Liquid metal is poured into the mold cavity suitable for the shape and size of the part, and is cooled and solidified to obtain the blank or part production method, which is usually called metal liquid forming or casting.
Casting:
1.sand casting
2.investment casting
3.die casting
4.low-pressure die casting
5.Centrifugal Casting
6.permanent mold casting
7.vacuum casting
8.squeeze casting
9.Lost Foam Casting
10.continuous casting
Sand casting
Casting method for producing castings in sand mold. Steel, iron and most non-ferrous alloy castings can be obtained by sand casting.
Technological process
Technical characteristics
● Suitable for making rough with complex shape, especially blanks with complex internal cavities;
● Wide adaptability and low cost;
● For some materials with very poor plasticity, such as cast iron, sand casting is the only forming process to manufacture their parts or blanks.
Application
Automobile engine cylinder block, cylinder head, crankshaft casting.
Investment casting
Usually refers to the fusible material made into a pattern, the surface of the pattern is coated with several layers of refractory material to make a shell, and then the pattern is melted out of the shell, so as to obtain the non-parting surface casting.The casting scheme that can be filled with sand after high temperature roasting is often called "lost wax casting".
Technological process
Technology characteristics
Advantage：
● High dimensional and geometric accuracy;
● High surface roughness;
● It can cast complex castings, and the alloy cast is not limited;
Disadvantage：
● The process is complicated and the cost is high.
Application
It is suitable for the production of small parts with complex shapes, high precision requirements, or difficult to carry out other processing, such as turbine engine blades.
Die casting
It uses high pressure to press liquid metal into a precision metal mold cavity at high speed, and the liquid metal cools and solidifies under pressure to form a casting.
Technological process
1. Die casting machine debugging
2. Installation of die-casting molds
3. Design and manufacturing of die-casting molds
4. Mold preheating and coating
5. Coating preparation
6. Mold cleaning
7. Mold closing (mold closing)
8.Alloy melting and heat preservation
9. Preparation of Insert
10. Pouring and injection molding
11. Maintaining pressure
12. Mold opening and core extraction
Technology characteristics
Advantage：
● The pressure of metal liquid is high and the flow rate is fast.
● Good product quality, stable size, good interchangeability;
● High production efficiency, die-casting mold use times;
● Suitable for mass production, good economic benefits.
Disadvantage：
● Castings are prone to small porosity and shrinkage;
● Die casting has low plasticity and should not work under impact load and vibration ;
● The die casting life of high melting point alloy is low, which affects the expansion of die casting production.
Application
Die casting parts were first used in the automotive industry and instrument industry, and later 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 die casting
It is a method of filling the mold with liquid metal under low pressure (0.02 ~ 0.06MPa) and crystallizing under pressure to form a casting.
Technological process
Technology characteristics
● The pressure and speed of pouring can be adjusted, so it can be applied to a variety of different molds (such as metal molds, sand molds, etc.), casting various alloys and castings of various sizes;
● The bottom filling type is adopted, the metal liquid filling is stable, no splashing phenomenon, can avoid the involvement of gas and the erosion of the mold wall and core, and improve the qualified rate of the casting;
● 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 advantageous for the casting of large thin-walled parts;
● Eliminating the feeding riser, the metal utilization rate is increased to 90% ~ 98%;
● 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.).
Centrifugal Casting
It is a casting method in which liquid metal is poured into a rotating mold and solidified by filling the mold under the action of centrifugal force.
Technological process
Technological Characteristic
Advantage：
● There is almost no metal consumption in the pouring system and riser system, which improves the process yield;
● The core can not be used in the production of hollow castings, so the metal filling ability can be greatly improved in the production of long tubular castings;
● The casting has high density, less defects such as porosity and slag inclusion, and high mechanical properties.
● It is convenient to manufacture composite metal castings of cylinder and sleeve.
Disadvantage：
● There are certain limitations in the production of special-shaped castings;
● The diameter of the inner hole is not accurate, the surface of the inner hole is rough, the quality is poor, and the processing allowance is large;
● Castings are prone to specific gravity segregation.
Application
Centrifugal casting was first used in the production of cast pipe, and centrifugal casting process is used at home and abroad in metallurgy, mining, transportation, drainage and irrigation machinery, aviation, national defense, automobile and other industries to produce steel, iron and non-iron carbon alloy castings. Among them, the production of centrifugal cast iron pipe, cylinder liner and shaft sleeve is the most common.
Permanent mold casting
It refers to a molding method in which the liquid metal fills the metal mold under the action of gravity and cools and solidifies in the mold to obtain the casting.
Technological process
Technological Characteristic
Advantage：
● The metal type has large thermal conductivity and heat capacity, fast cooling speed, dense casting structure, and mechanical properties about 15% higher than sand casting;
● The castings with higher dimensional accuracy and lower surface roughness can be obtained, and the quality stability is good.
● Because the sand core is not used and rarely used, it can improve the environment, reduce dust and harmful gases, and reduce labor intensity.
Disadvantage：
● The metal type itself is not permeable, and certain measures must be taken to derive the air in the cavity and the gas produced by the sand core.
● The metal type has no concession, and the casting is easy to crack when solidifying;
● Metal type manufacturing cycle is longer, the cost is higher. Therefore, good economic results can only be shown when a large number of batches are produced.
Application
Metal casting is not only suitable for mass production of complex shape of aluminum alloy, magnesium alloy and other non-ferrous alloy castings, but also suitable for the production of iron and steel metal castings, ingots and so on.
Vacuum casting
Advanced die casting processes that eliminate or significantly reduce pores and dissolved gases in die castings by removing the gas from the die cavity during die casting, thereby improving the mechanical properties and surface quality of die castings.
Technological process
Technological Characteristic
Advantage：
● Eliminate or reduce the porosity inside the die casting, improve the mechanical properties and surface quality of the die casting, improve the plating performance;
● Reduce the back pressure of the cavity.It can use a lower specific pressure and poor casting performance of the alloy, it is possible to use a small machine die casting larger castings;
● The filling condition is improved and thinner castings can be die-cast.
Disadvantage：
● Mold seal structure is complex, manufacturing and installation is difficult, so the cost is high;
● If the vacuum die casting method is not properly controlled, the effect is not very significant.
Squeeze casting
It is a method to make liquid or semi-solid metal solidify under high pressure, flow forming, and directly obtain parts or blanks. It has the advantages of high utilization rate of liquid metal, simplified process and stable quality. It is a kind of energy-saving metal forming technology with potential application prospect.
Technological process
Direct extrusion casting
Spray coating,casting alloy, closing mold, pressure, pressure holding, pressure relief, parting mold, blank stripping, reset.
Indirect extrusion casting
Spray coating, mold closing, feeding, filling, pressurization, pressure holding, pressure relief, mold parting, blank stripping, reset.
Technical feature
● The defects such as porosity, shrinkage and porosity can be eliminated.
● Low surface roughness, high dimensional accuracy;
● It can prevent casting cracks;
● 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 and so on.
Lost Foam Casting
It is a new casting method in which paraffin or foam models with similar size and shape to castings are bonded and combined into model clusters, and after brushing refractory paint and drying, it is buried in dry quartz sand for vibration modeling, and poured under negative pressure, so that the model is vaporized, the liquid metal occupies the position of the model, and the casting is formed after solidification and cooling.
Technological process
Pre-foaming → foam forming → dip coating → drying → molding → pouring → sand drop → cleaning
Technical feature
● High casting precision, no sand core, reduce the processing time;
● No parting surface, flexible design, high degree of freedom;
● Clean production, no pollution;
● Reduce investment and production costs.
Application
Suitable for the production of complex structure of various sizes of precision castings, alloy types are not limited, production volume is not limited. Such as gray cast iron engine box, high manganese steel elbow and so on.
Continuous casting
This is an advanced casting method, the principle is the molten metal, constantly poured into a special metal type called crystallize, solidified (crusted) castings, continuously pulled out from the other end of the crystallize, it can obtain any length or a specific length of castings.
Technological process
Technical feature
● Because the metal is cooled rapidly, the crystal is dense, the organization is uniform, and the mechanical properties are good.
● Save metal, improve yield;
● Simplify the process, eliminate modeling and other processes, thus reducing the labor intensity, the required production area is also greatly reduced;
● Continuous casting production is easy to achieve mechanization and automation, improve production efficiency.
Application
The continuous casting method can be used to cast steel, iron, copper alloy, aluminum alloy, magnesium alloy and other long castings with the same section shape, such as ingots, slabs, rods, pipes and so on.
Post time: May-12-2024
