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Analysis of Casting Process-Types of Die Casting

1. Sand Mould Casting

Sand casting refers to a casting method in which castings are produced in a sand mold.

Steel, iron and most non-ferrous alloy castings can be obtained by sand casting.

Sand Mould Casting

Because the molding materials used in sand mould casting are cheap and easy to obtain, the casting mold is simple to manufacture, and can be adapted to the single-piece production, batch production and mass production of castings, and has been the basic process in casting production for a long time.

Process Flow Diagrams, PFD

Sand Mould Casting PFD

Process Features

  1. The blank with very complex shape and cavity can be cast. Such as: all kinds of box, bed, frame and so on.
  2. Wide range of applicability, from a few grams to hundreds of tons of castings can be.
  3. The shape of the casting part is close to the size of the part, reducing the machining allowance.
2. Lost Wax Casting

It is still the method used to present the finest details of metal work. Such products are often difficult to manufacture because of their cumbersome design. Therefore, this method is still widely used in sculpture, jewelry processing, dentistry and industrial restoration.

lost wax casting


lost wax casting

Technological Characteristics 

  1. Realism is strong. It can reproduce subtle shapes and patterns.
  2. Jewelry can be molded at one time. (including complex and simple) save time and labor.
  3. The surface finish of the casting is good and the defects are few, which can reduce the workload of the polishing process and reduce the loss of metal materials.
  4. Various blanks can be produced in batches, and the streamlined production is convenient for management and quality control.
3. Pressure Casting

Pressure casting refers to a casting method in which molten or semi-molten metal is injected into a metal mold at high speed and crystallized under pressure, referred to as castings. The common injection pressure is 30-70MPa, the filling speed is about 0.5-50 m/s, and the filling time is 0.01-0.2 s.

pressure casting

Pressure Casting Process

pressure casting

Technics Characteristic

  1. High productivity, easy to realize mechanization and automation, and can produce thin-walled casting parts with complex shapes. The minimum wall thickness of die-casting zinc alloy is only 0.3mm, the minimum wall thickness of die-casting aluminum alloy is about 0.5mm, and the minimum casting hole diameter is 0.7mm.
  2. Casting parts have high dimensional accuracy and small surface roughness values. The dimensional tolerance level of die castings can reach CT3~CT6, and the surface roughness is generally Ra0.8~3.2μm.
  3. Parts can be embedded in casting parts, which not only saves precious materials and machining time, but also replaces the assembly process of components, which can save assembly processes and simplify manufacturing processes.
4. Low Pressure Casting

Low pressure casting means that the casting mold is generally placed above a sealed crucible, and compressed air is introduced into the crucible to cause a low pressure (0.06-0.15MPa) on the surface of the molten metal, so that the molten metal rises from the riser to fill the mold and control solidified casting method.

low pressure casting

This casting method has good feeding and compact structure of the casting, and it is easy to cast large and thin-walled and complex castings without a riser, and the metal yield is 95%. No pollution, easy to realize automation.

Technological Process

low pressure casting process

Technics Characteristics

  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 casting parts of various sizes.
  2. The bottom injection type filling is adopted, the metal liquid filling is stable, and there is no splashing phenomenon, which can avoid the involvement of gas and the scouring of the mold wall and core, and improve the qualification rate of casting parts.
  3. The casting parts crystallize under pressure, the castings are dense in structure, clear in outline, smooth in surface, and have high mechanical properties, which are especially beneficial for the casting of large and thin-walled parts.
  4. The feeding riser is omitted, and the metal utilization rate is increased to 90-98%.
5. Centrifugal Casting

Centrifugal casting is a technology and method of injecting liquid metal into a high-speed rotating mold, so that the metal liquid can be filled with a centrifugal motion to form a casting.

Centrifugal casting

Due to the centrifugal motion, the liquid metal can fill the mold well in the radial direction and form the free surface of the casting parts; A cylindrical inner hole can be obtained without a core;

Helps to exclude gas and inclusions in liquid metal; Affects the crystallization process of metal, thereby improving the mechanical and physical properties of casting parts.

Technological Process

Centrifugal casting process

Centrifugal casting process

Technological Characteristics

  1. Under the action of inertia force, the metal crystallization from the casting wall (outer layer of the casting) to the inner surface of the casting part, directional crystallization, slag, gas, inclusions and other concentrated in the inner surface of the casting part, the other parts of the casting structure is fine, no porosity, shrinkage, slag and other defects, the mechanical properties of the casting part is good.
  2. Centrifugal casting does not require a gating system and consumption of molten metal at risers.
6. Permanent Mold Casting

It refers to a molding method that liquid metal fills a metal mold under the action of gravity to cool and solidify to obtain a casting part.

Permanent Mold Casting

Technological Process

Permanent Mold Casting process

Technological Characteristics

  1. Permanent mold casting has large thermal conductivity and heat capacity, fast cooling rate, compact structure of casting parts, and mechanical properties about 15% higher than that of sand casting parts.
  2. Casting parts with higher dimensional accuracy and lower surface roughness values can be obtained, and the quality stability is good.
  3. Reduce dust and harmful gases.
7. Vacuum Die Casting

Vacuum Die Casting parts

Vacuum die casting is an advanced die-casting process that eliminates or significantly reduces the pores and dissolved gases in the die-casting part 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 part.

Vacuum Die Casting parts


Vacuum Die Casting process

Technological Characteristics

  1. Porosity is greatly reduced;
  2. The casting parts of vacuum die casting have high hardness and small microstructure;
  3. The mechanical properties of vacuum aluminum alloy die casting parts are relatively high.

The aluminum-magnesium alloy die-casting parts produced by vacuum die-casting have been proved to be able to be processed by welding, heat treatment and other processing methods, and the room temperature performance has also been improved to a certain extent:

For example, at present, the AM60B magnesium alloy automobile wheel is successfully produced by vacuum die casting method on the cold chamber die casting machine, and the AM60B magnesium alloy automobile steering wheel is produced by vacuum die casting method on the hot chamber die casting machine with the locking force of 2940kN, and the elongation of die casting parts is increased from 8% to more than 16%.

8. Squeeze Casting

Squeeze casting is a casting method in which alloy liquid is formed and solidified under mechanical pressure.

During squeeze casting, a large mechanical pressure is applied to the liquid (or semi-solid) metal quantitatively poured into the mold cavity to make it form, crystallize, solidify, and feed with a small amount of plastic deformation. This process The method was also called liquid metal die forging, liquid metal stamping, liquid metal forging, punch pressure crystallization, etc.

Squeeze Casting parts manufactured by yijin hardware


Squeeze Casting process

Technological Characteristics

  1. During squeeze casting, the molten metal is poured directly into the cavity without passing through the gating system, and the inhalation is less, and the casting part can be heat treated;
  2. There is no gating system during squeeze casting, the molten metal is filled under the action of pressure, the crystallization is solidified, the feeding effect is good, the grains are fine, and the structure is dense and uniform;
  3. The die structure of squeeze casting is simpler, the processing cost is lower, the service life is longer, and the utilization rate of metal is higher.
9. Cavityless Casting

Cavityless Casting parts manufactured by yijin hardware

It is to bond and combine paraffin or foam models similar in size and shape to casting parts into model clusters, brush refractory paint and dry them, bury them in dry quartz sand to vibrate for modeling, and pour them under negative pressure to vaporize the models and liquid metal.

A new casting method that occupies the position of the model and forms a casting after solidification and cooling.


Cavityless Casting parts manufactured by yijin hardware

Technological Characteristics

  1. The casting parts have high precision and no sand core, which reduces the processing time;
  2. No parting surface, flexible design, high degree of freedom;
  3. Clean production, no pollution;
  4. Reduce investment and production costs.
10. Continuous Csting

Continuous casting

Continuous casting is an advanced casting method whose principle is to pour molten metal into a special metal mold called a mold, and the solidified (crust) castings are continuously poured from the other end of the mold.

Pulled out, it can obtain castings of any length or specific length.


Continuous casting process

Technological Characteristics

  1. Due to the rapid cooling of the metal, compact crystallization, uniform structure, good mechanical properties;
  2. During continuous casting, there is no riser of the gating system on the casting, so the continuous casting does not need to cut the head and tail during rolling, which saves metal and improves the yield;
  3. The process is simplified, and the modeling and other processes are eliminated, thus reducing the labor intensity; the required production area is also greatly reduced;
  4. Continuous casting production is easy to realize mechanization and automation, and continuous casting and rolling can be realized during ingot casting, which greatly improves production efficiency.

Advantages of Die Casting:

1. Price Advantage

Why is there an advantage in the price of die castings?

Casting is suitable for both single-piece and small-batch production, as well as large-scale mass production. The investment in equipment is low, the cost of castings is low, and the source of raw materials is wide and the price is low.

Compared with the traditional material reduction production process (turning, milling, wire cutting, electrolysis), the die-casting production process causes almost no waste in the use of materials. Die-casting is to convert the raw materials into a liquid state through high temperature and then pour them into the mold to obtain parts. The metal scrap (casting, riser, waste casting) can be directly melted and used again;

die casting parts manufactured by YIJIN Hardware

Secondly, the production efficiency is also much simplified compared to the traditional subtractive processing process, usually one out of one or one out of many methods. Even if the die-casting parts need to be processed later, the processing allowance is very small. Just these points have resulted in significant savings in labor costs, power costs and material costs.

2. Capacity Advantage

It can manufacture parts or blanks of various sizes and complex shapes. The outline size can be as small as a few millimeters, as large as tens of meters, and the weight can be as small as a few grams and as large as hundreds of tons. There are also castings with complex inner cavities such as cylinder blocks, etc.

The shape and size of castings and machine parts can be the closest (especially precision casting), so the cutting allowance can be minimized, which reduces the consumption of metal materials and saves processing time;

Strong adaptability, casting method can cast various alloys (copper alloy, aluminum alloy, magnesium alloy, cast steel and cast iron, etc.), for brittle metals, such as cast iron, etc., casting is the only blank manufacturing method.