Casting process

Casting processes are manufacturing processes and process variants for casting metals. For the pouring of food see Mogultechnik , for the pouring of concrete and ceramics see there. For the processing of polymer concrete, see mineral casting . Casting in dentistry is described under investment material . For the preparation and post-processing of casting (mold making, melting of metals, etc.) see casting (metal) .

There are numerous different casting processes that can be classified according to several criteria.

Classification according to the shape of the workpieces

• Mold casting is casting in molds that largely correspond to the shape of the finished part, which is used in foundries .
• Ingot casting , the casting into bars or slabs, which are further processed by forming ( forging , rolling ) or machining ( milling , drilling ).
• Continuous casting , the casting of continuous, theoretically endless strands. Mainly used in steel works and smelting works (for non-ferrous metals ).
  • Endless strip production for the production of steel strips, with combined subsequent rolling
  • Castrip also for the production of steel belts

Type of mold filling

A distinction is made according to the type of mold filling

• Gravity casting , the standard process in which the melt falls into the mold by the action of gravity, as well as that
• Centrifugal casting and that
• Die casting , in which the melt is pressed into the mold by piston pressure.

A distinction is also made between whether the melt falls directly into the mold or is fed in via side accesses ( gate ). The tiltabe casting combines the advantages of these variants.

Classification according to the type of shapes and models

A particularly important division distinguishes between processes with molds that are only used once and are destroyed when the castings are removed ( lost mold ) and permanent molds that are used multiple times.

Casting with lost forms

Models are used to manufacture the molds. A further distinction is made as to whether the models can be used once ( lost model ) or several times ( permanent model ) .

• Casting with lost molds and permanent models: It is also known as sand casting because the molds are made from sand. Depending on the type of mold production, it is suitable for individual parts and series pieces as well as any workpiece dimensions and is therefore of great economic importance. Numerous vehicle components are manufactured in this way. Since sand is very temperature-resistant, it is mainly used for pouring cast iron and cast steel.
  

  Die casting according to the cold chamber process (used for aluminum)
  • One variant of the process is low-pressure sand casting .
  • The further classification is based on the type of mold production:
    • Compaction molding process
      • Stamp molding process
      • Vibrating , pressing , high pressure pressing
      • Blowing , shooting and high pressure pressing
      • Vacuum precompression and high pressure pressing
      • Air flow method
      • Air pulse method
    • Solidification molding process
      • Mask molding process
      • Cement sand molding process
      • Water glass carbon dioxide process
      • Phenolic resin hardener process
      • Vacuum forming process
• Casting with lost molds and lost models:
  • Lost wax casting ( investment casting ) In investment casting, the models are made of wax and covered with clay or ceramic. Then the wax is melted out and the mold is filled with melt. It is only suitable for smaller quantities and small workpiece dimensions, but achieves high quality.
  • Full mold casting . With full mold casting, the models are built from Styrofoam, surrounded with any molding material and then, without removing the models, poured over melt that burns the models. It is suitable for small quantities and also very large castings.
  • Lost foam . The process is similar to full mold casting, but the molds are made of loose sand.

Casting with permanent molds

When casting with permanent molds, the molds can be used multiple times. They are mostly made of steel (mostly hot-work steel ) and some of ceramic or graphite . When they come into contact with the melt, they wear out, which means that the workpieces have a poorer surface quality and shape accuracy than lost shapes. In the case of low-melting materials such as aluminum, they can be poured very often, but less often in the case of high-melting materials such as copper. Since the permanent forms are very expensive, the number of pieces has a strong effect on the unit price.

• Chill casting : gravity casting with permanent molds
• Die casting : Here the melt is pressed into the mold by means of a piston. The time to fill the mold is reduced, which is why it is well suited for large series of small workpieces. It is particularly often used for casting aluminum, the
  • Die-cast aluminum .
  • Magnesium die casting .
  • Squeeze casting
  • Thixocast
  • Vacuum pressure casting
• Centrifugal casting
  

  Variants of centrifugal casting
• Continuous casting
• Low pressure casting : Here, the air pressure around the melt is increased in order to force it into a riser pipe that leads to the mold.
• Vacuum casting

Classification according to the material used

Cast iron and cast steel are usually made by sand casting , as the sand molds can withstand the high temperatures of the melt. Otherwise there is still that

• Aluminum die casting , a variant of die casting , for aluminum casting alloys . About 80% of the aluminum processed in the foundry is cast using this process.
• Cobapress , also for aluminum parts, is a process combination of casting (French: couler) and pressing .
• Magnesium die casting
• Bronze casting , is mainly used in arts and crafts ( art casting )
• Alfer process . Here, aluminum (Al) is used to cast a workpiece made of iron (Latin: ferrumfer).
• Zinc die cast
• Thixocasting . Here a material is cast (English casting), which is in the thixotropic state. It is partly solid and partly liquid and completely liquefies under the action of pressure. After releasing the pressure, it freezes again very quickly.

Special procedure

There are also a number of special processes such as Thixocasting , Vacuralgießen , Gradientenguss , the African brass , the stack casting , the composite casting and squeeze casting . Especially in the crafts is Kunstguss used.

See also

• List of machining processes
• Joining process
• Forming process

Individual evidence

1. ^ ^{A b c d} Engelbert Westkämper, Hans-Jürgen Warnecke : Introduction to manufacturing technology , Vieweg-Teubner, 8th edition, pp. 78–92.
2. ↑ Fritz Klocke: Manufacturing Process 5 - Gießen, Powder Metallurgy, Additive Manufacturing , 4th Edition, Springer, 2015, p. 4.
3. ↑ Rüdiger Bähr , Stefan Scharf: Cast part production with lost forms in: Andreas Bühring-Polaczek , Walter Michaeli , Günter Spur (eds.): Handbuch Urformen , Hanser, 2014. P. 181.
4. ^ Fritz Klocke: Manufacturing process 5 - Gießen, powder metallurgy, Additive Manufacturing , 4th edition, Springer, 2015, p. 20.