Investment Castings

When you’re producing complex parts for sensitive applications, it’s critical to choose an investment casting manufacturer you can trust. Sinotech’s investment castings combine unparalleled quality and precision with the affordability of overseas manufacturing.

We have more than two decades of experience making QS-9000 and ISO certified investment castings in the Pacific Rim. All of our castings are produced and managed onsite at our factory in Ningbo, China – allowing us to provide high-quality steel, aluminum and other metal components at competitive prices.

When you partner with Sinotech for your investment casting needs, you’ll receive all the benefits of working with a domestic supplier. We’re an American company operating under U.S. law, and we’ve developed stringent quality control practices to ensure the finished product meets your specifications to the letter. We use Magnetic Particle Inspection to check for invisible cracks or inclusions, while our high-accuracy machining and CMM confirmation ensures your castings will be dimensionally correct.

Contact us to learn more about the benefits of choosing Sinotech as your investment casting manufacturer.


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Uses for Investment Casting

Investment casting manufacturers can achieve such high accuracy and close tolerances that the parts produced often need no further machining. We recommend investment casting for projects involving:

  • Intricate shapes requiring high accuracy. Tolerances of 0.5% of length are routinely possible; for small dimensions, 0.15% is possible.
  • Metals that are difficult to machine or fabricate. Materials suitable for casting include aluminum alloys, bronzes, tool steels, stainless steels, Stellite, Hastelloys and precious metals.
  • Parts that can’t be made using normal techniques. For example, investment casting is ideal for complex turbine blades and airplane components that must withstand high temperatures.
  • Safety-critical applications. Many of our investment castings are used in critical automotive applications in which metallurgy, tensile strength and malleability must be carefully controlled.

How Investment Casting Works

Also known as the “lost wax process,” investment casting is one of the oldest manufacturing techniques. Egyptians used it to make gold jewelry some 5,000 years ago, during the time of the Pharaohs. Today, steel investment casting is used to make intricate parts and machine components for a wide variety of industries.

Creating the pattern: Each casting originates from a three-dimensional solid model designed using a computer modeling program. The virtual model is then fabricated via stereo lithography, a 3D printing process, into a pattern made of wax (or another material that can be melted away).

Making the mold: The wax pattern is then dipped multiple times in refractory slurry, which forms a skin over the wax. For low-temperature melts, the slurry is typically composed of plaster of Paris, a binder; and powdered silica, a refractory. For higher-temperature melts, sillimanite (an alumina-silicate) is used as a refractory, and silica is used as a binder. Depending on the fineness of the desired finish, additional coatings of sillimanite and ethyl silicate may be applied. For heavier castings, the investment casting mold may then be placed inside a larger container and reinforced with more slurry.

Heating the mold: Next, the entire pattern is heated in an oven to melt the wax away so the mold can be filled with molten metal. Because the mold is formed around a one-piece pattern that does not have to be pulled out from the mold (as in a traditional sand casting process), highly intricate parts and undercuts can be made.

Pouring the metal: Just before the pour, the mold is pre-heated to about 1,000 degrees Celsius to remove any wax residue and harden the binder. Pre-heating also ensures that the mold will fill completely. Pouring can be done using gravity, pressure or vacuum conditions. When using pressure, attention must be paid to mold permeability in order to allow the air to escape.

Investment castings can weigh from a few grams to 35 kilograms (0.1 ounce to 80 pounds), although the normal size ranges from 200 grams to about 8 kilograms (7 ounces to 15 pounds). Normal minimum wall thicknesses for alloys that can be cast easily range from about 0.5 to 1 millimeter (0.02-0.04 inches).

Watch our video about the investment casting process:


Sinotech ensures excellent investment castings from our factory in Ningbo, China at really competitive prices. Sinotech has manufactured QS-9000 and ISO certified investment castings in China, Taiwan and Korea for over 20 years. Many of our castings are used in safety critical automotive applications where metallurgy, tensile strength and malleability must be carefully controlled. We use Magnetic Particle Inspection to assure there are no invisible cracks or inclusions.

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