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What is Porosity and How it Affects Pressure Die Casting?

by Nice Rapid | Mar 26,2021 | Pressure Die Casting

If you go to the human definition of "pore", you'll find out its millions of tiny microscopic holes in your skin that allow sweat to get out. When it comes to pressure die casting, a pore it's a little hole in an otherwise solid metal cast. They are usually really small, but if we don't notice them, they can create a fair amount of issues in our finished products. Pores happen for two main reasons:

  • A solid mold is over shrinking the parts after they are finished
  • Gas is leaking inside the mold 

Here is how we can deal with these issues: 

Solidified Shrinkage

The injection of materials into the mold and the cooling process means that we'll have to deal with shrinkage rather sooner than later. The metal's cooling rate is something pretty significant that needs to be accounted for before starting a production cycle. The way the mold is tooled has a major impact on this, meaning: if the mold has been badly crafted, the product will come off wrong.

The most efficient way to deal with this issue is to do a lot with geometrics, math, and the proper handling of modeling software. The first portion of the mold, the one that gets in contact with the noose it's where pores are created. If the molten metal gets stuck in this section, not only will you face a whole batch of products poorly made. You will also break your die casting machine.

The best solution for this issue it's getting the planning stage right and triple-checked before getting started. The time you lose on prep work, it's time you win when your production cycles go according to plan.

die casting porosity

Gas Leaks

Gas pockets happen when you are working with highly malleable metals such as aluminum or zinc. They call for their fair share of hydrogen in the process, and your die casting machine it's not calibrated correctly, you will get a lot of porosity in your finished products. Unfortunately, this is not the only source of the problem when it comes to gas.

If your mold has too many notches, you will have to deal with air traps that can create imperfections or even make the ejection process problematic, hence the constant recommendation on behalf of technicians to trim down your products' complexity. A poorly evacuated mold is a significant cause for concern since you can get finished products missing whole sections on it.

As challenging as this sounds, the hard fact is that you cannot get rid of porosity on pressure die casting manufacturing. The issue usually accounts for presence in at least 4.5% of the surface of your product. But you can do everything on your end to make sure it's barely noticeable.

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