A major advantage to investment castings involves the types of metals used to produce parts. Any metal that can be melted can be cast using this process. Investment casting metals come in two categories: nonferrous and ferrous metals. Selecting which metals within these two groups will be based on your application. When determining the differences between metals, the major factor depends on if there is iron present.

Iron is the Key for Ferrous Metals

Ferrous metals contain iron while non-ferrous metals do not. Due to this iron, metals possess greater levels of conductivity. The metal also possesses a good tensile strength that allows it to experience high levels of stress without breaking. Possessing this great mechanical property along with strength and durability allows customers to use ferrous metals for parts in electrical and high-stress applications.

The one thing to keep in mind is that due to possessing iron, many ferrous metals are prone to corrosion. Applications where there will be an abundance of moisture, humidity, solvents, motor oils, and other caustic substances may wear out the part until it fails. To work around this problem, ferrous metals may have additives such as chromium placed into the melt to provide better corrosion resistance. By enhancing these alloys, the manufacturer may develop investment castings that can be used in such harsh environments.

Types of ferrous metals include steel, cast iron, stainless steel, and carbon steel. Typically, ferrous metals are less expensive than non-ferrous metals as they are often used in a variety of applications including aerospace components.

Corrosion Resistance Common for Non-Ferrous Metals

For non-ferrous metals, the absence of iron makes many of the metals in this group less prone to possible corrosion and rust. These metals are very malleable, light weight and have a low tensile strength. They may also be magnetic or non-magnetic, providing additional options based on the applications.

A main advantage to non-ferrous metals involves their thermal and electrical conductivity. When a metal has these types of characteristics, it means that both electricity and heat can pass through the metal easily with little resistance. In the case of casting parts used in electrical or electronic systems, metals with electrical conductivity allows for the current to pass through while the generated heat from the electrical current can be drawn away and dissipated. This feature prevents the overheating of systems that could lead to degradation and failure.

Non-ferrous metals are often found for pipes, electrical components, and aircraft. Copper, aluminum, zinc, nickel, brass, and lead are some non-ferrous metals.

Selecting Between Ferrous and Non-Ferrous Metals

To decide which metals to use for investment castings, think about the application and what will be the function of the metal. Does the application require a metal strong enough to stand up to harsh environments, allow for the passage of electrical currents, or need to be lightweight for portable devices?

You should also focus on what other materials will interact with the metal during the application’s operation. Will there be a material that will cause excessive wear and tear to the metal part? If so, a sturdier and stronger metal may work out for the best.

Lastly, keep in mind the price. You may require a metal to have magnetic qualities. While you can obtain this from non-ferrous metals, you may have a lower budget where a ferrous metal would also work for the casting while saving on costs.

For more information about investment castings and the types of metals to use for your project, contact Impro.