Aluminum Alloy Low Pressure Casting

The casting crystallizes and solidifies under the action of pressure, and can obtain sufficient feeding, so the obtained casting has a denser structure and higher mechanical properties. For example, after T6 heat treatment of low-pressure castings, the tensile strength can reach 345-398MPa, the minimum elongation can reach about 2.5%, and the Brinell hardness HB can reach about 110-130. These mechanical properties are higher than gravity casting (popular Speaking of, low pressure casting is a compromise method between high pressure casting and gravity casting) Qinhuangdao Zhongwei Precision Machinery Co., Ltd. has been precipitation for more than 20 years. Castings, aluminum bronze and other castings have rich production experience. Manufacturers from various countries are expected to inquire about aluminum alloy low pressure casting.

Product Description

Aluminum alloy low pressure casting basic situation

1.Implementation standards: The company strictly implements ISO9001 & TS 16949 certification.

2. Product material standards: ISO, GB, ASTM, SAE, ISO, EN, DIN, JIS, BS

3. Main processes: sand casting, silica sol investment casting, water glass investment casting,shell casting,deburring, sand blasting, machining, heat treatment, leak testing, surface treatment, etc.

4. Available materials:

Aluminum alloy casting, silicon aluminum alloy casting, aluminum copper alloy casting, aluminum magnesium alloy casting, aluminum bronze, tin bronze, silicon bronze, aluminum bronze, brass, red copper, titanium alloy, high manganese steel, high chromium steel, high nickel steel , carbon steel, alloy steel, stainless steel, gray iron, , cast iron, cast steel, cast aluminum, etc. according to customer requirements.

Production Process

The pouring process parameters of aluminum alloy low pressure casting can be controlled manually and can be determined according to the different structures of the casting and the different materials of the casting mold. When pouring, the molten metal is filled under the action of controllable pressure, which can better control the filling speed and ensure the smooth filling of the molten metal, which can reduce and avoid the tossing, impact and splashing of the molten metal during filling. phenomenon, reduce the formation of slag inclusions, improve the quality of castings, reduce casting defects, and the pass rate can generally be controlled at about 90%. In the low pressure casting process, the utilization rate of molten metal is high, and the gating system is relatively simple, which can reduce the riser, and the molten metal that has not solidified can also be returned to the crucible, reducing losses. In addition, low-pressure casting has no special requirements for mold materials, and there are many materials suitable for molds, and the cost of molds is low (high-pressure casting is a metal mold, and the cost, cycle, and manufacturing requirements are relatively high). In addition, the equipment of low pressure casting is relatively simple, the one-time investment is relatively small, the floor space is small, and it is easy to realize automation.

In the process of low pressure casting, according to the type of castings and castings, the way of pressurization is also different, for example:

1.Low pressure charging. Only low-pressure filling is used, no crystallization pressurization is used (the mold is high, there are risers, and the casting is not closed). Sand low pressure casting is the most widely used, and this process can be used for some medium and large castings.

2. Stable crystallization. After the molten metal fills the cavity, the pressure is stabilized, and the casting is crystallized and solidified under this pressure until it is completely solidified. Generally suitable for casting of alloy green sand mold and metal mold thin-walled and complex castings.

3. Slowly pressurize and crystallize. After filling, the pressure is first stabilized, so that the surface of the casting is first solidified into a hard shell, and then the pressure is increased for crystallization and solidification. It is generally suitable for low-pressure sand casting, and thick-walled castings are usually poured. Due to the limitation of the strength of the casting mold, the crystallization pressure cannot be rapidly increased, so as to ensure that the castings can be crusted under constant pressure.

4. Rapid supercharging crystallization. After the molten metal fills the cavity, the pressure is rapidly increased to solidify the casting at a higher crystallization pressure, which is basically similar to the slow pressurized crystallization process, except that there is no stable crusting process after filling. It is generally suitable for low pressure casting of metal molds. For the rapid cooling and cooling of casting molds, with the advancement of the wave of lightweight automobiles, aluminum alloys are used more and more in automobiles due to their advantages of light weight and the same excellent strength performance. With the gradual replacement of fuel vehicles by electric vehicles, the application of aluminum alloys in automobiles will only increase, and will develop towards a large-scale trend, which puts forward new requirements for aluminum alloy die-casting technology. At present, in the process of aluminum alloy die-casting, there will be some defects due to materials, molds, technology, operator level, etc. There are surface defects, which are visible to the naked eye; there are also internal defects, which cannot be recognized by the naked eye. Usually, X-ray flaw detectors are used for detection. Eliminate defects and avoid quality problems caused by defective products.

Defects Of Aluminum Alloy Low Pressure Castings

● After the molten metal entering the cavity during the die-casting process forms a very thin and incomplete metal layer, it is compensated by the subsequent molten metal and leaves traces to produce visible defects;

● Too low mold temperature will also cause die casting defects;

● The cross-sectional area of the sprue is too small and not properly positioned to cause splashing.

● Insufficient pressure on the molten metal from the die casting machine can also cause internal porosity or external visible defects;

● Rough or cracked cavity surface of die-casting mold will bring obvious defects to die-casting parts;

● Improper die-casting mold material or incorrect heat treatment process, too large a change in the temperature difference between hot and cold die-casting die, too high pouring temperature, insufficient pre-heating of die-casting die, etc., resulting in die-casting defects;

● If the aluminum alloy contains too much zinc, iron, copper or other impurities, it will cause the defect of slag inclusion;

● Other defects caused by unreasonable die casting process, etc.

The above common aluminum alloy die-casting defects may directly affect the quality and performance of the die-casting parts. The surface defects are visible to the naked eye, and the die-casting process is optimized by checking the quality of materials, improving the level of technicians, and adjusting the process and equipment. , improve product quality. For the internal pores, air bubbles, looseness, and slag inclusions, it is necessary to use appropriate X-rays for non-destructive testing.

Post Casting Process

1. Heat treatment: annealing, carbonization, tempering, quenching, normalizing, surface tempering

2. Processing equipment: CNC, WEDM, lathe, milling machine, drilling machine, grinder, etc.;

3. Surface treatment: powder spraying, chrome plating, painting, sandblasting, nickel plating, galvanizing, blackening, polishing, bluing, etc.

Moulds and Inspection Fixtures

1. Mold service life: usually semi-permanent. (except for lost foam)

2. Mold delivery time: 10-25 days, (according to product structure and product size).

3. Tooling and mold maintenance: Zhongwei is responsible for precision parts.

Quality Control

1. Quality control: the defective rate is less than 0.1%.

2. Samples and trial run will be 100% inspected during production and before shipment, sample inspection for mass production according to ISDO standards or customer requirements

3. Testing equipment: flaw detection, spectrum analyzer, golden image analyzer, three-coordinate measuring machine, hardness testing equipment, tensile testing machine;

4. Provide after-sales service.

5. The quality can be traced back.

Application

Low pressure casting is the earliest anti-gravity casting technology, and it has been used in industrial production since the 1940s. Today, low-pressure casting is mainly used to produce aluminum alloy and magnesium alloy parts, such as automobile wheels in the automotive industry, cylinder blocks of internal combustion engines, cylinder heads, pistons, missile casings, impellers, wind guide wheels and other castings with complex shapes and high quality requirements . When using low pressure casting to produce aluminum alloy low pressure casting, such as cast steel wheels, special refractory materials should be used for the riser. Low pressure casting can also be applied to small copper alloy castings, such as pipe fittings, faucets in bathrooms, etc. This technology has been industrialized abroad.