The moisture in the arc column atmosphere, the moisture absorbed by the welding material and the oxide film on the surface of the base metal are all important sources of hydrogen in the weld. High-temperature aluminum has very low strength, difficult to support the molten pool, and easy to weld through. During the welding process, a large amount of heat can be quickly transferred to the inside of the base metal. There is no obvious color change when the solid and liquid transition states, and it is difficult to judge during welding operations.

In tungsten argon arc welding, AC power is used to remove the oxide film through 'cathodic cleaning'. For example, the helium arc has a large heat, and the helium or argon-helium mixed gas is used for protection, or the large-scale molten electrode gas shielded welding is used. It hinders the melting and fusion of the base material, and the oxide film has a large specificity, which is not easy to surface, and it is easy to generate defects such as slag inclusion, lack of fusion, and incomplete penetration.

According to production experience, when the silicon content is 5% to 6%, thermal cracking will not occur, so the use of SAlSi (silicon content 4. The resulting aluminum oxide (Al2O3) has a high melting point and is very stable, making it difficult to remove. If the base metal of the base metal is deformation strengthening or solid solution aging strengthening, welding heat will reduce the strength of the heat-affected zone. When the silicon content of aluminum-silicon alloy is 0. When the aluminum welding molten pool is solidified, shrinkage cavities, shrinkage porosity, thermal cracks and high internal stress are prone to occur.

Therefore, measures must be taken to prevent welding deformation.Aluminum is a face-centered cubic crystal lattice without allotropes, and there is no phase change during heating and cooling. The weld grain is easy to be coarse, and the grain cannot be refined by phase change.5% to 6%) welding wire will have better crack resistance. China High pressure casting Aluminum has a strong ability to reflect light and heat.5%, the hot cracking tendency is greater. Therefore, the source of hydrogen must be strictly controlled to prevent the formation of pores. When welding thick plates, the welding heat can be increased. 　　

Alloy elements are easy to evaporate and burn, which reduces the weld performance. Where the corrosion resistance permits, aluminum-silicon alloy welding wire can be used to weld aluminum alloys other than aluminum-magnesium alloys. In the case of direct current connection, the 'cathode' is not required Clean up'. The thermal conductivity of aluminum is ten times that of austenitic stainless steel. In the process of solidification and rapid cooling of the weld pool, hydrogen is too late to overflow, and hydrogen pores are easily formed. 

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The cast alloy is not stable and is involved in gas. Correct selection and treatment of cold iron. Improve the design of the gating system. Poor gating system design Prevention method: The type (core) sand is mixed with organic impurities (such as coal cuttings, grassroots horse manure, etc. Improve the exhaust ability of (core) sand. Surface pores and bubbles can be found by sandblasting, and internal pores and bubbles can be found through X-ray fluoroscopy or mechanical processing to find that the pores and bubbles appear black on the X-ray film cause: 1. Poor ventilation of mold and sand core .

There are shrinkage holes on the surface of cold iron . No organic impurities should be mixed into the mold (core) sand to reduce the amount of gas generated by the molding material .Defect characteristics: The pores in the wall of the three castings are generally round or oval, with a smooth surface, usually shiny oxide skin, sometimes oily yellow. Correctly grasp the pouring speed to avoid getting involved in gas.) In order to solve the problem of high scrap rate of automotive aluminum castings and save the aluminum castings that may be scrapped due to the above-mentioned defects, certain treatment measures must be taken in the production.

After these defective castings are machined, the surface dense layer components are removed and the internal structural defects are exposed. Waste products, and these defects are often found only after machining and pressure testing, resulting in serious waste of working hours, raw materials and energy. The so-called 'impregnation' is to infiltrate the infiltrant into the micropores of aluminum castings under certain conditions.In the process of casting aluminum castings, it is easy to produce defects such as internal porosity, shrinkage holes, pores, etc.. For automotive cast aluminum parts with sealing requirements, such as cylinder blocks, cylinder heads, intake manifolds, brake valve bodies, etc.

At present, the most common technology is impregnation treatment, that is, leak plugging. After solidification, the filler that penetrates into the pores is connected to the inner wall of the casting pores to block the micropores so that the parts can Wholesale nonferrous casting parts suppliers be Process technology that meets the conditions of pressurization, seepage prevention and leakage prevention., when conducting pressure sealing tests, the existence of defective micropores will cause a large amount of leakage of the sealing medium                       

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When the engine is running, a small part of the oil is pumped from the oil pump and enters the filter through the oil port. Then it enters the rotor body through the oil hole and ejects from the two nozzles, so the ejection reaction force pushes the rotating hand to rotate. Under the action of the rotating centrifugal force, they are thrown to the rotor wall, and Attach the cover to the wall.

When the oil pressure is lower than 9s kPa, the oil inlet pressure limiting valve is closed and the fine filter does not work. When the oil pressure rises to 294 kPa, the speed of the rotor can reach 5000r/min or more, and the specific gravity of impurities in the lubricating oil in the rotor cavity is larger than that of the lubricating oil.When the oil pressure exceeds 98 kPa, the pressure limiting valve is gradually opened, and the oil is sprayed from the oil outlet through the center hole of the rotor shaft.

It is connected to the oil inlet of the oil pump. Float type oil filter, in order to make the oil pump work well, the large particles in the lubricating oil must be removed before entering the oil pump. A compression nut fastens the rotor cover and the rotor body together. In order to achieve a satisfactory filtering effect without increasing the resistance of Casting Automotive Mould Manufacturers the oil passage, the coarse filter is generally connected in series with the main oil passage, and the fine filter is connected in parallel with the main oil passage. The clean lubricating oil at the center enters the two nozzles from the center and continuously sprays outward, and the sprayed lubricating oil flows back to the lower crankcase.

It is mainly composed of upper cover, shell, paper filter element and bypass valve. parts-its function is to filter out smaller impurities in the lubricating oil. When the oil pump is working, the oil is sucked in from the slit between the cover and the float, filtered through the filter screen to remove coarse impurities, and then enters the oil pump through the oil pipe welded to the float. 

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Aluminum casting is due to the large latent heat of condensation to a certain extent. Aluminum casting has outstanding casting functions. Production costs should be reduced from the perspective of planning and technology, such as using one-mold multi-part skills and automation skills to increase production rates, extend mold service life, and use integrated planning to reduce the number of parts.

Pure aluminum and aluminum alloys have outstanding thermal conductivity, and are used in heat exchange equipment used in chemical production, as well as parts that require outstanding thermal conductivity on power machinery, such as cylinder heads and pistons of internal combustion engines., which make it widely loved by users, especially since the lightweight of cars, cast aluminum alloy castings have been used in the car industry Has been widely used.

Because of its low melting point, casting methods such as metal molds and pressure casting are widely used, which can improve the inner quality of its castings, its dimensional accuracy, appearance smoothness, and production power. The requirements for aluminum castings for cars are developed in the direction of thin wall, messy shape, high strength and high quality.. Under the same weight, the condensation process of molten aluminum is much longer than that of cast steel and cast iron at all times.

There are still many problems to be dealt with for aluminum casting to form its large-scale production and satisfy the requirements of lightweight cars.Aluminum casting has some incomparable advantages when used in other castings, such as its beauty, light weight, corrosion resistance, etc. The liquidity is excellent, which is beneficial to casting thin-walled and disorderly structured castings. Aluminum casting has outstanding appearance gloss and excellent corrosion resistance in the atmosphere Four Cylinder Head Manufacturers and water, so it has a wide range of uses in the production of civil utensils.

The density of cast aluminum alloy is lower than that of cast iron and cast steel, but the specific strength is higher. Pure aluminum has outstanding corrosion resistance in oxidizing acid media such as nitric acid and acetic acid, so aluminum castings also have certain uses in the chemical industry. Therefore, the selection of aluminum alloy castings under the same load conditions can reduce the weight of the structure. Therefore, in the aviation industry, power machinery and transportation machinery, Aluminum alloy castings are widely used. To get used to this requirement, the casting process should be further optimized and new alloy materials should be developed

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