Copper castings are prone to cracking during the processing, which not only affects product quality but also increases production costs. To avoid the occurrence of cracks, comprehensive control is needed from multiple aspects such as material selection, casting process, heat treatment, and processing parameters. The following will explore in detail how to avoid cracks during the processing of copper castings from multiple perspectives.

1、 Material selection

Composition control of copper alloy

The composition of copper alloy has a significant impact on the properties of castings. Copper alloys with different compositions have different coefficients of thermal expansion, thermal conductivity, and mechanical properties. Choosing the appropriate copper alloy can reduce the occurrence of cracks. For example, adding appropriate amounts of zinc, tin, aluminum and other elements can improve the strength and toughness of copper alloys, and reduce the tendency to crack.

Impurity content control

Impurities in copper alloys, such as sulfur, phosphorus, oxygen, etc., can significantly reduce the toughness and strength of the material, increasing the risk of cracking. Therefore, the impurity content of raw materials should be strictly controlled before casting, and refining treatment should be carried out if necessary.

2、 Casting process

mould design

Reasonable mold design can effectively reduce stress concentration and decrease the occurrence of cracks. Molds should avoid stress concentration areas such as sharp corners and edges as much as possible, and use rounded transitions. At the same time, the cooling system of the mold should be designed reasonably to ensure uniform cooling of all parts of the casting.

Pouring temperature control

Excessive or insufficient pouring temperature can increase the risk of cracking. Excessive pouring temperature can cause significant thermal stress during the cooling process of castings, while excessively low pouring temperature may lead to defects such as cold shuts and shrinkage cavities inside the castings. Therefore, the appropriate pouring temperature should be selected based on the specific material and casting shape.

Cooling rate control

Excessive cooling speed can cause significant thermal stress inside the casting, increasing the risk of cracking. Therefore, appropriate cooling measures should be taken, such as using insulation materials, adjusting the temperature and flow rate of the cooling medium, etc., to ensure uniform cooling of the castings.

3、 Heat treatment

Annealing treatment

Annealing treatment can effectively eliminate residual stresses inside castings, improve material toughness and plasticity, and reduce the risk of cracking. The annealing temperature and time should be reasonably selected according to the specific material and casting shape.

aging treatment

For certain copper alloys, aging treatment can improve the strength and hardness of the material while reducing residual stress. The temperature and time for aging treatment should be reasonably selected according to the specific material and casting shape.

4、 Processing parameters

Cutting speed and feed rate

In the process of mechanical processing, cutting speed and feed rate have a significant impact on the surface quality and internal stress of castings. Excessive cutting speed and feed rate can cause significant cutting stress on the surface of castings, increasing the risk of cracking. Therefore, the appropriate cutting speed and feed rate should be selected based on specific materials and processing requirements.

tool selection

The material and geometric shape of the cutting tool have a significant impact on the cutting force and cutting heat during the machining process. Choosing the appropriate tool can reduce cutting force and cutting heat, and lower the risk of cracking. For example, using sharp cutting tools and appropriate tool angles can reduce cutting stress.

Cooling lubrication

During the machining process, using appropriate cooling and lubricating fluids can effectively reduce cutting temperature, minimize cutting stress, and lower the risk of cracking. The selection of cooling lubricant should be reasonably based on specific materials and processing requirements.

5、 Other measures

stress release

During the processing, residual stresses may be generated inside the casting. Appropriate stress relief treatments (such as vibration aging, natural aging, etc.) can effectively reduce residual stress and minimize the risk of cracking.

quality control

During the processing, strict quality control should be implemented to promptly detect and address potential crack defects. For example, non-destructive testing (such as ultrasonic testing, X-ray testing, etc.) can promptly detect internal crack defects in castings and take corresponding treatment measures.

Process optimization

Through process optimization, the risk of cracking can be effectively reduced. For example, adopting advanced casting processes such as low-pressure casting, centrifugal casting, etc. can improve the quality of castings and reduce the occurrence of cracks.

The generation of cracks during the processing of copper castings is a complex problem that involves multiple aspects such as material selection, casting technology, heat treatment, and processing parameters. By comprehensively controlling these factors, the risk of cracking can be effectively reduced, and the quality and reliability of copper castings can be improved. In actual production, corresponding measures should be taken according to specific materials and processing requirements to ensure the quality of castings.