Detailed explanations of the top ten casting process graphics and texts

Process flow: liquid metal→filling→solidification shrinkage→casting

Process characteristics:

1. It can produce parts with arbitrarily complex shapes, especially parts with complex inner cavity shapes.

2. Strong adaptability, unlimited alloy types, almost unlimited casting size.

3. There are wide sources of materials, waste products can be remelted, and equipment investment is low.

4. High scrap rate, low surface quality and poor working conditions.

Casting classification:

（1）sand casting

Sand casting: A casting method for producing castings in sand. Steel, iron and most non-ferrous alloy castings can be obtained by sand casting methods.

Process flow:

Sand casting process

Technical features:

1. It is suitable for making blanks with complex shapes, especially with complex inner cavities;

2. Wide adaptability and low cost;

3. For some materials with poor plasticity, such as cast iron, sand casting is the only forming process for manufacturing its parts or blanks.

Application: automobile engine cylinder block, cylinder head, crankshaft and other castings

（2）investmentcasting

Investment casting: usually refers to making a pattern made of fusible materials, covering the surface of the pattern with several layers of refractory materials to form a shell, and then melting the pattern out of the shell to obtain a mold without a parting surface. After high temperature baking Then, the casting program can be filled with sand and poured. Often referred to as "lost wax casting".

Process characteristics

advantage:

1. High dimensional accuracy and geometric accuracy;

2. High surface roughness;

3. It can cast complex castings, and the cast alloy is not limited.

Disadvantages: complicated procedures and high cost

Application: Suitable for the production of small parts with complex shapes, high precision requirements, or other processing difficulties, such as turbine engine blades.

（3）die casting

Die casting: It uses high pressure to press molten metal into a precision metal mold cavity at high speed. The molten metal is cooled and solidified under pressure to form a casting.

Process characteristics

advantage:

1. The metal liquid is subjected to high pressure during die-casting, and the flow rate is fast

2. Good product quality, stable size and good interchangeability;

3. The production efficiency is high, and the die-casting mold is used many times;

4. It is suitable for mass production with good economic benefits.

shortcoming:

1. Castings are prone to small pores and shrinkage porosity.

2. Die-casting parts have low plasticity and are not suitable to work under impact load and vibration;

3. When high melting point alloy is die-casting, the mold life is low, which affects the expansion of die-casting production.

Application: Die castings were first used in the automobile industry and instrument industry, and then gradually expanded to various industries, such as agricultural machinery, machine tool industry, electronics industry, defense industry, computer, medical equipment, clocks, cameras, daily hardware and other industries .

（4）low pressure casting

Low pressure casting: refers to the method of filling the mold with liquid metal under lower pressure (0.02～0.06MPa) and crystallizing under pressure to form castings.

Process flow:

Technical features:

1. The pressure and speed during pouring can be adjusted, so it can be applied to various casting molds (such as metal molds, sand molds, etc.), casting various alloys and castings of various sizes;

2. Bottom injection type filling is adopted, the filling of molten metal is stable, and there is no splashing phenomenon, which can avoid the entrapment of gas and the erosion of the wall and core, which improves the qualification rate of castings;

3. The casting crystallizes under pressure, the structure of the casting is dense, the outline is clear, the surface is smooth, and the mechanical properties are high, which is especially advantageous for the casting of large and thin-walled parts;

4. The feeder riser is omitted, and the metal utilization rate is increased to 90-98%;

5. Low labor intensity, good working conditions, simple equipment, easy to realize mechanization and automation.

Application: Mainly traditional products (cylinder head, wheel hub, cylinder frame, etc.).

（5）centrifugal casting

Centrifugal casting: is a casting method in which molten metal is poured into a rotating mold, and the mold is filled under the action of centrifugal force to solidify and shape.

Process flow:

Process characteristics

advantage:

1. There is almost no metal consumption in the gating system and the riser system, which improves the production rate of the process;

2. The core can be omitted when producing hollow castings, so the metal filling ability can be greatly improved when producing long tubular castings;

3. Castings have high density, few defects such as pores and slag inclusions, and high mechanical properties;

4. It is convenient to manufacture barrel and sleeve composite metal castings.

shortcoming:

1. There are certain limitations when used in the production of special-shaped castings;

2. The diameter of the inner hole of the casting is not accurate, the surface of the inner hole is relatively rough, the quality is poor, and the machining allowance is large;

3. Castings are prone to segregation of specific gravity.

application:

Centrifugal casting was first used to produce cast pipes. At home and abroad, centrifugal casting was used in metallurgy, mining, transportation, irrigation and drainage machinery, aviation, national defense, automobile and other industries to produce steel, iron and non-ferrous carbon alloy castings. Among them, the production of castings such as centrifugal cast iron pipes, internal combustion engine cylinder liners and shaft sleeves is the most common.

（6）gravity die casting

Metal mold casting: refers to a molding method in which liquid metal is filled with a metal mold under the action of gravity and cooled and solidified in the mold to obtain a casting.

Process flow:

Process characteristics

advantage:

1. The thermal conductivity and heat capacity of the metal mold are large, the cooling rate is fast, the structure of the casting is dense, and the mechanical properties are about 15% higher than that of the sand casting.

2. Castings with higher dimensional accuracy and lower surface roughness values can be obtained, and the quality stability is good.

3. Because sand cores are not used and rarely used, the environment is improved, dust and harmful gases are reduced, and labor intensity is reduced.

shortcoming:

1. The metal mold itself has no air permeability, and certain measures must be taken to export the air in the cavity and the gas generated by the sand core;

2. The metal mold has no retreat, and the casting is prone to cracks when it solidifies;

3. The metal mold has a longer manufacturing cycle and higher cost. Therefore, only in mass production, can it show good economic results.

Application: Metal mold casting is not only suitable for mass production of non-ferrous alloy castings such as aluminum alloys and magnesium alloys with complex shapes, but also suitable for the production of iron and steel metal castings, ingots, etc.

（7）vacuumdie casting

Vacuum casting: An advanced die-casting process that eliminates or significantly reduces the pores and dissolved gases in the die-casting parts by removing the gas in the die-casting mold cavity during the die-casting process, thereby improving the mechanical properties and surface quality of the die-casting parts.

Process flow:

advantage:

1. Eliminate or reduce the pores inside the die casting, improve the mechanical properties and surface quality of the die casting, and improve the plating performance;

2. To reduce the back pressure of the cavity, lower specific pressure and alloys with poor casting properties can be used, and it is possible to die-cast larger castings with a small machine;

3. The filling conditions are improved, and thinner castings can be die-casted;

shortcoming:

1. The mold sealing structure is complex, making and installing more difficult, so the cost is higher;

2. If the vacuum die-casting method is improperly controlled, the effect is not very significant.

（8）squeezing die casting

Squeeze casting: is a method of solidifying, flowing and forming liquid or semi-solid metal under high pressure to directly obtain parts or blanks. It has the advantages of high utilization rate of liquid metal, simplified process and stable quality. It is an energy-saving metal forming technology with potential application prospects.

Process flow:

Direct squeeze casting: spray paint, cast alloy, close mold, pressurize, hold pressure, release pressure, split mold, demold blank, reset;

Indirect squeeze casting: spray coating, mold clamping, feeding, filling, pressurization, pressure holding, pressure relief, mold splitting, blank demolding, resetting.

Technical features:

1. It can eliminate internal defects such as pores, shrinkage holes and shrinkage porosity;

2. Low surface roughness and high dimensional accuracy;

3. It can prevent casting cracks;

4. It is easy to realize mechanization and automation.

Application: It can be used to produce various types of alloys, such as aluminum alloy, zinc alloy, copper alloy, ductile iron, etc.

（9）Lost foam casting

Lost foam casting (also called solid casting): It is to combine paraffin wax or foam models similar in size and shape to the castings to form clusters. After brushing and drying refractory coatings, they are buried in dry quartz sand for vibration modeling. It is a new type of casting method in which the mold is vaporized by pouring under pressure, the liquid metal occupies the position of the mold, and the casting is formed after solidification and cooling.

Process flow: Foam pattern→Clustering→ Coating→Drying→Compaction→Casting→falling out→cleaning

Technical features:

1. The casting has high precision and no sand core, which reduces the processing time;

2. No parting surface, flexible design and high degree of freedom;

3. Clean production, no pollution;

4. Reduce investment and production costs.

Application: It is suitable for the production of precision castings of various sizes with complex structures, unlimited types of alloys, and unlimited production batches. Such as gray cast iron engine box, high manganese steel elbow, etc.

（10）continual casting

Continuous casting: It is an advanced casting method. Its principle is to continuously pour molten metal into a special metal mold called a mold. The solidified (crusted) castings are continuously removed from the mold. Pull out one end, it can get any length or specific length casting.

Process flow:

Technical features:

1. Since the metal is cooled rapidly, the crystal is dense, the structure is uniform, and the mechanical properties are good;

2. Save metal and increase yield;

3. The process is simplified, modeling and other processes are eliminated, thus reducing labor intensity; the required production area is also greatly reduced;

4. Continuous casting production is easy to realize mechanization and automation, and improve production efficiency.

Application: Continuous casting method can be used to cast steel, iron, copper alloy, aluminum alloy, magnesium alloy and other long castings with constant cross-sectional shape, such as ingots, slabs, billets, pipes, etc.

END