The weight and size range of cast aluminum parts are very wide. The lightest weight is only a few grams, the heaviest can reach 400 tons, the thinnest wall thickness is only 0.5 mm, the thickest can exceed 1 meter, and the length can be several millimeters to ten. A few meters can meet the requirements of different industrial sectors. Generally, for the appearance quality of aluminum castings, comparison samples can be used to judge the surface roughness of lost wax aluminum casting, and the fine cracks on the surface can be inspected by the coloring method and the magnetic powder method. The internal quality of aluminum castings can be inspected and judged by audio, ultrasonic, eddy current, X-ray and γ-ray methods.
The quality of aluminum castings has a great influence on the performance of mechanical products. For example, the size, accuracy and surface roughness of the impellers, casings and hydraulic parts of various pumps directly affect the working efficiency of pumps and hydraulic systems, energy consumption and the development of cavitation, etc. Internal combustion engine cylinders, The strength and shock resistance of aluminum castings such as cylinder heads, cylinder liners, piston rings, exhaust pipes, etc. directly affect the working life of the engine.
The principle of casting aluminum casting method selection: aluminum casting is preferred to sand casting. The main reason is that sand casting has lower cost than other casting methods, simple production process, and short production cycle. When the wet type cannot meet the requirements, consider using clay sand surface dry sand type, dry sand type or other sand types. The casting method of aluminum castings should be compatible with the production batch. Low pressure casting, die casting, centrifugal casting and other casting methods are only suitable for mass production because of the expensive equipment and molds. Aluminum castings can be cast in single pieces or mass production.
Shrinkage porosity of cast aluminum generally occurs in thick parts at the root of the fly riser near the inner runner, the wall thickness transition part and the thin wall part with a large plane. The fracture is gray in the as-cast state, and the light yellow is grayish white, light yellow or gray black after heat treatment.
Cleaning method of aluminum casting:
1. Casting shell cleaning: Generally speaking, aluminum castings can be further cleaned up after they are completely cooled. After the aluminum castings are cast in the shell, the cooling time of the castings in the mold is related to the material and lost wax aluminum casting. The shape and size of the parts are directly related to the production conditions. Generally, if the cleaning of aluminum alloy castings is done early, it will easily cause deformation and cracks of the aluminum castings. The cooling time of castings with larger size and more complicated process should be longer, and the cooling time of castings with smaller size and thin wall and simple process can be shorter.
2. Cutting pouring riser: The main methods of cutting pouring riser are: gas cutting, grinding wheel cutting, sawing machine, hydraulic cutting, anode cutting, etc.
3. Surface cleaning of aluminum castings: After the shelling of aluminum castings, there will always be iron oxide scale remaining on the surface of the castings, especially the castings with complex cavities, deep grooves, and blind holes, which cannot be cleaned completely, and surface cleaning must be performed .
4. Shot blasting treatment: If castings with special requirements can be shot blasting, shot blasting is to use the centrifugal force generated by the high-speed rotating shot blasting impeller to throw iron shots on the surface of the castings to make the surface of the cast aluminum Sand, sticky sand or iron oxide scale is removed. Generally speaking, the surface of the casting after shot blasting is related to the size of the iron shot.
5. Repair welding: usually refers to castings that do not meet the acceptance technical conditions or the requirements of the order agreement, and have casting defects but can be repaired. First of all, we must clean up the repair welding parts, so that the surface of the aluminum casting is completely clean and exposed to the metallic luster. The size of the defects should be welded from small to large. For example, the area of repair welding is large and the defects should be annealed after welding in important parts of the casting.
Aluminum castings have low cost, good manufacturability, remelting and regeneration to save resources and energy, so the application and development of this material are enduring. Such as research and development of cupola-electric furnace double smelting technology and equipment; extensive use of advanced molten iron desulfurization and filtration technology; thin-wall high-strength iron casting manufacturing technology; cast iron composite material manufacturing technology; iron casting surface or local strengthening technology; isothermal Yanghuo nodular cast iron complete set of technology; using metal mold casting, metal mold sand-coated casting, continuous casting and other special processes and equipment. Because of its low density, high specific strength, and corrosion resistance, cast lost wax aluminum casting light alloys will be more widely used in aviation, aerospace, automobile, machinery and other industries. Especially in the automobile industry, in order to reduce fuel consumption and improve energy utilization, it is a long-term development trend to replace steel and iron castings with aluminum and nickel alloy castings.
Among them, it focuses on solving pollution-free, high-efficiency, easy-to-operate refining technology, metamorphism technology, grain refinement technology and rapid detection technology before the furnace.
In order to further improve the material performance and maximize the potential of the material, high-quality aluminum alloy materials, especially aluminum-based composite materials, can be developed to meet the performance requirements of different working conditions; strengthen the research on the cluster alloy melting process, and continue the alloy die casting and squeeze casting Process and related technology development research; perfect ferroalloy smelting equipment and related technology and process development research.
Characteristics of cast aluminum parts:
Aluminum has strong stability and oxidation resistance, aluminum alloy castings will not rust and corrosion;
The surface adopts electrostatic powder spraying and fluorocarbon paint, and the various large-scale indoor and outdoor decorative products manufactured can keep the color for a long time.
Aluminum has good ductility and is convenient for various shapes and designs.
It has toughness, can be used repeatedly, and has a wider range of applications.
After various rigorous tests, the aluminum products’ resistance to earthquakes, wind pressure and weathering are guaranteed.
The unique aluminum alloy casting method makes the work weight lighter, reduces the burden in the handling and construction operations, and reduces the risk.