on WhatsApp or LinkedIn.
