Types of Casting

Casting has gone through a lot of changes since around 3200 BCE when Asians first discovered it. Now, a lot of work goes into getting the process right from start to finish. This article will show you some of the types of casting you could consider during construction.

What is Casting?

Casting is an integral part of construction. It is typically used to create the intricate shapes and designs used when building. It is the process where liquefied material is poured into a specially prepared mold and left to get cold and harden.

The mold usually contains the shape of the desired product. Hence, when the material cools and gets retrieved from the mold, it will be the desired shape that will be left. It is this solidified part that is known as a casting.

What is the necessity of casting? Casting is important because it helps create complex parts that would be quite expensive to create through any other means. Casting is often done in bulk, which helps reduce how expensive it could be producing the materials singly.

Additionally, casting provides an easy alternative during construction. Complex equipment like ships’ propellers demands a lot of work to create. Casting, again through mass production, breaks down the process.

The Different Types of Casting

Casting exists in various forms. The one you settle for depends on the need you have at that moment. Also, the materials you have available could influence the choice of casting you opt for.

Below there is a list of some of the most popular types of castings you could consider.

Sand Casting

This is the most popular type of casting. Casting sand involves packing finely ground grains together in a mold. Sometimes, clay can be added to help with adhesiveness and improve the final output’s surface finish.

Sand casting is typically used when producing engine blocks.

Sand casting involves several very important stages. The first is the patternmaking stage, followed by molding, melting, pouring and finally, cleaning. There are two patterns forms that the sand is packed in: cope and the drag.

The sand is left to get compact enough to form the desired pattern. After this, you remove the cope and extract the now-formed pattern. You will have to clean it of any risers and any adhered sand that may have gotten involved during the process.

Advantages

  • Sand casting is a relatively inexpensive process. This is especially the case when compared against the others.
  • It gives you the ability to create large components within the shortest possible time.
  • You can create both ferrous and non-ferrous materials using the process. This also reduces the cost of post-casting tooling.

Disadvantages

  • Accuracy may not always be on point with sand casting.
  • The surface finish of the final product may leave much to be desired

 

Vacuum Casting

This is often explored as an alternative to sand casting. Here, you can use unbounded sand instead of bond sand during the casting process.

Some of the essential tools used in this process include a vacuum system, a flask, a pattern, a film heater, and a vibration surface. The process is quite clean, and no wastes are produced as a result. In fact, even the dry sand is recycled for subsequent use. This makes vacuum casting one of the most environmentally friendly of all.

The first step is to place the pattern on boards that have vacuum chamber vents. You heat up the plastics and then place over the patterns. You then activate the vacuums. The plastic wraps around the pattern, so you’d have to detach them when the pattern cools.

Advantages

  • It is an alternative to sand casting
  • It is very environmentally friendly

Disadvantages

  • The casting process is a little complicated than the average

 

Plaster Casting

This casting process makes use of gypsum, strengthening compounds, and water. However, it is quite similar to sand casting, except that a crucial component, sand, is missing. To prevent the plaster from sticking to the mold, you have to coat it with an anti-adhesive compound.

Advantages

  • The process results in a very smooth finish.
  • You also obtain a higher level of dimensional accuracy than with other methods, especially sand casting.

Disadvantages

  • The process requires consistent replacement of the plaster molds, which may be expensive.

 

Investment Casting

This is also called lost-wax casting. This is because you will need to use a disposable wax pattern throughout the process.

You will have to inject the wax into a mold and afterward coat with a refractory material. This takes several stages to create a thick shell. Once the shells harden, you will then have to heat them to melt out the wax, leaving the shells behind.

The next step is to pour molten metal into the shells. The metal would harden into the shape created by the wax. You then have to break the shells to reveal the casting.

Advantages

  • The results are often very precise, leaving room for no errors
  • You can make use of this process to cast both ferrous and non-ferrous materials.

Disadvantages

  • Expectedly, this process is more expensive than the others.

 

How to Select the Right Casting Process

There are quite a number of casting options available. Here are three things to bear in mind before selecting any:

1. Complexity

The complexity of the desired product should inform your decision. This is because the different methods have their strengths and weaknesses as relates to producing complex products. Choosing the wrong process could mar the beauty of the output.

2. Cost of Casting

Casting could involve a lot of money. Plan carefully, pay attention to your budget before selecting any process.

3. Materials

It would be best if you kept an eye on the materials you have and the materials that could be used in that casting process. For example, you can use both ferrous and non-ferrous materials in sand casting.

Conclusion

This article shows you the different types of casting and the advantages and disadvantages of each. This would most likely be helpful when you are looking to make a decision one way or another.

 

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