How to Prevent Porosity in Die Casting Parts and What to Look for When Preventing it from Ansel Rockefeller's blog

We are all aware of the pores on our skin and the porous nature of materials such as wood, which allow intruders such as water and bacteria to enter the material and cause it to become contaminated. As a result, many chefs recommend that when cutting raw chicken, plastic cutting boards be used rather than wooden ones.

Porosity is also a major concern in die casting because it can indicate the presence of a defect in the material you're working with or in the product you've just created, which is dangerous. Good news is that porosity does not always indicate that a casting is defective and that it is necessary to make modifications to it. According to a thorough inspection, it may be found to meet all of your requirements for structural stability as well as structural integrity.

Porosity in die casting is defined as a void in the material.

Whenever small voids, holes, or pockets of air can be found inside of a metal, the porosity of the metal is referred to as the porosity of the metal.

Porous metal is typically caused by air being trapped in the metal by the die casting services machinery, resulting in gaps at the top of the die, or when a mold is filled too slowly, resulting in some solidification occurring prematurely. Another cause is when the air used to force molten metal into the mold is not completely forced out or is not able to escape through vents and overflows after the mold has been removed from the heating source.

There are a variety of factors that contribute to porosity in zinc die casting.

Machine pressure and shot speed are affected by the purity of the metal or alloy that is being used in the mold design and in the components of the casting machine.
 

  • This is due to the reduction in the thickness of the wall of the material.

  • In the die, there is an excessive amount of lubricant present.

  • In the mold, there are some sharp corners.

  • Too low metal temperatures are a problem.

  • The trapped air is suffocating the metal, which is causing it to corrode.
     


In order to determine porosity, the most common methods are to take an X-ray of the material and use computerized tomography, or to cut and polish a section of the material and examine it under a microscope to determine its porosity.



Methods of Taking Preventive Measures

The severity of porousness varies from person to person. It is acceptable on occasion, but it is preferable to keep it as low-profile as possible the majority of the time if possible.

Working collaboratively with all of your partners to develop a cost-effective aluminum alloy die casting process while also making certain that the material you're working with is of high quality and consistency is the most direct way to control for porosity. During the casting process, special attention should be paid to equipment maintenance and stability, as this can aid in maintaining an even and adequate amount of pressure throughout the casting process.

It is necessary to melt the material in a vacuum or in an environment containing low-solubility gases, such as argon, in order to avoid gas porosity, which is the formation of air bubbles within a casting as it cools. As a result of the ability of liquids to naturally hold in dissolved gas, porosity is created in the liquids. When a melted material comes into contact with another gas, the two gases react and pull each other out of the liquid, which in some cases can solve the problem and prevent further melting.

If oxide formation is the source of the porosity in your materials, you will benefit from having them properly degassed after melting and filtered before using the metal to make the casting.

When issues arise during the cooling process, hot tears and hot spots can occur. These are metallurgical defects that can occur as a result. It will be necessary to ensure that your casting is properly cooled in the affected area of the part if this happens. You will need to modify your cooling practices if hot spots continue to exist. You can do this by increasing the amount of die spray applied or by adding more localized cooling channels to the problem area in question.


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By Ansel Rockefeller
Added Jan 10

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