What are the internal defects of die castings detected by X-ray?

- Dec 10, 2018 -

Foundry is one of the basic processes in modern mechanical manufacturing industry. It has the advantages of low cost, one-time forming and large parts with complex structure. It is widely used in automobile parts, mechanical manufacturing, electronics, medical devices, clocks and watches, hardware products, aerospace and other industrial production fields.           

 Foundry is an important basic industry of machinery industry. Nowadays, with the rapid development of information, improving the production efficiency and quality of foundry will be the subject that foundry workers must face. Traditionally, the high rejection rate of castings is a common problem of various casting methods in the industry. How to better control the quality of castings and improve the casting process is particularly important.           

Because of the complexity of casting process, there are many factors affecting the quality of castings. Lack of strict control of raw materials, unreasonable process plan, unreasonable die structure design and improper production operation will lead to various defects in castings, such as inclusions, bubbles/blowhole, looseness and cracks.          

 Common Defect 1: Crack           

The main reason is that the unreasonable structure design and fabrication process are not up to the standard. There are two main types of cracks: casting crack and heat treatment crack.                       

Common Defect 2: Bubble/Blowhole           

The main reason is that the casting is not ventilated properly during the casting process, which is caused by air or impurities. The bubble/pore on the workpiece surface can be found by sandblasting treatment, and the bubble/pore in the workpiece can be detected by X-ray fluoroscopy.           

Common Defect 3: Porosity           

Because of unreasonable design structure, casting looseness usually occurs at the thick and thin junction of the wall near the inner runner, the thick and large part of the riser root and the thin wall with large plane.          

Common Defect 4: Inclusion           

The main reason is that the burden is not clean or the slag inclusion is improperly mixed in the operation. It is mostly distributed on the upper surface of aluminium castings and at the corner where the mould is not ventilated.