Casting is an ancient manufacturing method, which has a history of about 6000 years. With the continuous development of industrial technology, casting technology is becoming more and more mature. Now casting has appeared a new casting method, the following will introduce the advantages and disadvantages of common casting technology in detail.
Common casting processes are Sand casting, Investment casting, Pressure casting, Low-pressure casting, Centrifugal casting, Disappearing casting, Continuous casting.
Sand Casting
Definition: Sand casting usually relies on silica-based materials, put into the finished part model or wooden model (model), and then fill the sand around the model. After unpacking the model, the sand forms the casting model.
Advantage:
The cost of small-batch production is lower,
Compatible with common metals
Can cast large parts
Disadvantages:
Large castings have rough surfaces
Dimensional accuracy is not as good as other processes and requires larger tolerances
Application: Castings of automobile engine cylinder block, cylinder head, crankshaft, etc.
Investment Casting
Definition: Usually refers to making a pattern on a fusible material, covering the surface of the pattern with several layers of refractory material to make a shell, and then melting the pattern out of the shell to obtain a mold without a parting surface. Casting scheme that can be filled with sand. Often called "lost wax casting."
Advantage:
Accurate dimensional accuracy of castings
Casting ability of thin-walled parts with highly complex geometry
Smooth and clean surface
Can cast various metals
There is no parting line tolerance.
Disadvantages:
Higher production costs
The procedure is more complicated
Application: It can be used in aerospace, automotive, hydraulic accessories and other precision parts.
Pressure Casting
Definition: Die casting is a cavity that fills a steel mould with molten alloy liquid under high pressure at high speed. And the alloy liquid is solidified under pressure to form a metal casting.
Advantage:
High precision in die casting
Low surface roughness
High surface hardness of castings
High sound field efficiency, can be automated production
Disadvantages:
Unstable, not easy to heat-treat
Handle complex castings, die casting is more difficult
Not suitable for small batch production
Application: auto parts, furniture, bathroom hardware, electronic accessories.
Low-pressure Casting
Definition: Low-pressure casting is a method in which liquid metal fills a cavity under pressure to form a casting. Because of the low pressure used, it is called low-pressure casting.
Advantage:
Liquid metal forming is called stability
Smooth casting surface
High mechanical properties of castings
High moulding rate
Disadvantages:
The metal liquid is easy to oxidize
Application: Castings such as automobile wheels and cylinder heads of automobiles.
Centrifugal Casting
Definition: pouring liquid metal into the casting model rotating at high speed (250 ~ 1500r / min) to fill the casting model under the action of centrifugal force
Advantage:
When using centrifugal casting, the core, pouring system and riser can be omitted
The casting has a compact structure and good mechanical properties
Good filling ability
Disadvantages:
Not suitable for bronze, aluminium, magnesium and other alloys
Application: Used for sound field pipeline casting products, roulette castings.
Disappearing Casting
Definition: It is a combination of paraffin or foam model similar to the size and shape of the casting to form a model cluster. After being coated with refractory paint and dried, it is buried in dry quartz sand and vibrated. It is poured under negative pressure to vaporize the model. Liquid metal occupies the position of the model, a new casting method that forms a casting after solidification and cooling.
Advantage:
The casting has high precision and no sand core, which reduces the processing time;
No parting surface, flexible design and a high degree of freedom;
Clean production, no pollution;
Reduce investment and production costs.
Disadvantages:
Long production cycle
Higher initial cost
Application: It is suitable for producing various sizes of more precise castings with complex structure, unlimited alloy types and unlimited production batches. Such as grey cast iron engine box, high manganese steel elbow, etc.
Continuous Casting
Definition: It is a casting method in which liquid metal is continuously poured into the continuous crystallizer at one end and the molding material is continuously pulled out from the other end.
Advantage:
The mechanical properties of the casting are high
Improved yield
Simplified process
Application: Continuous casting can be used to cast long castings with constant cross-sectional shape, such as ingots, slabs, bar billets, pipes, etc., such as steel, iron, copper alloy, aluminium alloy, magnesium alloy.
Conclusion
The precision of castings obtained by various casting processes is different, the initial investment and productivity are also inconsistent, and the final economic benefits are also different. Therefore, to achieve more, faster, better, and more economical, all aspects should be taken into consideration.
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