5 Steps in the Die Casting Process

The die casting process is a common process for batch metal processing, and if you're new to the die casting industry, you may think that gravity die casting is a highly technical and complex process, but in reality, it's actually quite simple. It may be helpful to think of it as a conversion method or a way of turning one thing into another; that is, transforming molten liquid metal (such as aluminum or zinc) into a cast metal part or assembly. This conversion is permanent and can be broken down into a few easy-to-understand steps.

In the following, we'll go over each step in detail, explain exactly how the gravity die casting process works, and outline what types of products it can be used to make.

Gravity Die Casting Step-by-Step Guide
Step 1: Preparation
The first step before the gravity casting process begins is to prepare the mold itself. Essentially, this involves heating it to the right temperature and spraying it with a refractory coating or lubricant. This lubricant not only keeps the mold warm during the manufacturing process, but it also prevents premature solidification and aids in the removal of the casting once it has solidified.
High pressure can then be used to close and clamp the half molds together tightly.

Step 2: Injection
After this preparation stage, the molten metal is removed from the furnace and the ladle is poured directly into the mold via a downward-facing sprue. This can be done manually or, in some cases, using an automated ladle; but either way, the process utilizes gravity. No additional force or pressure is applied. The molten liquid is simply inserted into the mold from an upright, vertical position, and due to natural gravity, it will work its way down into the casting on its own.
By avoiding the use of high pressure, turbulence is significantly reduced, which in turn helps prevent porosity and leads to the production of smoother components and parts.

Step 3: Cooling
After injecting the molten metal into the casting, it is cooled and solidified. The metal should be given enough time to form the shape of the mold and needs to be fully solidified before the mold is released. Removing the plaster too soon may result in irreversible defects.

Step 4: Ejection
After a sufficient amount of time has elapsed, loosen and open the half-mold and carefully remove the cast. This can be done by hand or, in some cases, using an ejector bar to safely push the casting out of the gravity die casting machine.

Step 5: Trimming
The final stage of the gravity casting process is trimming. As the metal continues to cool, any scrap metal (including gates, runners, sprue and fretting) is skillfully removed from the casting. Any sharp edges and excess material are removed using a variety of tools to create the desired shape of the part, and the part is usually cleaned before it is sent to the customer.