Steel Investment Casting Vs Sand Casting Process

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Steel Investment Casting Vs Sand Casting Process

Metal casting is a technique that has been used since 1838. The fundamental process is the same till now, but the machinery and technology used today are very advanced and improved. Depending on these technologies and machines, there are different ways to get the desired products or parts. Among all the metal casting processes, investment casting factory and sand casting are used commonly, In this article, these two processes are discussed and compared.

What Is Sand Casting Process

This process is named so because molten metal is pelted into sand-based molds for casting. Molten metal like magnesium, aluminum, steel, bronze, or iron is pelted into a mold. This mold is created by compacting sand mixed with water and clay for bonding which surrounds a model or pattern of the end product. 

The mold is split and the model or pattern is removed. These two parts of the mold are then joined back together and the cavity is filled with the metal in a molten state.  When it cools and solidifies, the mold is opened, and the part is taken out after sand removal. A number of parts can be cast together and a number of parts can also share a mold. 

A single mold is not reusable, but its making is easy. Sand can be reused a number of times. The molds used for this have two halves that are bound together for use.

What is Investment Casting Process

The investment casting process also called lost-wax casting or precision casting is a process used for shaping ceramic mold. A wax pattern is initially generated which has the same shape as the desired shape into which steel is to be cast. The wax pattern is covered with ceramic material. When the ceramic materials dry and solidify, it is inverted onto a heating source until it melts and gets separated.

 This solid shell serves as a disposable investment mold. The metal which is in the molten state is pelted into the mold and left until it dries. Finally, metal casting is broken from the used mold. 

Comparison Of Both Steel Casting Methods:

  • ​Investment casting factory is more costly than sand casting due to the complications and preparation required.
  • ​Sand casting cannot always be used as it cannot cast small and complex parts.
  • ​As the sand-casted product is achieved by splitting apart, the yielded parts have parting lines left on them. Also, the sand leaves a rough surface on the casted parts. These lines are to be removed by machining processes, which needs additional time and effort. On the other hand, investment casting foundry uses tough molds, so the yielded product has low tolerance, thin walls, and a smooth surface. The final product does not need additional finishing.
  • ​Investment casting employs liquid slurry to make molds, so casted parts can be cast to any of the desired shapes and other complex features, or shapes can be added or created. While sand cast parts have to be shaped so that they can escape the sand compaction easily with little hindrance, so it is not possible to create complicated shapes or features with sand casting. Moreover, it needs cavities to be properly shaped and fitted into the mold to make the interior of the part. Sometimes, a number of parts may be needed which is very time taking to create and securing them in the mold.
  • ​Sand casting offers an easy way to change the mold to cater to design changes by altering the core box or pattern which is often made from wood. While in investment casting, manufacturers need to alter or replace the solid pattern or make a new mold for making a new wax pattern which is a more complex and time-consuming task.

Conclusion:

In this article, a comparison of investment casting and sand casting is presented which can help to choose the method suitable for a casting project. Both have their own pros and cons. The choice of any method depends upon the specific requirement.

Read more: Reasons to Prefer Vacuum casting

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