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.
Simply stated, porosity is any void or hole found within the casting. Porosity is inherent in die casting manufacturing. While economical, the high speed process of injecting molten metal into a die inherently creates porosity. The two most common types of casting porosity types are: gas porosity and shrinkage porosity.
Fully enclosed porosity is not a problem unless secondary machining uncovers this porosity. Machining can break fully enclosed porosity, which will then turn it to either Blind or Through porosity.
Causes of Porosity in Die Casting
- The design of the mold and cast parts
- The purity of the metal or alloy being used
- Pressure and shot speed of the machines
- Shrinkage of the material wall thickness
- Too much lubricant in the die
- Sharp corners in the mold
- Low metal temperatures
- Air trapped in the metal
The most common way to check for porosity is an X-ray of the material, using computerized tomography or by cutting and polishing a section and then analyzing it under a microscope.
How to Fix Die Casting Porosity?
Vacuum impregnation is a method that seals the casting resulting from porosity. The impregnating material is introduced into the voids within the wall thickness of the casting through vacuum and/or pressure methods. This method is a cost effective and permanent solution to casting porosity. There is no limit to the size of castings which can be impregnated.
A key characteristic of a successful impregnation process is that it seals the component without changing any of its assembly, functional or physical characteristics. Assembly characteristics include performance of tapped holes; the integrity of mating and sealing surfaces; and the elimination of residual contamination. Functional characteristics include the ability for fluids or gasses to flow only where needed in order to enhance in-service performance of the component’s design while physical characteristics, simply stated, are the component must not appear to be different in any manner.
If you’re concerned about the porosity of your casting, we recommend you contact us directly to learn more.
JINGXIN is your ideal partner & factory in aluminum & zinc die casting
JINGXIN® is a full-service supplier of quality products in the aluminum die casting, zinc die casting, post process CNC machining, finish treatment in house; We are an ISO 9001:2008 and IATF 16949 certified factory in China. With our 15+ years skilled R&D Team support, We have successfully finished over 2000+ cases to our customers over the world. We have been serving customers in various fields, which include new energy automobile, LED lighting, industrial automation, communication engineering products and more.
Die Casting Workshop
With 150-1600T high precision die casting machines, to meet all die casting parts’ dimension requirements. JINGXIN® provides high pressure die casting, and a range of post process custom manufacturing such as CNC milling, CNC turning, finish treatment. parts assembly ,. etc . the integrated services required to be your complete global manufacturing resource.
Quality Assurance & Control
ISO certificated and IATF 16949 Certification. our quality policy is “Integrity Centered, Customer First, Quality Priority and Continuous Improvement”. Every steps are under ISO such as mold design, mold making, die casting, post machining fabrication.