A Guide of Die Casting

Last Updated on December 26, 2022 by Leizi

If you want to make high-volume metal parts with high quality and durability, one of the best choices for you is die casting.

If you already know the basics about die casting, you may have noticed the similarities between die casting and injection molding—By transforming molten liquid material into custom parts.

But compared with injection molding, die casting is a more complicated technique. This article will offer a brief guide on the types, processing steps, limitations, and defects of die casting.

Die Casting

1. What are the two types of die casting?

The most common casting techniques include cold and hot chamber die casting.

Advantages of cold chamber die casting:

1). It is suitable for metal casting with a higher melting point.

2). It can process multiple types of metals at the same time.

Advantages of hot chamber die casting:

1). It is suitable for metal casting with low melting points.

2). It is more cost-effective.

Hot Chamble and Cold Chamble Die Casting

2. What are the five steps in the die casting process?

The die-casting process includes five steps: clamping, injection, cooling, ejection, and trimming.

First step: Clamping

Before clamping the mold, it needs to be cleaned and lubricated. This keeps the mold warm and facilitates the removal of the solidified metal casting from the mold. After that, it can be clamped and closed with high pressure.

Second step: Injection

The next step is to melt the selected metal and pour it through the sprue into the firing chamber. Afterward, the molten metal is injected into the mold by high pressure.

Step three: Cooling

Similar to plastic injection molding, there is a waiting period until the metal has completely solidified into the shape of the mold.

Step four: Ejection

After the previous step is complete, we will open the mold halves and remove the castings.

Step five: Trimming

After the previous four steps, the casting still has excess metal in the gates and runners. The craft department uses saws or other tools to remove and trim excess metal.

Trimming for Casting

3. What are the limitations of die casting?

1). High cost. Making metal molds takes a long time, and for projects with complex designs, it can take months to design and make the molds. In addition to the time cost, if the quantity of the project is not high, the cost of making molds and raw materials will increase exponentially.

2). Materials and dimensions are limited. The most commonly used materials for die casting are aluminum, zinc, and magnesium. If it is a metal with a high melting point, it is not suitable for making castings. Also for large parts, die casting is also an unsuitable choice.

4. What are the main defects that occur during die casting?

Die-casting processing is complex, and if there is improper execution in a certain processing step, it may lead to the quality of die-casting parts. Below are the six common types of die casting defects.

  1. Stomata

During pouring, there may be entrapped gas, forming a circular cavity.

  1. Inclusions

Cleaning and lubrication are necessary steps before injecting molten metal material. If this step is skipped and the injection is performed directly, the sand or foreign matter in the mold will affect the quality of the die casting.

  1. Insufficient filling

This defect occurs due to many factors, such as insufficient injection pressure, low mold temperature, poor fluidity of molten metal, and waiting.

  1. Deformation

After the die-casting process, the formed die-casting parts are partially deformed.

  1. Shrink failure

Surface and internal shrinkage defects occur due to poorly designed gates and risers in the mold.

  1. Tortoise crack

If the material of the die-casting mold is not of high performance, or the heat treatment process is improper, these will cause cracks on the surface of the mold cavity.

If you want to know more about the die casting process, contact us now.

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