Casting mold:

 

Overview of the world's top ten casting processes

Sand casting: suitable for blanks with complex shapes and complex inner cavities, low cost and strong adaptability.

 

Sand casting: a casting method for producing castings in sand molds. Steel, iron and most non-ferrous alloy castings can be obtained by sand casting.
Process flow:

 

Technical features of sand casting process flow: 1. Suitable for making blanks with complex shapes, especially those with complex inner cavities; 2. Wide adaptability and low cost; 3. For some materials with poor plasticity, such as cast iron, sand casting is the only forming process for manufacturing its parts or blanks.
Application: Automobile engine cylinder block, cylinder head, crankshaft and other castings

 

 

Sand casting mold gold mold

 

 

Sand casting product display

 

Investment casting: usually refers to a casting method in which a pattern is made of fusible material, several layers of refractory material are coated on the surface of pattern to form a shell, then pattern is melted and discharged from shell to obtain a casting without a parting surface. After high-temperature roasting, sand can be filled and poured. It is often called "lost wax casting".
Investment casting is one of the most complex casting processes. While forming a complex structure of parts, it can also achieve high dimensional accuracy and surface quality. Investment casting can be used to produce almost all metal products to meet needs of a wide range of terminal markets. Investment casting is a metal forming process. A ceramic heat-resistant material is coated on the surface of a wax mold to form a ceramic mold. Formed ceramic mold is dried, melted, and wax mold is removed to form a shell. Then, molten metal is poured into ceramic mold shell, and mold shell is removed after metal is formed to obtain casting. Some investment castings need to be processed after casting. Investment casting process is usually used to produce parts with complex shapes and high requirements for dimensional accuracy and surface quality.
Investment casting is also called lost wax casting, which includes processes such as wax pressing, wax repairing, tree assembly, slurry dipping, wax melting, casting molten metal and post-processing. Lost wax casting is to use wax to make a wax mold of part to be cast, then apply mud on wax mold, which is mud mold. After mud mold is dried, it is placed in hot water to melt internal wax mold. Mud mold with melted wax mold is taken out and baked into a ceramic mold. Once roasted, a pouring port is usually left when making a clay mold. Then, molten metal is poured in from pouring port. After cooling, required parts are made.
Since pattern is widely made of wax material, investment casting is often called "lost wax casting". Types of alloys that can be produced by investment casting include carbon steel, alloy steel, heat-resistant alloy, stainless steel, precision alloy, permanent magnetic alloy, bearing alloy, copper alloy, aluminum alloy, titanium alloy and ductile iron. Shape of investment castings is generally more complex, minimum diameter of hole that can be cast on casting can reach 0.5mm, and minimum wall thickness of casting is 0.3mm. In production, some parts that were originally composed of several parts can be designed as integral parts by changing structure of parts and cast directly by investment casting, so as to save processing time and metal material consumption, make part structure more reasonable. Weight of investment castings is mostly from zero to dozens of Newtons (from a few grams to more than ten kilograms, generally not more than 25 kilograms). It is more troublesome to produce too heavy castings by investment casting. Process of investment casting is more complicated and difficult to control, materials used and consumed are more expensive. Therefore, it is suitable for production of small parts with complex shapes, high precision requirements, or difficult to perform other processing, such as turbine engine blades. It can meet requirements of various material specifications such as ASTM, SAE, AISI, ACI, DIN, EN, ISO and GB, has casting capacity to produce hundreds of black and non-ferrous alloy materials including stainless steel, alloy steel, copper alloy, aluminum alloy, high temperature alloy, carbon steel, cast iron, etc.
Process flow:

 

 

Precision casting mold wax injection wax injection

Tree formation

Automatic line shell making
Investment casting process is also called "lost wax casting". According to product requirements of customers, mold is designed and processed, wax material is pressed into mold to form a product wax mold, it is bonded with pouring cup and runner wax mold to form a wax tree. After coating surface of wax tree with multiple layers of refractory slurry and sand, shell is made, wax material in shell is heated and melted out. Then molten metal is poured into shell that has been roasted at high temperature. After molten metal solidifies and cools, it is cut, cleaned and other post-processing methods are used to finally obtain required casting. Compared with other casting processes: it is applicable to a wide range of materials, structure of cast products is complex, surface roughness is high, and dimensional accuracy is high. It can be processed without or very little processing. It is an advanced process for near-net forming.
Process characteristics
Advantages: 1. High dimensional accuracy and geometric accuracy; 2. High surface roughness; 3. Ability to cast castings with complex shapes, and alloys cast are not restricted.
Disadvantages: Complex processes and high costs
Application: Suitable for production of small parts with complex shapes, high precision requirements, or difficult to perform other processing, such as turbine engine blades.
Typical investment castings produced using 3D technology

 

In investment casting production, shell making process is an important part of whether product casting can be successful. Only by mastering key technologies and control capabilities of shell making process can highly difficult products be made. Investment casting shell making process is achieved by repeating process of "coating-sanding-drying". For castings with slender holes and narrow grooves, it is difficult to coat densely during coating, and shell strength is insufficient, resulting in defects such as fire, bulging, peeling, shrinkage, and shrinkage. When ratio of groove depth to groove width H/d>5 times, it is extremely difficult to cast and is usually not cast.