What is Investment Casting?

Part 1 –
What is Investment Casting?

When you search the web for investment casting what do you find? Many educational sources of information on investment casting tend to simply miss the mark; many of these articles focus more on craft/jewelry investment casting or simply lack the knowledge of industrial investment casting to truly be a useful source. Many articles from casting suppliers are very brief and serve more as an advertisement opportunity than an educational source. We have realized these gaps here at Texmo and want to help fill the void. Whether you are a potential investment casting buyer, a student researching this type of manufacturing for the first time, or just curious about the process we hope the information below is a helping factor in whatever action you next take.

So what is investment casting? In the simplest terms, investment casting is a manufacturing process in which a wax pattern is used to shape a disposable ceramic mold – which then, in turn has molten metal cast into it.  You may also hear this process referred to as “precision casting” or “lost wax casting” but all describe the same process.  Investment casting has been around for roughly the last 5,000 years. Its origins involve sculpting beeswax patterns, using clay as the ceramic mold, and casting low melt point ores that could be melted over a fire. Today’s industrial processes follow roughly the same sequence of operations but allow for higher precision, faster processing times, and scaling to handle higher volumes of parts. A modern-industrial investment casting foundry will include high levels of automation, advanced engineered waxes and ceramics, premium alloys, and advanced data collection via IoT.

The video below provides a brief overview of the process.

Why Investment Casting?

So what purpose does the investment casting process serve? The investment casting process can provide net shape, or near-net shape castings, which can save customers by reducing cost in material, labour, and machining. Many different types of metals can be cast with the investment casting process with most industrial foundries focusing on carbon steels, low alloy steels, high alloy steels, tool steels, cobalt alloys, cobalt-chrome alloys, nickel alloys, and nickel-copper alloys. Due to the benefits of investment casting and a wide range of potential geometries and materials, the process is well suited for a wide range of applications including gas turbine components (both IGT and aerospace), medical devices and equipment, sensors, valves, compression systems, automotive components, industrial equipment components, hardware, sports equipment, gears, and golf club heads.

Due to its complexity, investment casting can be a relatively expensive process but its benefits far outweigh the costs. Investment castings in most industrial foundries can range from a few grams to 25 kilograms. The investment casting process can produce high complexity components without the need for additional machining due to its excellent surface finish and no need for draft angles. It is the most accurate casting process and while it cannot produce parts with as high of precision as machining it can perform to a very high degree of precision. Tolerance capability is dependent on the linear size of the dimension and the geometry of the part but investment casting can hold tolerances as low as 0.003” (76 microns) without the need for additional processes. There is an initial tooling cost that will usually range from four to five figures (USD) but for high volume orders, this initial cost is quickly offset by the time, labour, and machining costs that are saved. For regular runs as low as 25 parts, this tooling cost can quickly be returned to the customer in savings.

Please be sure to check back for updates to this series where we will cover the process in more detail. Upcoming posts for the “What is Investment Casting?” series will include Wax Processes, Shell Processes, and Cast/Post-Cast Process. Part 2 will be released next which will give more detailed insight into the wax processes involved in investment casting.