Investment Castings | What Is the Vacuum Casting Method?

Investment castings, which are often referred to as lost-wax castings, are metal parts that are produced by the investment casting process. This expendable mold process and the components that it produces is extremely popular for countless applications in numerous industries. This is largely due to the fact that the investment casting process makes it possible to create complex parts with exceptional surface qualities and accuracy in a wide range of materials and sizes. However, if a part requires intricate details or undercuts, the material is reinforced by fiber or wire, or air entrapment is a problem, a specific type of investment casting method is used. This investment casting technique is none other than the vacuum casting method, which produced vacuum castings. What are vacuum castings? Keep reading to find out.

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What Are Vacuum Investment Castings?

Vacuum castings are the metal parts that are produced by the vacuum casting method. They are different than typical investment castings due to the technique that is used to create these metal parts. The process begins by placing a two-piece mold in a vacuum chamber. The vacuum then draws the molten metal into the mold. Finally, the casting is solidified in an oven and the mold is removed in order to release the final product.If you have a project that requires high-quality vacuum investment castings, we can provide them for you. Here at Ferralloy, Inc., we utilize both gravity fed and vacuum casting methods to produce metal components that range in weight from a few ounces up to 75 pounds. Our countless years of experience in both of these methods guarantee that we can supply superior or near net shape parts that require little or no finish work. Get the investment castings that you need, delivered on time and at a competitive price, by contacting us today!

Vacuum investment casting produces metal pieces with exquisite detail and a superb surface polish. It is much more complicated than traditional investment casting exporters, necessitating specialized melting and mold-filling equipment. As a result, it is only used for casting components that require extremely high levels of structural integrity and where mistakes are costly.

Why Should You Vacuum?

Liquid metal "churns" when it pours into a mould. Turbulence causes two kinds of defects: oxides and porosity.

Metal atoms bind with oxygen to produce oxides. This occurs at the metal-air interface, when an oxide layer develops. Surface oxidation is useful on some metals, such as aluminium, since it generates a corrosion-resistant coating. However, there is a difficulty throughout the casting process.

This is because, when the liquid metal churns, oxides develop on the surface and are absorbed into the cast part's body. When the metal hardens, these discontinuities become weak points.

Filling gently from the bottom of the mould reduces turbulence, oxidation, and porosity.

The vacuum casting method is divided into five steps:

The first step in producing any vacuum cast component is to create a 3D model of the component in question. The model is created following the same design criteria as injection moulding moulds.

Before generating the 3D model, proper calculations must be performed. Deformities in the model might have an impact on the finished product after casting. As a result, it is critical to adhere to design rules and make necessary revisions to calculations.

The master pattern for the mould is developed using 3D rendering. The master pattern is the primary mould used to create the silicone moulds that will be utilized for casting. It is a prototype for silicone moulds made of high-durability materials such as metals or other polymers.

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Previously, master patterns were manufactured using CNC or hand tools, but today, technologies like as 3D printing, stereo lithography, and other similar procedures are utilized to make master patterns more cost-effective and precise.

The next stage is to create silicone moulds after creating the master pattern. The master pattern and a casting box are used to create silicone moulds directly.

Inside the casting box, the master pattern is hung. The master pattern is filled with cores and inserts. Along with the core, the casing box has casting gates and risers for pouring molten silicone and extracting the final mould.

Around the master design, hot, molten silicone is poured into the casting box.

The polyurethane (PU) resin mixture is prepared prior to casting by mixing the resin with other casting components such as pigments and other agents and heating the resin. Various polyurethanes with variable material and structural properties are available depending on the type of product to be created.

The resin mixture is created by putting the two parts of the resin in a container and heating the mixture to around 40°C. At this stage, colour pigments are also mixed. It should be observed that the resin and pigments have thoroughly mixed into a homogenous solution before pouring the resin mixture into the moulds.

The mould is placed in the vacuum casting machine for casting after the solution has been completely set in the mould and properly sealed. The temperature and duration for casting may vary depending on the type of polyurethane utilized, but the procedure stays the same.

When the casting is finished, the mould is kept in the casting machine to cure. Curing aids in the retention of structural integrity after the cast is removed from the mould.

Investment casting exporters is a very cost-effective and efficient production method. When compared to traditional technologies such as plastic injection moulding and pressure die casting, vacuum casting has a very cheap manufacturing cost.