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

Date：2023-01-05 16:27:39 Views：901

Castings are metal shaped objects obtained by various casting methods, that is, smelting good liquid metal. By using casting, injection, suction or spray casting methods in other pre prepared molds, and cooling through subsequent treatment after grinding, the metal castings obtained will form a certain shape, size and product performance. Due to the complexity of the casting process, the lax control of raw materials, the imperfect production process, and the unreasonable mold design, various defects will occur in the production and operation of castings. Common defects include gaps, bubbles/pores, looseness and mixing. In order to ensure the quality and cost saving of castings, it is necessary to carry out defect detection at the early stage of the production process. Because the inspection results are intuitive, the inspection efficiency is high, and the application conditions are extensive, X-ray nondestructive testing has become the preferred method for casting defect detection.

The main defects of common castings are as follows:

1. Porosity: the cause of affecting the porosity is that there is too much water in the molding material or a large amount of gas generating material; The permeability of molding sand and core sand is poor; The pouring speed is too fast.

2. Sand hole: sand hole is caused by insufficient strength of molding sand; The compactness of molding sand is insufficient; The casting speed is too fast, etc

3. Shrinkage cavity: the cause of shrinkage cavity is poor feeding of casting during solidification.

4. Sand sticking: The reason for sand sticking is that the refractory of molding sand is poor or the temperature of the pouring system is too high.

5. Cracks: the wall thickness of the cracked castings is caused by large differences; Improper setting of the gating system, etc.

X-ray is a kind of non-destructive testing, which has the characteristics of non-destructive testing: it does not damage the detection target; 100% inspection can be achieved; We can find and evaluate defects, evaluate the quality of the main body, evaluate the causes of defects, judge the law of development, promote relevant departments to improve the production process and product quality, and frequently check core components to ensure safe operation and avoid accidents.

At the same time, the biggest difference between X and other NDT methods is that X intuitively conducts radiographic inspection through images, which is not difficult to find defects. The inexperienced subjective judgment greatly improves the accuracy of defect detection. The X-ray nondestructive testing system can identify the location and size of defects and store data for data traceability. With the acceleration of the transformation and upgrading of the manufacturing industry, enterprises have higher and higher requirements for quality. X-ray industrial testing equipment is widely used in industrial production and internal defect detection of industrial parts. In the die casting industry, X-ray inspection can detect cracks, pores, shrinkage and other defects of castings, ensure the quality of products before shipment, provide data reference for enterprises, and improve the production process.

X-rays have strong penetrating power, and can obtain information about internal objects through the surface of objects without being affected by magnetic field. According to the ray attenuation law and distribution, the thickness and internal defects of the object can be reflected through the image through computer information processing and image reconstruction technology by using the X-ray emitted by the radiation source to pass through the measured object. Therefore, X-ray nondestructive testing technology is one of the main industrial nondestructive testing technologies, and also an important method for analyzing commodity defects and quality evaluation.

The above is related to the X-ray non-destructive testing of internal defects of castings compiled by the trauma core testing team. I hope it will be helpful to you. Chuangxin Testing is a professional testing agency for electronic components. At present, it mainly provides integrated circuit testing services such as capacitance, resistance, connector, MCU, CPLD, FPGA, DSP, etc. Specializing in electronic component function testing, electronic component incoming appearance testing, electronic component dissection testing, acetone testing, electronic component X-ray scanning testing, ROHS component analysis testing. Welcome to call, we will serve you wholeheartedly!