Aluminum Die Casting VS Magnesium Die Casting VS Zinc Die Casting
Aluminum alloys are heavier than magnesium. Aluminum alloys can be used to obtain good mechanical and physical properties due to their excellent high corrosion resistance and good smooth appearance. Magnesium alloy die castings can cast thin-walled and complex products. Zinc die castings have good casting properties and can cast complex, thin-walled, high-precision and smooth surface shapes and parts. Zinc is the heaviest substance, so casting a small portion is recommended. Zinc has good surface preparation ability. By electroplating, spraying and painting, the surface is smooth.
1. Aluminum die castings
Aluminum alloy: the main alloying elements are copper, silicon, magnesium, zinc, manganese, and the secondary alloying elements are nickel, iron, titanium, chromium, lithium, etc.
Classification of aluminum alloys
Aluminum alloys are divided into two categories: cast aluminum alloys, which are used in the as-cast state; deformed aluminum alloys can withstand pressure processing, and their mechanical properties are better than those in the as-cast state. Aluminum alloy materials can be processed into various shapes and specifications. Mainly used in the manufacture of aviation equipment, daily necessities, building doors and windows, etc.
Processing method of aluminum alloy
Aluminum alloys can be divided into deformed aluminum alloys and cast aluminum alloys. Cast aluminum alloys can be divided into non-heat-treated aluminum alloys and heat-treated aluminum alloys. The mechanical properties enhanced by non-heat treatment cannot be improved by heat treatment, but only by cold working deformation. It mainly includes high-purity aluminum, industrial high-purity aluminum, industrial-purity aluminum and rust-proof aluminum. Aluminum alloys can improve mechanical properties by quenching and aging heat treatment. It can be divided into hard aluminum, forged aluminum, aluminum alloy and special aluminum alloy.
Properties of magnesium alloys
The specific gravity of magnesium is only 1.8g/cm3, the specific gravity of aluminum alloy is 2.7g/cm3, the weight of magnesium alloy is 30% lighter than that of aluminum alloy, and the weight of steel is 80% lighter than that of steel. As a result, magnesium alloys have become ideal materials for the manufacture of automotive and portable electronics components.
Magnesium alloys in metal and plastic engineering materials have excellent strength/weight ratios. The yield strength is 160MPa and the tensile strength is 240MPa.
Die casting properties
In the case of maintaining a good structure, the minimum wall thickness of magnesium alloys is allowed to reach 0.6mm, which cannot be achieved with the same strength. The die-casting performance of aluminum alloy is greater than 1.2-1.5mm, which is comparable to that of magnesium alloy. Magnesium alloys are easy to die cast and suitable for mass production (up to 1.5 times faster than aluminum). In addition, the wear of magnesium alloy molds is lower than that of aluminum alloys, mainly due to the high viscosity of aluminum.
Anti-vibration magnesium alloy has excellent damping performance, can absorb vibration and noise, and can be used as equipment shell to reduce noise transmission, prevent vibration, and prevent dent damage. Since LCD or LED are good choices.
Magnesium is twice as hard as aluminum and higher than most plastics. Magnesium has good stress resistance.
High EMI shielding
Magnesium alloy has good electromagnetic wave blocking function and is suitable for the production of electronic products.
good cutting performance
Magnesium has better machinability than aluminum and zinc, making it easier to cut metal materials.
Advantages of magnesium alloy materials and magnesium die castings
Magnesium alloys are lighter in all structures, accounting for 68% of aluminum alloys, 27% and 23% of zinc alloy steels. In addition, the shell and internal structure of its 3C products are also excellent materials for parts such as automobiles and airplanes.
strength and stiffness
The specific strength of magnesium alloy is significantly higher than that of aluminum alloy and steel, and the stiffness ratio is comparable to that of aluminum alloy and steel, much higher than that of engineering plastics. 10 times that of ordinary plastic.
Good vibration resistance
Under the same load, the damping capacity is 100 times that of aluminum and 300 to 500 times that of titanium alloys.
Good electromagnetic shielding performance
The shell of 3C products (mobile phones and computers) can provide excellent electromagnetic protection, while the magnesium alloy shell can absorb more than 100dB of electromagnetic interference frequency.
Good heat dissipation
The thermal conductivity of general metals is hundreds of times. The thermal conductivity of magnesium alloy is slightly lower than that of aluminum alloy and copper alloy, and the thermal conductivity of aluminum alloy and copper alloy is much higher than that of titanium alloy, and the heat is close to that of water.
stable supply of resources
The reserves of magnesium in the earth's crust ranks eighth. Most of the raw materials come from marine refining, so they are stable and abundant.
Defects of magnesium alloy die castings
Due to the extremely high filling and curing rates, the involved voids are easily created, which is very important for the handling of rubber, exhaust air and cold air. The casting cannot be too thick, and the wall thickness can only be limited to a certain size. Inexpensive die casting alloys have limited mechanical properties. The mobile phone industry restricts the use of die-casting alloy AZ91D castings, which have poor creep resistance due to small grain size. Poorly cast mg Al RE magnesium alloys are creep resistant6 and expensive. It cannot be heat treated, it is not suitable for welding and requires the use of shielding gas.
Zinc die casting
4-1 ZnAl is often used as the electro-galvanized base alloy material of our brand. Composition (%): Al 3.5～4.9, Cu 0.75～1.25, Mg 0.03～0.08, and the balance is Zn. The proportion is significant, and surface treatment can be carried out: electroplating, spraying, painting, casting, non-iron absorption, non-corrosion, pressure type, non-stick mold. Has good mechanical properties and wear resistance, low melting point, melting point 385 ℃, easy to cast.