Liquid metal is poured into the mold cavity that is suitable for the shape and size of the part, and is cooled and solidified to obtain blanks or parts. It is usually called liquid metal forming or casting.
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sand casting
Casting method for producing castings in sand molds. Steel, iron and most non-ferrous alloy castings can be obtained by sand casting.
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technical features
Suitable for making blanks with complex shapes, especially with complex inner cavities;
Wide adaptability and low cost;
For some materials with poor plasticity, such as cast iron, sand casting is the only forming process for making parts or blanks.
application
Automobile engine cylinder block, cylinder head, crankshaft and other castings.
investment casting
Usually, it refers to making a pattern from a fusible material, covering the surface of the pattern with several layers of refractory material to make a shell, and then melting the pattern and discharging the shell, so as to obtain a mold without a parting surface, which can be filled after high-temperature roasting. The casting method of sand casting is often called "lost wax casting".
process flow
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Process characteristics
advantage
High dimensional accuracy and geometric accuracy;
High surface roughness;
It can cast castings with complex shapes, and the casting alloys are not limited.
shortcoming
The process is complicated and the cost is higher.
application
It is suitable for the production of small parts with complex shapes, high precision requirements, or difficult other processing, such as blades of turbine engines, etc.
Die casting
It uses high pressure to press molten metal into a precision metal mold cavity at high speed, and the molten metal is cooled and solidified under pressure to form a casting.
process flow
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Process characteristics
advantage
During die-casting, the metal liquid is under high pressure and the flow rate is fast;
Good product quality, stable size and good interchangeability;
The production efficiency is high, and the die-casting mold can be used more frequently;
It is suitable for mass production and has good economic benefits.
shortcoming
Castings are prone to fine porosity and shrinkage;
Die castings have low plasticity and are not suitable for working under impact loads and vibrations;
When die-casting high-melting point alloys, the life of the mold is low, which affects the expansion of die-casting production.
application
Die castings were first used in the automobile industry and the instrument industry, and then gradually expanded to various industries, such as agricultural machinery, machine tool industry, electronics industry, national defense industry, computers, medical equipment, clocks, cameras and daily hardware and other industries.
low pressure casting
It refers to the method of filling the mold with liquid metal under a lower pressure (0.02-0.06MPa) and crystallizing under pressure to form a casting.
process flow
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technical features
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;
Bottom injection type filling is adopted, the molten metal filling is stable without splashing, which can avoid the gas involved and the erosion of the mold wall and core, and improve the qualified rate of castings;
The casting crystallizes under pressure, the casting structure is dense, the outline is clear, the surface is smooth, and the mechanical properties are high, which is especially beneficial for the casting of large thin-walled parts;
The feeding riser is omitted, and the metal utilization rate is increased to 90% to 98%;
Low labor intensity, good working conditions, simple equipment, easy to realize mechanization and automation.
application
Mainly traditional products (cylinder heads, hubs, cylinder frames, etc.).
centrifugal casting
It is a casting method in which molten metal is poured into a rotating mold, and the mold is filled and solidified under the action of centrifugal force.
process flow
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Process characteristics
advantage
There is almost no metal consumption in the gating system and riser system, which improves the process yield;
When producing hollow castings, no core is needed, so the metal filling ability can be greatly improved when producing long tubular castings;
Castings have high density, fewer defects such as pores and slag inclusions, and high mechanical properties;
It is convenient to manufacture composite metal castings such as barrels and sleeves.
shortcoming
There are certain limitations when used to produce special-shaped castings;
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;
Castings are prone to specific gravity segregation.
application
Centrifugal casting was first used to produce cast pipes. At home and abroad, centrifugal casting technology is used in metallurgy, mining, transportation, drainage and irrigation 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.
metal mold casting
Refers to a forming method in which liquid metal fills a metal mold under the action of gravity and cools and solidifies in the mold to obtain a casting.
process flow
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Process characteristics
advantage
The thermal conductivity and heat capacity of the metal mold are large, the cooling speed is fast, the structure of the casting is compact, and the mechanical properties are about 15% higher than that of the sand casting;
Castings with high dimensional accuracy and low surface roughness can be obtained, and the quality stability is good;
Because sand cores are not used or rarely used, the environment can be improved, dust and harmful gases can be reduced, and labor intensity can be reduced.
shortcoming
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;
The metal type has no concession, and the casting is prone to cracks when it solidifies;
The metal mold manufacturing cycle is longer and the cost is higher. Therefore, good economic effects can only be shown when mass-produced in large quantities.
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 for the production of iron and steel metal castings and ingots.
Vacuum Die Casting
It is an advanced die-casting process that improves the mechanical properties and surface quality of die-casting parts by eliminating or significantly reducing the pores and dissolved gases in the die-casting parts by extracting the gas in the die-casting mold cavity during the die-casting process.
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Process characteristics
advantage
Eliminate or reduce the pores inside the die casting, improve the mechanical properties and surface quality of the die casting, and improve the coating performance;
To reduce the back pressure of the cavity, alloys with lower specific pressure and poor casting performance can be used, and it is possible to die-cast larger castings with small machines;
The filling condition is improved, and thinner castings can be die-cast.
shortcoming
The mold sealing structure is complicated, and the manufacturing and installation are difficult, so the cost is high;
If the vacuum die casting method is not properly controlled, the effect will not be very significant.
squeeze casting
It is a method of solidifying liquid or semi-solid metal under high pressure, flow forming, and directly obtaining workpieces 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.
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Direct Squeeze Casting
Spraying paint, pouring alloy, clamping mold, pressurizing, maintaining pressure, releasing pressure, parting mold, blank demoulding, reset.
indirect squeeze casting
Paint spraying, mold clamping, material feeding, mold filling, pressurization, pressure keeping, pressure relief, mold parting, blank demoulding, reset.
technical features
It can eliminate internal defects such as pores, shrinkage cavities and shrinkage porosity;
Low surface roughness and high dimensional accuracy;
Can prevent the generation of casting cracks;
It is convenient to realize mechanization and automation.
application
It can be used to produce various types of alloys, such as aluminum alloys, zinc alloys, copper alloys, ductile iron, etc.
Lost Foam Casting
It is to bond and combine paraffin or foam models similar in size and shape to castings to form a model cluster. After brushing refractory paint and drying, it is buried in dry quartz sand for vibration modeling, and poured under negative pressure to vaporize the model. Liquid metal A new casting method that occupies the position of the model and forms a casting after solidification and cooling.
process flow
Pre-foaming→foaming molding→dipping coating→drying→modeling→pouring→shaking out→cleaning
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technical features
The casting has high precision and no sand core, which reduces the processing time;
No parting surface, flexible design and high degree of freedom;
Clean production, no pollution;
Reduce investment and production costs.
application
It is suitable for the production of precision castings of various sizes with complex structures. The types of alloys are not limited, and the production batches are not limited. Such as gray cast iron engine case, high manganese steel elbow, etc.
continuous casting
It is an advanced casting method. Its principle is to continuously pour molten metal into a special metal mold called a crystallizer, and the solidified (crusted) casting is continuously pulled out from the other end of the crystallizer. , which can obtain castings of arbitrary length or specific length.
process flow
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technical features
Due to the rapid cooling of the metal, the crystallization is dense, the structure is uniform, and the mechanical properties are good;
Save metal and increase yield;
The process is simplified, and the modeling and other processes are exempted, thus reducing the labor intensity and greatly reducing the required production area;
Continuous casting production is easy to realize mechanization and automation to improve production efficiency.
application
The continuous casting method can 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.
