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Investment Casting Material Options

Investment casting is such a versatile manufacturing solution in part because the material options are nearly endless.

Whether you’re looking for corrosion resistance, increased tensile strength, or ductility, we have the materials to meet your requirements. At Signicast, we pour everything from 400 series stainless steel and plain carbon steel, to nickel and aluminum. With the capability to cast parts ranging from a few ounces to upwards of 200 pounds, Signicast’s investment casting process is one of the most dynamic manufacturing solutions on the market.

This versatility means that we can more easily resolve traditional casting challenges in design, production, cost control, and delivery. The availability of material options means that you don’t necessarily have to sacrifice one element of a design in favor of lowering cost—our engineers are involved in every step of the design and production process to aid in the selection of the most effective metal for your project’s unique challenges.

 There are a lot of factors to take into consideration when selecting the best alloy for the job. To narrow the scope, here are some frequently asked questions about investment casting materials and options, answered.

What alloys accept plating or painting best?

Any material can be painted. The alloys that are easiest to paint are generally those that don’t oxidize a lot. For instance, stainless steels can be difficult to paint without some secondary thermal processes, but the plain carbon low alloy steels are quite easy to paint. The other factor that affects painting and plating is the surface finish of each unique part. If the part is too smooth, the paint won’t adhere as well. In general, low alloy steels paint and plate the best.

Does Signicast refine carbon and low alloy steels?

Typically, we don’t need to refine these materials. Our proprietary process meets and exceeds clarity properties without any subsequent steps. We melt very clean raw materials, as opposed to other processes like sand casting that need to refine their melts to eliminate unwanted matter.

Can you create identical parts of different alloys from the same tool or do you need one tool per each alloy of identical parts?

Due to the different coefficient of thermal expansion of each alloy, a tool that accommodates the shrink rate of one alloy may not be able to accommodate the shrink rate of another. Though the wax pattern would be the same dimension regardless of the alloy, the part will shrink differently during and after solidification with different metals.

Are some alloys better than others for minimizing porosity?

Some alloys are better for minimizing porosity without secondary operations, but minimal porosity can always be achieved with additional heating processes. For instance, aluminum alloys can be quite difficult to manufacture without secondary shrinkage operations. Due to its high hydrogen solubility, bubbles can form as the part solidifies, so there must be extra processing steps to prevent that from affecting the performance and porosity of the final product. Generally speaking, stainless steels are good for minimizing porosity during initial production.

What alloy works best for thin walls?

Because we spend a lot of time designing each casting, we can achieve very thin walls with most materials. Aluminum works quite well for thin-walled parts, as well as sulfur-baring steels.

If you’d like to learn more about the benefits of the wide spectrum of material options, download our free, on-demand seminar on investment casting materials here.

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Last updated 11.27.2019