Do you know the different types of casting processes? At present, the foundry industry is developing very rapidly. There are also many types of casting processes. Next, I will introduce you to the top ten casting processes.
1 .Sand casting:
Sand casting is a casting method that produces castings in sand molds.
- Mix the sand with a sand mixer and add appropriate clay for mixing.
- Manufacturing molds for casting.
- Put the mold into the sand mixture, and then seal the box containing the sand mixture.
- Distribute according to the metal to be cast and select a suitable melting furnace to melt the metal. Know that metal melts into liquid metal.
- Pour the liquid metal prepared in the previous step into the desired mold. (This process is dangerous, pay attention to safety)
- After the liquid metal has cooled and solidified in the mold, use a tool to clean up the grit around the cast part.
Technical characteristics of sand casting :
- It is suitable for making blanks with complex shapes, especially with complex inner cavities;
- Wide adaptability and low cost;
- For materials with poor plasticities, such as cast iron. Sand casting is the only forming process for manufacturing cast iron parts or blanks. It can use in automobile engine cylinder blocks, cylinder heads, crankshafts, and other castings.
- Choose a material that is easy to melt to make the mold. The surface of the mold can cover with several layers of refractory material to make the shell of the casting part.
- Melt the cast iron mold again. In this way, can obtain a complete casting model.
- After high-temperature roasting, it should fill with sand and pour. This is the process of investment casting. Also often referred to as “lost wax casting.”
Technical characteristics of investment casting process:
- Investment casting has high dimensional accuracy and geometric accuracy. Suitable for industrial precision casting parts.
- High surface roughness.
- It can cast complex castings, and the cast alloy is not limited.
- The process does complicate. And the cost is high.
- It is suitable for the production of small parts with complex shapes, high precision requirements, or other processing difficulties, such as turbine engine blades.
1.Using high pressure to press molten metal into a precision metal mold at high speed.
- The molten metal is cooled and solidified under pressure to form a casting.
Technical characteristics of die casting:
- The metal liquid does subject to high pressure and fast flow rate during die-casting
- Good product quality, stable size, and good interchangeability;
- The production efficiency is high, and the die-casting mold is used many times;
- It is suitable for mass production with good economic benefits.
- Castings are prone to tiny pores and shrinkage porosity.
- Die-casting parts have low plasticity and are not suitable to work under impact load and vibration;
- When a high melting point alloy is die-casting, the mold life is low. which affects the expansion of die-casting production.
4. Low-pressure casting
- Melt metal into liquid at high temperature.
- Use pressure to fill the liquid metal into the mold. And the liquid metal solidifies under low pressure to form castings.
Technical characteristics of die casting:
- We can adjust the pressure and speed of liquid metal pouring. So it should apply to various casting molds (such as metal molds, sand molds, etc.), casting multiple alloys and castings of different sizes;
- The filling process of the molten metal is smooth, without splashing, and can avoid getting involved in gas. Improve the qualification rate of castings;
- The casting crystallizes under pressure, the structure of the casting is dense, the outline is clear, and the surface is smooth.
- The metal utilization rate in the casting process is increased to 90-98%;
- Low labor intensity and simple equipment, easy to realize mechanization and automation。
- Pour molten metal into a rotating mold.
- Fill the mold under the action of centrifugal force to solidify and form.
Technical characteristics of Centrifugal casting:
- There is almost no metal consumption in the metal casting process, which improves the process yield and reduces waste;
- We do not need models when producing hollow castings. Therefore, should improve the metal filling capacity in the case of long tubular castings;
The casting has a high density and almost no defects. Such as pores and slag inclusions, and their mechanical properties are increased.
- It is convenient to manufacture barrel and sleeve composite metal castings.
- There are certain limitations when we use in the production of special-shaped castings;
- The diameter of the inner hole of the casting is not accurate, the surface of the internal hole is relatively rough, the quality is poor, and the machining allowance is large;
- Castings are prone to segregation of specific gravity.
6．Gravity die casting
- The liquid metal does fill with the metal mold under the action of gravity.
- The liquid metal cools and solidifies in the casting model to form cast parts.
Technical characteristics of Gravity die casting:
- The thermal conductivity and heat capacity of metal castings are large, and the cooling rate is fast.
- Castings with higher dimensional accuracy and lower surface roughness values
can be obtained, and the quality stability is good.
- No gravel do use in the casting process. It can improve the environment, reduce dust and harmful gases, and reduce labor intensity.
- The metal mold itself has no air permeability and must take specific measures to export the air in the cavity and the gas generated by the sand core;
- It has no retreat, and the casting can prone to cracks when it solidifies;
- The metal mold has a long manufacturing cycle and higher cost. Therefore, only in mass production, it can show good economic effects.
7 . Lost foam casting
- First, the wax or foam models of similar casting sizes and shapes are bonded and combined into a model.
- After brushing and drying the refractory pain, bury it in dry quartz sand and vibrate the shape.
- Pouring liquid metal under negative pressure to vaporize the model. The liquid metal occupies the model’s position and forms a new casting method after solidification and cooling.
Technical characteristics of Lost foam casting:
- 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.
8.Vacuum die casting
In the die-casting process, the gas in the cavity of the die-casting mold is extracted. Advanced die-casting technology can eliminate or reduce pores and dissolved gases in die-casting parts. This can improve the mechanical properties and surface quality of die-cast parts.
Technical characteristics of vacuum die casting:
- 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;
- To reduce the backpressure of the cavity, can use lower specific pressure and alloys with poor casting properties, and it is possible to die-cast larger castings with a small machine;
- The filling conditions are improved, and thinner castings can be die-casted;
- The mold sealing structure can complicate. And it is difficult to manufacture and install, so the cost is high;
- If the vacuum die-casting method does improperly control, the effect is not very significant.
9．Squeezing die casting
- Liquid or semi-solid metal is solidified and flow-formed under high pressure to directly obtain parts or blanks.
Technical characteristics of Squeezing die casting:
- It can eliminate internal defects such as pores, shrinkage holes, and shrinkage porosity;
- low surface roughness and high dimensional accuracy;
- It can prevent casting cracks;
- It is easy to realize mechanization and automation.
- The advantages of the high utilization rate of liquid metal, simplified process, and stable quality, etc., are energy-saving metal forming technology with potential application prospects.