Casting Knowledge - 25 Casting Forming Techniques! (Let more people understand casting)
Jun 04, 2026
1. Die Casting
(Note that die casting is not an abbreviation for pressure casting) is a metal casting process characterized by applying high pressure to molten metal using a mold cavity. The mold is usually made of a higher-strength alloy, and the process is somewhat similar to injection molding.
2. Sand Casting
This involves creating a mold using sand. Sand casting requires placing a finished part model or wooden model (pattern) in sand, then filling the pattern with sand. After removing the pattern, the sand forms a mold. To remove the pattern before pouring the metal, the mold should be made in two or more parts; during mold making, holes for pouring metal into the mold and venting holes must be provided to form a gating system. After the molten metal is poured into the mold, it is held for an appropriate time until the metal solidifies. After the part is removed, the mold is destroyed, so a new mold must be made for each casting.
3. Investment Casting
Also known as lost-wax casting, this includes processes such as wax pressing, wax repair, tree assembly, slurry application, wax melting, pouring molten metal, and post-processing. Lost-wax casting involves creating a wax model of the part to be cast, then coating the wax model with clay slurry to form a clay model. After the clay model dries, it is fired to create a ceramic mold. Upon firing, the wax model melts and flows away, leaving only the ceramic mold. A pouring gate is usually left during the clay mold making process; molten metal is then poured through the gate, and after cooling, the desired part is formed.
4. Die Forging
Die forging is a forging method that uses dies on specialized die forging equipment to shape a blank into a forging. Depending on the equipment, die forging is divided into hammer die forging, crank press die forging, flat forging press die forging, friction press die forging, etc. Roll forging is a plastic forming process in which material undergoes plastic deformation under the action of a pair of counter-rotating dies to obtain the desired forging or blank. It is a special form of forming rolling (longitudinal rolling).
Forging is a processing method that uses forging machinery to apply pressure to a metal billet, causing it to undergo plastic deformation to obtain forgings with specific mechanical properties, shapes, and dimensions. It is one of the two major components of forging and stamping (forging and stamping). Forging can eliminate defects such as casting porosity generated during the smelting process, optimize the microstructure, and, because it preserves the complete metal flow lines, the mechanical properties of forgings are generally superior to those of castings made of the same material. Important parts in related machinery that bear high loads and operate under harsh conditions are mostly forgings, except for simpler shapes that can be made from rolled plates, profiles, or welded parts.
5. Rolling
Also known as rolling milling, this refers to the process of shaping a metal ingot by passing it through a pair of rollers. If the temperature of the metal exceeds its recrystallization temperature during rolling, the process is called "hot rolling"; otherwise, it is called "cold rolling." Rolling is the most commonly used method in metal processing.
6. Pressure Casting
Essentially, this method involves filling a die-casting mold (die-casting mold) with liquid or semi-liquid metal at high speed under high pressure, and then solidifying it under pressure to obtain a casting.
7. Low-Pressure Casting
This casting method involves filling a mold with liquid metal under low-pressure gas and solidifying it into a casting. Initially used primarily for aluminum alloy castings, its applications have expanded to include the production of high-melting-point copper, iron, and steel castings.
8. Centrifugal Casting
This technique and method involves injecting liquid metal into a high-speed rotating mold, allowing the molten metal to fill the mold and form a casting under centrifugal force. The molds used in centrifugal casting vary depending on the shape, size, and production volume of the casting. These can be non-metallic molds (such as sand molds, shell molds, or investment shell molds), metallic molds, or metal molds lined with a coating or resin sand layer.
9. Lost Foam Casting
This is a new casting method that involves bonding and assembling paraffin or foam models similar in size and shape to the casting into a model cluster. After coating with refractory material and drying, the cluster is embedded in dry silica sand and vibrated to create the model. Under negative pressure, the metal is poured in, causing the model to vaporize and the liquid metal to occupy the model's position. After solidification and cooling, the casting is formed. Lost foam casting is a near-zero allowance, precise forming process. It eliminates the need for mold removal, parting lines, and sand cores, resulting in castings without flash, burrs, or draft angles, and reducing dimensional errors caused by core assembly.
10. Extrusion Casting
Also known as liquid forging, this method involves directly injecting molten metal or semi-solid alloy into an open mold, then closing the mold to create a filling flow that reaches the external shape of the part. High pressure is then applied, causing plastic deformation of the solidified metal (outer shell), while the unsolidified metal undergoes isostatic pressure and high-pressure solidification, ultimately obtaining the part or blank. This is direct extrusion casting. Indirect extrusion casting involves injecting molten metal or semi-solid alloy through a punch into a closed mold cavity and applying high pressure, causing it to crystallize and solidify under pressure, ultimately obtaining the part or blank.
11. Continuous Casting
This method uses a continuous crystallizer, continuously pouring molten metal into one end and continuously pulling out the shaped material from the other end.
12. Drawing
This is a plastic forming method that uses external force applied to the front end of the metal to draw a metal billet through a die hole smaller than the billet's cross-section, obtaining a product of the corresponding shape and size. Because drawing is mostly performed in a cold state, it is also called cold drawing or cold stretching.
13. Stamping
Stamping is a forming process that uses a press and dies to apply external force to sheet metal, strip, tube, and profiles, causing plastic deformation or separation to obtain workpieces (stamped parts) of the desired shape and size.
14. Metal Injection Molding
Metal injection molding is a new type of near-net-shape powder metallurgy forming technology derived from the plastic injection molding industry. It is well known that plastic injection molding technology produces various complex shapes at a low cost, but plastic products have low strength. To improve their performance, metal or ceramic powders can be added to the plastic to obtain products with higher strength and better wear resistance. In recent years, this idea has evolved to maximize the content of solid particles and completely remove the binder and densify the formed blank during the subsequent sintering process. This new powder metallurgy forming method is called metal injection molding.
15. Turning
Turning on a lathe is a part of machining. Turning on a lathe mainly uses a cutting tool to turn rotating workpieces. Lathes are primarily used for machining shafts, discs, sleeves, and other workpieces with rotating surfaces. They are the most widely used type of machine tool in machinery manufacturing and repair shops. Turning is a machining method that utilizes the rotation of the workpiece relative to the cutting tool on a lathe to cut the workpiece. The cutting energy in turning is mainly provided by the workpiece, not the cutting tool. Turning is the most basic and common cutting method, playing a vital role in production. Turning is suitable for machining rotating surfaces; most workpieces with rotating surfaces can be machined by turning, such as internal and external cylindrical surfaces, internal and external conical surfaces, end faces, grooves, threads, and surfaces of revolution. The cutting tool used is primarily a lathe tool.
16. Milling
Milling involves fixing the workpiece and using a high-speed rotating milling cutter to cut out the desired shape and features. Traditional milling is mostly used for milling simple shapes/features such as contours and grooves. CNC milling machines can machine complex shapes and features. Milling and boring machining centers can perform three-axis or multi-axis milling and boring operations, used for machining molds, gauges, fixtures, thin-walled complex curved surfaces, artificial prostheses, blades, etc. When selecting CNC milling machining operations, the advantages and key roles of CNC milling machines should be fully utilized.
17. Planing
Planking is a cutting method that uses a planer to perform horizontal, relative linear reciprocating motion on the workpiece. It is mainly used for machining the shape of parts. The accuracy of planing is IT9~IT7, and the surface roughness Ra is 6.3~1.6um.
18. Grinding
Grinding is a machining method that uses abrasives or grinding wheels to remove excess material from a workpiece. Grinding is one of the most widely used cutting methods.
19. Selective Laser Melting
In a tank filled with metal powder, a computer-controlled high-power carbon dioxide laser selectively sweeps across the surface of the metal powder. Where the laser reaches, the surface metal powder completely melts and bonds together, while areas not touched remain in a powder state. The entire process must be carried out in a sealed chamber filled with inert gas.
20. Selective Laser Sintering (SLS)
SLS uses an infrared laser as its energy source and primarily employs powder materials. During processing, the powder is first preheated to a temperature slightly below its melting point, then spread evenly using a leveling roller. Under computer control, the laser beam selectively sinterstens based on the layer cross-sectional information, layer by layer, until all layers are sintered. Excess powder is removed after sintering, resulting in a sintered part. Currently, wax powder and plastic powder are mature materials for this process; processes using metal or ceramic powders are still under research.
21. Metal Deposition
Similar to fused deposition modeling (FDM), but instead of spewing out powder, metal powder is ejected. The nozzle simultaneously ejects the metal powder material and provides a high-power laser and inert gas protection. This avoids the limitations of the powder chamber size, allowing for the direct fabrication of larger parts, and is also suitable for repairing locally damaged precision parts.
22. Roll Forming
Roll forming uses a series of continuous stands to roll stainless steel into complex shapes. The roll sequence is designed so that the rolls in each stand continuously deform the metal until the desired final shape is achieved. For complex parts, up to thirty-six stands may be needed, while simpler parts can be formed with only three or four stands.
23. Die Forging
Die forging is a forging method that uses dies to form blanks on specialized die forging equipment to obtain forgings. This method produces forgings with precise dimensions, small machining allowances, and relatively complex structures, resulting in high productivity.
24. Die Cutting
Die cutting is the blanking process where the pre-formed film is positioned on a die, the die is closed to remove excess material, preserving the product's 3D shape and matching the die cavity.
25. Die Cutting Process - Cutting Die
Die cutting is the blanking process where the film panel or circuit is positioned on a base plate, the cutting die is fixed to a template on the machine, and the downward pressure from the machine controls the cutting edge to cut the material. What distinguishes it from punching dies is that it produces a smoother cut; at the same time, by adjusting the cutting pressure and depth, it can punch out effects such as indentations and partial breaks. In addition, the die is low in cost and the operation is more convenient, safe and fast.
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