How to Check Porosity in Castings

During the routine inspection at our CEX Casting, we met a very interesting issue: how to find out the hidden porosities in the aluminum alloy castings.

It seems a small issue, but it may cause the whole batch of the castings to be rejected, which shows the importance of the quality control in our industry.


To effectively check for porosity in castings, you need to use non-destructive testing (NDT) methods like X-ray or ultrasonic testing.

These methods let you find the porosity inside without breaking the casting.

This way you can make sure your stuff works and meets quality standards.


It is of great importance to guarantee the structural integrity and mechanical performance of castings, especially in some critical applications like automotive industry where safety and reliability are non-negotiable.

Porosity, also named as voids or air gaps in metal, can seriously affect these properties, which makes its detection a crucial part of manufacturing process.

What Is Porosity, and Why Is It a Problem in Castings?

Porosity in castings means there are voids or air holes in the metal during solidification.

These voids will weaken the structure of the casting and reduce its strength and durability.

In some critical applications, such as automotive and aerospace, porosity may cause the component to fail and result in serious safety problems.

How Does Porosity Affect the Mechanical Properties of Castings?

The porosity in the casting will have a significant effect on its mechanical properties, such as tensile strength, ductility and fatigue resistance.

It is easy to cause the casting to crack due to the porosity under the stress, which will lead to the premature failure of the component.

This is especially serious for industries where the components are subjected to high stresses and strains during their operation.

What Are the Main Causes of Porosity in Aluminum Alloy Castings?

Porosity in aluminum alloy castings can be attributed to several factors, including gas entrapment, shrinkage during cooling, and improper gating system design.

Gas entrapment occurs when gases are trapped within the molten metal and become enclosed as the metal solidifies.

Shrinkage porosity happens as the metal cools and solidifies, leading to a volume reduction that creates voids.

Additionally, an improperly designed gating system can contribute to turbulent flow, which promotes the formation of porosity.

How to Check Porosity in Castings?

It is always a challenge to find out the porosity in castings, especially when the voids are inside and invisible.

Non-destructive testing (NDT) methods are very important to detect these defects.

X-ray inspection is a very good way to see the inside structure and find out the voids that may affect the quality of the casting.

Ultrasonic testing is also a good method. We use high frequency sound waves to detect the defects in the material.

These methods can help us to check the quality of the casting without any damage, and to ensure the components we deliver to our clients are all in good quality.

detect porosity

What Steps Can Be Taken to Minimize Porosity in Castings?

To minimize porosity in castings, we need to do it from many aspects. Firstly, design the mold and gating system to make the molten metal flow smoothly and without turbulence.

Secondly, control the temperature and composition of the molten metal, as they have great impact on the generation of gases and shrinkage.

Thirdly, squeeze casting can be adopted to make the structure denser and more uniform.


At CEX Casting, we know the importance of minimizing porosity in aluminum alloy castings to ensure the highest levels of safety and reliability for our clients.

With the application of advanced NDT techniques and meticulous process control, we are committed to delivering components that meet the most stringent quality standards.

Our dedication to excellence in casting technology not only makes us a leader in the Chinese market, but also a trusted partner to industries worldwide.

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