Beginner’s Guide to Permanent Mold Casting Process

Permanent mold casting refers to a metal casting process that utilizes reusable molds that we make from metal. We commonly refer to the permanent mold casting process as the gravity die casting process since the molten metal naturally flows into the die under the influence of gravity. It shares similarities with die casting and sandblasting, which both involve pouring of molten metal into molds. However, it holds certain advantages over them that we shall cover later on.

 

There are essentially 6 distinct steps to the process.

• Preparation of the Mold

We preheat the casting mold to between to 150 degrees Celsius and 260 degrees Celsius. This enables better metal flow while at the same time decreasing the defects that are likely to arise during the casting process.

• Assembly of the Mold

After preheating the mold, we apply a ceramic coating to the mold’s cavity. This allows easier part removal, which comes in handy in prolonging the mold’s life cycle. Typically, the mold that is in use comprises two halves that may have cores to facilitate more complex castings. We make our cores using iron or steel. In some instances, we use expendable sand cores.

• Pouring

We then pour molten metal into the mold at a slow rate. We perform this from a ladle into the mold through a sprue. The poured molten metal now flows through the entire runner system into the mold, which in the process fills the cavities.

• Cooling

We subject the molten metal to cooling to enable solidification into the desired mold shape, make final product feature and more quickly production process.

• Opening of the Mold

Upon cooling and solidification, we open the two mold halves and remove the casting.

• Trimming

It is a process that involves removing the excess material from the casting. We refer to these materials as solidified sprues and runners. We have removed some of the shape, polish surface, drilling hole and more after-finishing process to complete better products.

 

Evolution of the Permanent Mold Casting Process

Over the years, Creatingway has gone through various variations and evolutions of this process. It has been in a bid to accommodate very specific applications. Some of these evolutions include:

• Low-pressure permanent molding

In this process, instead of pouring the molten metal, we force it into the mold using air under low pressure. It allows the mold to remain filled and assists in reducing shrinkage that arises during the cooling process. This technique allows for thinner cast walls and molding of finer details.

• Vacuum Permanent Mold Casting

It involves applying vacuum pressure to fill the mold. Like the low-pressure technique above, it allows for finer details, thinner walls, and better properties mechanically.

• Slush Casting

In the conventional technique, we pour the molten metal into the mold, then allow it to cool and solidify at the cavity’s surface. When the solidified amount is equal to the desired wall thickness, we pour the material that is yet to solidify out of the mold. This is a technique we mainly use to cast hollow parts without using cores.

 

Surface Finishes and Treatments for Permanent Mold Casting

As a premium permanent mold casting provider, Creatingway offers several surface finishes, secondary operations, and treatment for the cast parts, including:

• Anodizing process

It entails creating an anodic film that increases the part’s resistance to corrosion and abrasion. It also produces an aesthetically pleasing finish that is not subject to fading.

• Plating process

We perform chrome, zinc, and nickel plating on permanent cast parts. We utilize zinc more since it is inexpensive and offers resistance to corrosion to protect products surface.

• Impregnation

It is a process that applies a sealing medium to deal with the issue of porosity. Which is suitable to the holes of more precision parts, shaft surface and gear holes.

• Polishing

We perform it on aluminum casts to impart a better finish. Also, we can complete it with mirror-like polishing as customers’ expected. Currently, we have been served to most of industries like electronic device, mechanical, medical device, aerospace and more.

 

Parameters that we consider in determining the casting process to use.

• Cost per part
• Cost of tooling
• The strength and soundness the client’s needs
• The level of smoothness and amount of wall thickness the client specifies
• The design and shape of the part.

 

Advantages of Permanent Mold Casting

• Its core advantage is the ability to re-use the molds
• We can use the process to produce more complex designs and shapes than sand casting
• The casted part has excellent finish than sand cast parts.
• It allows for more accurate control over dimensional aspects than sand casting
• The permanent mold cast part has excellent mechanical properties, minimal shrinkage, and low gas porosity
• The process produces little scrap and the parts have a uniform grain structure.

 

Limitations to Permanent Mold Casting

• Materials with lower melting temperatures are the only ones in use in the process
• Though we cast iron using this process, the high melting point of cast iron has a wearing effect of the mold in use.
• As the mold requires opening and closing, we often have to limit the geometry of its parts.
• It often requires a long time to set-up with an equally higher tooling cost.

 

Uses of Permanent Cast Molding

We use permanent cast molding to produce parts requiring greater strength and durability. A few of its applications include:

• Brake castings
• Pump components
• HVAC and ventilation parts including fan blades and blowers
• Electronic Housings
• Manifolds
• Valve Bodies

 

Creatingway is capable of deftly delivering aluminum, copper, and magnesium permanent mold casting services. However, all castings are top-notch and meet world-class standards. Furthermore, we achieve this through our able team of experts. Simply contact us with any of your inquiries.

 

Creatingway is concentrated on CNC machining manufacturing, prototype machining, low-volume manufacturing, metal fabrication and parts finishing services, provide you the best support and services. ask us one inquire now.

 

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