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Dongguan Chengzhu Metal Products Co., Ltd.

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Introduction of magnesium alloy die casting process

Magnesium alloys have a wide range of uses. They can be used in many fields such as aerospace, medical, and electronic products. They are indispensable "many essential oils" in many industries. Magnesium alloy die-casting can be said to be one of its most important application technologies. The magnesium alloy die-casting process is similar to other die-casting processes, but due to the different characteristics of magnesium alloys, there are different places in the application of pressure, speed, temperature and coating .

 

Magnesium alloy die-casting is divided into two types: hot room and cold room. The pressure during die-casting is also different. The specific pressure of the hot chamber machine is about 40MPa, while the specific pressure of the cold room machine is usually 40-70MPa. Magnesium alloys have low inertia due to their low density. At the same time, because the magnesium alloy solidifies quickly, it is necessary to fill the entire cavity before the metal solidifies, so the injection speed of the magnesium alloy must be fast. In addition, the temperature is a thermal factor in the magnesium alloy die-casting process. In order to provide good filling conditions, ensure the molding quality of the die-casting parts, and control and maintain thermal stability, the corresponding temperature specification must be selected, which mainly refers to the casting temperature of magnesium alloy mold temperature. The function of the coating is to provide an effective insulation and protection layer between the die-casting alloy and the mold, and to prevent the metal liquid from directly flushing the cavity.

 

Advantages of magnesium alloy casting

  1. Light density, catering to the trend of automobile fuel-saving and lightening of home appliances; 2. Easy machining and cutting, the tool life is nearly doubled compared to aluminum alloy, and the surface finish is good; 3. Magnesium alloy castings have less porosity than aluminum alloy; 4. Compared with aluminum alloy die-casting, magnesium alloy die-casting is less, and workers are less labor-intensive. 5. Compared to aluminum alloy, magnesium-alloy casting has longer mold life and good maintenance. The mold can use more than 250,000 molds. 6. Compared with magnesium alloy, Aluminum alloy has less heat absorption from solid to liquid, and it is more energy-saving in the melting stage; 7. China is a large country of magnesium resources, the raw materials are stable, and the country encourages the use of magnesium alloys; Choice; 9. Magnesium alloy has better heat transfer performance, which can be used as the engine and machine cooling shell; 10. High strength, about 70% of aluminum alloy, which can replace aluminum alloy and be used in various aspects, with good prospects; The alloy has superior appearance quality and is not easy to age. It can replace plastics and can be used in various aspects with good prospects. 12. Magnesium alloys are relatively plastic and have electromagnetic shielding function. , Electrical fields may be used;
 

Characteristics of magnesium alloy

1. Light weight: The specific strength of magnesium alloy is higher than that of aluminum alloy and steel / iron, but slightly lower than the fiber reinforced plastic with the highest specific strength; its specific stiffness is equivalent to that of aluminum alloy and steel / iron, but it is much higher than fiber Reinforced plastic. Specific strength (ratio of strength / density) and specific endurance (ratio of endurance / density) are higher than aluminum and iron. Among metal structural materials, its specific gravity is the smallest (the density is 2/3 of aluminum and 1/4 of steel). Under the same rigid conditions, the strength of a 1kg magnesium alloy is equivalent to 18kg of aluminum or 2.1kg of steel. For the same complicated parts, when using a magnesium alloy, its weight is 1/3 lighter than tin and 1 / lighter than steel. 2. This feature is of great significance for reducing the weight of portable products and reducing the energy consumption of vehicles in modern society.

 

2. High damping, shock absorption and shock absorption performance: Magnesium alloy has excellent ability to absorb energy, can absorb vibration and noise, and ensure that the equipment can work quietly. This characteristic is used as the equipment casing to reduce noise transmission and improve anti-vibration. Impact and prevention of dent damage are very beneficial; the use of magnesium alloy materials as structural parts of the car is very helpful to reduce the noise and vibration of the car in motion. In addition, the magnesium alloy has dozens of times greater damping than aluminum alloy, and the shock absorption effect is very significant. Using magnesium alloy instead of aluminum alloy to make the base of computer hard disk can greatly reduce the weight (about 70%) and greatly increase the stability of hard disk. Performance is very conducive to the development of high-speed, high-capacity computer hard disk.

 

3. Good impact resistance and compression resistance: its impact resistance is 20 times that of plastic. When magnesium alloy castings are impacted, the scars on their surfaces are much smaller than iron and aluminum. Magnesium alloy has the characteristics of absorbing elasticity and can produce a good combination of impact strength and compressive strength. This is one of the reasons why magnesium alloy die-casting parts are used in the cover of rotary lawn cutters.

 

4. Good casting performance: Under the condition of maintaining good component structure, the wall thickness of magnesium alloy castings can be less than 0.6mm, which cannot be achieved by plastic products under the same strength conditions, while aluminum alloy products can only be used at 1.2 It can be compared with magnesium products in the range of ~ 1.5mm.

 

5. Dimensional stability: Below 100 ℃, magnesium alloy can maintain its dimensional stability for a long period of time (in fact, almost no change in the size of the workpiece can be observed); dimensional stability is not required for annealing and stress relief A very prominent feature, its volume shrinkage is only 6%, which is the lowest type of shrinkage in cast metals; under load, it also has good creep strength. This performance is useful for making engine parts and small engine die-castings. Is of great significance.

 

6. High mold productivity: Compared with aluminum alloy, magnesium alloy has a lower unit heat content, which means that it can solidify faster in the mold. In general, the productivity of magnesium alloys is 40% to 50% higher than that of aluminum die-casting, and up to twice that of aluminum die-casting.

 

7. Good machining performance: The cutting resistance of magnesium alloy is small, about 1/10 of that of steel and 1/3 of that of aluminum alloy. Its cutting speed is much higher than other metals, and the cutting time is short; Other metals have several times the tool life (very few shutdowns and tool changes, saving operating time and tool costs); easy to cut and low processing costs, and the processing energy is only 70% of aluminum alloy. No mechanical grinding and polishing are needed, and excellent surface finish can be obtained without using cutting fluid. It can be obtained after one cutting, and rarely has chippings; good chip breaking characteristics and temperature conductivity, which can be eliminated Coolant or lubricant.
 

 

8. Good corrosion resistance: In the atmosphere, magnesium has good corrosion resistance, which is better than iron. For example, the corrosion resistance of high-purity magnesium alloy AZ91D is much better than that of low-carbon steel, which has exceeded the die-cast aluminum alloy A380. In addition, beryllium and calcium in magnesium alloys can improve their corrosion resistance, while iron, cobalt, nickel, and copper in magnesium alloys The presence of silicon has significantly reduced its corrosion resistance.

 

9. High heat dissipation: Magnesium alloy has high heat dissipation, which is very suitable for making electronic products with dense components. Magnesium alloy has a thermal conductivity of 350 to 400 times that of ABS resin. Therefore, when manufacturing electronic product housings or parts, it can make full use of the heat dissipation function and timely discharge the heat generated by electronic components such as CPU. If only considering from the perspective of heat dissipation of laptops and other products, magnesium alloys are undoubtedly the best choice because of the rapid heat transfer of magnesium alloys and the fact that they are not easy to get hot.

10. Good electromagnetic interference barrier: magnesium alloy has better magnetic shielding performance than aluminum alloy, better electromagnetic wave blocking function, and is more suitable for making electronic products that emit electromagnetic interference. Can be used as the shell of computers, mobile phones and other products to reduce the electromagnetic radiation harm to human body.

11. Low heat capacity: The heat capacity of magnesium alloy is smaller than that of aluminum alloy, it is not easy to stick to the mold and prolong the life of the mold.

12. Recyclability: Waste magnesium alloy castings have the characteristics of being recyclable and remeltable, and can be re-casted as secondary materials of AZ91D, AM50, AM60. Due to the growing demand for die castings, the ability to be recycled is very important. This meets environmental requirements and makes magnesium alloys more attractive than many plastic materials. Under the environment of rising environmental awareness. In the future, the impact of environmental awareness on business behavior will become more and more important. Factors that meet environmental protection regulations will inevitably overwhelm cost, function, and other factors, and will become the key preferred factors that dominate the survival of products. Get highly valued. In addition, magnesium alloys also have the characteristics of fatigue resistance, non-toxicity, non-magnetism, low tendency to crack, and not easy to crack, which can be suitable for some specific fields.

 

Application of magnesium alloy

 

With the continuous development and promotion of magnesium alloy forming technology, magnesium alloy die-casting structural parts will be more and more widely used in automobiles, home appliances, communications electronics, light tools, aerospace, military industry and other fields, and their consumption proportion will be dramatic. Increased to more than 60%. At present, magnesium alloys (die-casting parts) are mainly used in die-casting products such as mobile phones, notebook computer casings, and decorative parts. They are also widely used in automotive and home appliance manufacturing industries.

1. Automobiles: Generally used to make seat skeletons, instrument panels / boards, steering wheels / steering wheels and steering columns, roof covers, gear boxes, door frames, wheels, automobile rear wheel covers, and cylinders of automobile engines. (Top) cover, cylinder block, bracket, transmission case, clutch case, fuel tank bottom case, dust plate, valve cover, air intake valve and air purifier cover, bracket, ring, steering wheel damping shaft, motor, Intake manifolds, security parts and other parts (among them, steering wheel, steering column and wheel hub are the parts with more magnesium alloys). We believe that with the continuous development of related technologies, more automotive parts will be made of magnesium alloys.

2. Mobile phone: Because magnesium alloy has the characteristics of anti-vibration and anti-wear, especially the special function of shielding electromagnetic waves, it is extremely important for mobile phones. These characteristics can help eliminate consumers' doubts about whether the electromagnetic waves of the machine will affect human health. Although the cost of magnesium alloys is still relatively high, magnesium alloys will surely win the favor of mobile phone manufacturers and consumers because of their light texture, high temperature resistance, strong plasticity, and strong antimagnetic ability.

3. Notebook computer case: The current notebook computer case emphasizes the characteristics of good heat dissipation, light weight, sturdy and durable, and bright colors. The materials of laptop shells on the market include ABS plastic, carbon fiber, aluminum-magnesium alloy, and titanium alloy. However, in general, the materials that are currently more popular in the market and consumers are aluminum-magnesium alloy and titanium alloy products. Among them, the thickness of the single sheet of the magnesium alloy product is about 1.0 mm, which is light in weight and good in ductility. The development momentum of magnesium alloys is even more promising.

4. Precision instruments: The impact resistance of magnesium alloy makes it more suitable for making high-rigidity integral components and impacted parts, such as instrument housings and bases. It plays the role of damping and damping when transmitting vibration, which can improve the sensitivity and stability of the instrument.

5. National defense and aerospace: Gearboxes and horizontal rotor accessories for military helicopters, landing wheels, gearbox covers, anti-tank grenades, light tanks and some parts of armored ambulances, cylinder blocks, cylinder heads, variable speeds Case, missile housing and tail, radar locator housing, etc. In addition, magnesium alloys can also be widely used in the production of casings for handheld cameras, camcorders, projectors, video recorders, chainsaws, lawn mowers, rechargeable batteries, microphones, headphones, MD players and CD players, palmtop computers (ie, handheld HPCs), Decorative parts for home appliances such as televisions.

The application of magnesium alloy was briefly introduced. The application of magnesium alloys in automobiles has also been mentioned above. Then we will introduce in detail the application of magnesium alloys in automobiles. Since the oil crisis in the Middle East in 1970, in order to reduce the quality of automobiles to reduce fuel consumption and pollution, improve safety performance, the application of magnesium alloy materials in the automotive industry has been increasing. At present, the regions and countries with a large amount of magnesium alloys in the automotive industry are mainly North America, Europe, Japan, and South Korea. Based on the usage of some manufacturers, so far, more than 60 parts of automobiles have used magnesium alloys:

1.Interior components: dashboard, seat frame, seat lifter, control platform, airbag cover, steering wheel, locking device cover, steering column, steering column bracket, radio case, gadget box door, window motor Covers, brake and clutch pedal brackets, pneumatic bracket pedals, etc.

2. Car body components: door frames, tail panels, roof frames, roof panels, IP beams, etc.

3.Engine and transmission system: valve cover, cam cover, four-wheel drive gearbox, manual shift transmission, clutch housing piston, intake pipe, oil pan, AC motor bracket, transmission housing, gear box housing, oil filter Connector, motor cover, cylinder head cover, distribution plate bracket, oil pump housing, fuel tank, oil filter bracket, left half crankcase, right half crankcase, empty hood, left suction pipe, right suction pipe, etc.

4. Chassis: wheel hub, engine bracket, front and rear booms, rear bracket.

 

Types of magnesium alloys


1、Alloy name

The alloy name of the magnesium alloy is based on the main added alloying elements and their percentages.。

2、Composition of major alloys(ASTMspecification)

Alloy name Mg Al Zn Mn Si Cu Ni Fe

AZ91D bal. 8.5-9.5 0.45-0.90 0.17-0.4 <=0.05 <=0.025 <=0.001 <=0.004

AM60B bal. 5.6-6.4 <=0.20 0.26-0.5 <=0.05 <=0.008 <=0.001 <=0.004

AM50A bal. 4.5-5.3 <=0.20 0.28-0.5 <=0.01 <=0.008 <=0.001 <=0.004

AS41B bal. 3.7-4.8 <=0.10 0.35-0.60 0.6-1.4 <=0.015 <=0.001 <=0.0035 

3、Features and applications of major alloys

Alloy name Feature                    Application range

AZ91D High strength and good corrosion resistance     Cases for electrical products, etc.

AM60B High elongation and impact resistance           Steering wheels and seats on cars

AM50A High elongation and impact resistance           Steering wheels and seats on cars 

AS41B Good creep resistance           Gearboxes on cars, etc.

 

 

magnesium alloyAZ91D

magnesium alloyAZ91DIs mainly relying on pressure mold casting auxiliary,Is characterized bystrengthHigh and corrosion resistance is greatly improved compared to pure magnesium. It is mainly used for housings of electrical products, small size thin or special-shaped brackets, etc.。

Concept

 

AZ91DBelongs to castingmagnesium alloyIt is mainly processed by means of pressure die casting and subsequent processing. The appearance can be changed by surface methods such as electrophoresis. Is characterized byStrengthHigh and corrosion resistance is greatly improved compared to pure magnesium. It is mainly used for housings of electrical products, small size thin or special-shaped brackets. A represents metal aluminum Al, Z represents metal zinc Zn, 9 represents aluminum content of 9%, 1 represents zinc content of 1%, and the last D is identification code. (GB GB/T5153-2003)

ingredient

name

Mg

Al

Zn

Mn

Si

Cu

Ni

Fe

AZ91D

margin

8.5-9.5

0.45-0.90

0.17-0.4

<=0.05

<=0.025

<=0.001

<=0.004

performance

Material name

density(g/cm3)

Melting point(℃)

Thermal Conductivity(W/Mk)

tensile strength(MPa)

Yield point(MPa)

Elongation(%)

Specific strength

Young's modulus(GPa)

AZ91D

1.82

596

72

250

160

7

154

45

magnesium alloyAM60B

AM60Bmagnesium alloyMg-Al-Mn alloy。AM60Bmagnesium alloyThe main feature of the alloy is that it has good wear resistance and strong corrosion resistance. AM60B has a density of about 1.8, making it the lightest metal material. AM60B has a large elastic modulus, good heat dissipation, and good shock absorption. Magnesium alloy AM60B has a large ability to withstand impact loads and good resistance to organic and alkali corrosion.。

magnesium alloyFeatures and benefits of die casting

magnesium alloyFeatures of Die Casting: Can be die casted according to different designs, sizes, and requirements

magnesium alloyAdvantages of die-casting: lighter weight and stronger rigidity than aluminum alloy; environmentally friendly material than plastic, high hardness and anti-magnetic interference

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Dongguan City - Casting Metal Products Co., Ltd
Address: Liao Bu Town, Dongguan City, Guangdong Province, Tong Lip Village Street
Telephone:86-769-22654041
Fax:86-769-22654043
URL:http://www.mag-alloy.com
E-mail:zhaochenghuang168@163.com
Integrity - enterprise:zch13825787603
businessQQ:425090969
Phone:13825787603