Aluminum alloy, zinc alloy, magnesium alloy, and other nonferrous alloys with low melting points are the most common die casting alloys used in industrial production. China's automobile industry has grown in recent years, and die-casting aluminum alloy is now widely used in automotive parts, with new alloy types emerging at a rapid pace.

The most common die casting aluminum alloys are divided into three categories: Al Si alloy, which includes adcl and adc3; Al Si Cu alloy, which includes adc10, ADC12, adc14, and other alloys; and Al Mg alloy, which includes ADCs and adc6.

Die casting aluminum alloy properties and applicationsCopper can reduce the solidus, widen the solidification range, decrease the fluidity of liquid metal (increase the porosity), and increase the tendency of hot cracking in Al Si and Al Si Cu alloys; in addition, copper can reduce the solidus, widen the solidification range, decrease the fluidity of liquid metal (increase the porosity), and increase the tendency of hot cracking. Copper's solubility in aluminum is about 4%, so its content shouldn't be more than 4% 5%; iron content is typically between 0.7% and 1.2%. The demoulding effect of the workpiece is better at this ratio, but the iron element will form an intermetallic compound and reduce the casting's mechanical properties. Die castings with more than 2% iron content should be avoided. Al Mg alloy has a wide solidification range, a high tendency for shrinkage, shrinkage porosity and cracks, and poor casting performance. As a result, its range of application is severely limited, and it is unsuitable for the production of complex-structured workpieces.

Al Si aluminum alloys have better casting properties than other casting aluminum alloys, and because of the large solidification latent heat of silicon phase in the alloy, its specific heat capacity is greater and its linear shrinkage coefficient is lower, it has long held a dominant position in industrial production. The eutectic alloy AI-12si has a narrow solidification temperature range, excellent fluidity, and good mold filling ability, as well as less hot cracking and shrinkage porosity, making it a better casting alloy. It is widely used in die casting production to produce large, thin-walled, and complex-shaped die castings.

Defects in cast aluminum parts that peel

1. Cold-insulation microstructure
The discontinuity or unsteadiness of mold filling caused by the pressure change of liquid metal during die casting is referred to as cold shut micromorphology. When the local mold temperature is low, a small amount of liquid in the cavity will come into contact with the mold wall and solidify into a skin layer, which will be oxidized into a thin metal layer by water vapor and oil fumes, and then the metal liquid will cover the surface and solidify to form the interface. The surface layer is easy to peel off under the action of demoulding force, gas expansion force, and external forces such as high temperature, shot peening, and high pressure due to the oxidation phenomenon at the layer interface and the low bonding strength with the substrate.

2. Underneath the skin, there are micro pores.
The release of the subcutaneous air shrinkage cavity due to external force causes partial peeling. If there is no peeling on the casting's surface after direct die casting, but it appears after shot peening, the stronger the shot blasting or the longer the time, the more serious the peeling will be. Peeling defects caused by micro pores and bubbles on the surface or beneath the skin of the casting cause this.

3. There is a problem with the local surface density.
Due to insufficient surface compactness or poor meshing of local aluminum castings, partial peeling is caused by the failure of a dense layer under the action of external force. The phenomenon of semi-shedding of castings after shot blasting and high-pressure cleaning is caused by damage to the surface layer with a weak adsorption force under two times the pressure impact, resulting in flanging or shedding.

The solution of zinc die casting parts cleaning and grinding full sequence equipment is continuously introduced and promoted in China, based on such an environmental background and absorbing experience. Filling the industry gap with CNC grinding machine tools, robot grinding equipment, non-standard equipment, stamping equipment, and other items. The dust pollution caused by casting grinding has been eliminated, and the rate of product rejection is nearly zero. The goal of having no work-related injuries and no defective products in the workshop has been accomplished.