is one of the oldest manufacturing processes that is still in use today––in fact, investment casting has been widely used to form metal parts for thousands of years. This versatile metalworking method allows manufacturers to create complex components of any size with great accuracy, intricacy, and consistency.
Investment casting is known for the variety of materials that it can accommodate, including a wide range of metals and high-performance alloys. Some of the most commonly used metals and alloys in investment casting include:
Because of its versatility, investment casting is used in a number of industries. It is particularly well-suited to high-temperature applications in the aerospace and automotive.
Investment casting involves the use of a wax pattern coated with a robust ceramic material. After allowing the ceramic material to harden around the wax pattern, the user heats the covered wax pattern until the wax melts. After draining the wax, the hardened ceramic can be used as a cast into which molten metal can be poured. Below, we dive more closely into the step-by-step process of investment casting.
Investment casting remains in widespread use after thousands of years because of the numerous advantages that it offers over alternative metalworking techniques. Compatible with nearly every metal and alloy used in heavy industry today, it enables users to cast strong but thin-walled and lightweight components of great detail and complexity regardless of the material used.
Because of its high accuracy and the superior surface finishes that it yields, investment casting largely eliminates the need for secondary machining, helping customers save costs and shorten production timelines.
Since 1998, Impro has provided high-precision, high-quality casted metal components for customers across industries. Our talented team of experts has extensive experience with a variety of casting processes––including investment casting––ensuring that we can provide any client with accurate, reliable, and consistent casted parts for use in a wide range of applications. Regardless of your needs, we’re here to supply you with a durable and efficient solution to your operational challenges.
Investment Casting can yield any required shape using almost any metal alloy; design functionality can be maximized due to the amount of materials to choose from. Various features can also be incorporated with the right mold. The most popular materials that are suitable for Investment Casting are stainless steel, carbon steel, copper, aluminum, and superalloys.
Investment Casting is the preferred process for creating complex castings as it allows for complex parts and components to be cast. Sections with thin walls and features, such as undercuts, can be cast with ease. Investment Casting can also produce a superior surface finish up to Ra 3.2 and achieve dimensional and geometrical accuracy to meet special requirements such as weight.
With Investment Casting, designs do not have to be altered to add different angles or taper. In addition to providing design flexibility for manufacturing complex, one-piece structures, this is an added advantage as it reduces secondary machining time and also drastically reduces material and processing cost.
Investment Casting is a superior process that offers substantial cost reduction in supply chain management, such as sourcing management, transportation, logistics, welding/assembly process cost, match/fitup issues, scraps and more. It can also reduce labor time, as well as significantly reducing wall thickness while generating parts that are consistent and smooth. The drastic drop in labor time reduces lead time and also cost of castable applications. This makes it a cost-effective alternative to multiple-piece weldment or assembly operation. A consistent casting process can also lead to a more efficient shipping frequency, in addition to, lowering costs even further through better function and lower scrap
Cost-Savings At-A-Glance:
As we discussed in Part 1 of our series, the freedom of design that comes with Investment Casting reduces secondary machining time and also drastically reduces material and processing cost. Investment Casting also allows for the finest details to be cast while saving on materials and energy during the course of production, and it can open doors to great cost reduction in manufacturing such as in reducing the number of stages in a project. During the production of highly complex, intricate parts or assemblies, no other fabrication technique can equal the cost-efficiency of investment casting.
Other processes can have a significantly higher cost of materials used for required tooling and fixtures. Investment Casting provides alternatives for tooling materials, such as Aluminum which are less expensive and are easier to cut and maintain. This causes a reduction in start-up costs, which in turn reduces the cost of the process as a whole. Investment Casting also uses wax, which goes easy on tooling, allowing it to maintain consistent parts for subsequent uses. In addition, tooling for Investment Casting has a long-life span, usually lasting for tens thousands of parts or more before a replacement tooling is required.
Investment casting can produce a wide variety of products and prototypes, but it is important to choose the correct investment casting material for your application. The right material helps you get the desired functionality, save on the cost of materials, eliminate unwanted casting defects, and limit the need for secondary processes after the casting is complete.
Final parts can display smooth surfaces and dimensional precision while allowing for lower weight, thin walls, or other beneficial properties. Determining which properties can be successfully incorporated into your part largely depends on material choice.
There is a large selection of alloys to choose from during the material selection process for These include:
Stainless steels feature superior durability in comparison with many other materials. The potential of the material has led to increased use in investment casting by designers and engineers. Applications for stainless steel include gearbox parts in automotive applications, various gears, camp components, and golf club heads.
Low alloy steels are among the most frequently used steels in the mechanical world due to their affordability and beneficial mechanical properties. Specialized heat-treating processes make it possible to engineer parts that have differing properties in different areas of the same workpiece. For example, varying heat treatments can be used to make one surface tough and impact-resistant, while another surface becomes wear-resistant.
Aluminum alloy is the most used material in investment casting. Industries that use it most frequently include aerospace, avionics, electronics, and military.
Castings are now offered for demanding applications like airframe components thanks to the material’s improved strength and the availability of quality castings made from aluminum-silicon-magnesium alloy.
Carbon steel is a common low-cost material that comes in a variety of grades, with the classifications varying based on the amount of carbon content. The strength, ductility, and performance of carbon steel can be improved in industrial applications through heat treatment. Its ferromagnetic properties make carbon steel useful in motors and electrical appliances. It is safe, durable, and has a high structural integrity, making it one of world’s most frequently used alloys.
Investment casting enables manufacturers to produce precision-engineered parts while minimizing material and energy waste. The word “investment
Titanium is a metal valued for its high strength-to-density ratio, corrosion resistance, and temperature resistance. Despite the fact that titanium is one of the most common naturally occurring elements on the planet, it’s expensive to separate from other elements into its fundamental metallic form. Titanium bonds easily with oxygen, which creates an oxidized layer for enhanced corrosion protection in finished products; however, this same characteristic makes it difficult to manufacture into metal products. In fact, particular processes must be used to prevent it from being exposed to and bonding with other elements.
Due to its unique properties, titanium is often used to create aerospace, medical, and industrial parts, as well as consumer products and sporting goods. One of the most common methods for creating titanium products is investment casting. Titanium investment casting can produce highly detailed and complex parts with a smooth surface and minimal need for finishing work. This blog examines the titanium investment casting process, properties of titanium castings, and their wide range of uses.
Investment casting is a versatile process used with a variety of materials to create intricate components with a smooth surface finish. Due to the highly reactive nature of titanium, investment casting with this metal requires modifications to the overall process. Titanium investment casting follows these basic steps:
Titanium offers numerous distinct advantages over other metals, including:
The unique properties of investment cast titanium parts make them particularly useful in a wide range of industries and applications. The most common include:
Other industries and applications where titanium casting is found include pharmaceutical and chemical production, oil and gas, marine, automotive, transportation, construction, and consumer products and sporting goods.
Although titanium is versatile, the purification and production processes make it more expensive to manufacture than some other metals, like aluminum and steel.
At Impro, we are a premier manufacturer of high-quality engineered metal parts and components suitable for use in critical and demanding applications, such as those found in the aerospace, automotive, and construction industries. One of our core services offered is Over the years, we have received various questions and encountered numerous misconceptions about the process. The following points aim to answer and address some of the most common ones.
False. Investment casting is suitable for both large and small parts. Some of the greatest advantages of the investment casting process are reflected in the manufacture of large castings.
False. At Impro, we use silica sol as our investment casting shell material to achieve a tighter tolerance range—CT4-CT6. However, depending on the part design and the process technology, the tolerance in the finished piece may not be as tight.
False. Investment casting accommodates a wide range of metals. In particular, aluminum, titanium, and steel alloys are well-suited for use in such process.
False. The wax patterns and ceramic molds used for investment casting are destroyed when the castings are produced and removed, respectively. As a result, new wax patterns and new ceramic molds must be created for each production run of an investment cast part. In contrast, the molds used in permanent molding casting operations are reusable, allowing industry professionals to use them for many production runs.
False. In an investment cast part design, it is not necessary to include a pattern taper. Since the process uses liquid slurry to create the part mold, the part design can feature almost any shape with a high degree of freedom regarding complex and intricate elements.
False. Both the and investment casting processes have a parting stage. In sand casting, the stage refers to the process of splitting the mold to release the finished piece and, in investment casting, it refers to the process of melting the wax to create the ceramic mold for part production. While these processes occur at different stages during their respective casting operation, the key distinction lies in the surface finish achieved.
False. When used alongside machining processes, investment casting can lower production costs. For example, an investment cast part can be produced to reasonable part tolerances and/or combine individual assembly components into a single unit. Once cast, the part can then undergo machining for only the critical areas. Through this combined production process, industry professionals can reduce the overall time and labor required to produce the part.
Casting is one of the oldest manufacturing methods, with early processes dating back thousands of years and updated methods going back to about 1893. While casting techniques and technologies have vastly improved since then, the basic principles remain the same. In essence, melted material is poured into a pre-shaped cavity or mold, where it cools and solidifies into the desired shape.
Manufacturers employ different casting techniques depending on the part and production specifications. Two of the most common casting processes in modern operations are investment casting and die casting. The following blog aims to provide an overview of each process—including what each is, how they work, and their key advantages, disadvantages, and differences.
Involves the creation of a wax pattern in the shape of the desired part. The pattern is coated with ceramic or another heat-resistant material to create a disposable cast. Once the outer material has hardened, heat is applied to melt the wax pattern, leaving a cavity in the shape of the component. Molten metal is poured into the mold and allowed to cool. The outer shell is then broken to reveal the cast part.
Investment cast components are highly detailed, precise, and accurate. Once freed from the ceramic mold, they exhibit smooth finishes that generally require little to no finishing. Although a new wax pattern and ceramic mold must be created for each component, production costs for investment casting operations can be equal or less than those of other casting operations since minimal additional work is required beyond the casting process. Automating operations further reduces labor costs.
Investment casting is highly versatile, accommodating a wide range of ferrous and non-ferrous metals. As such, it is used to manufacture numerous high-precision, high-accuracy components, such as those for aircraft systems, automobile engines and brake systems, industrial assemblies, and dental and medical devices.
Die casting uses pre-made tool steel dies in the shape of the desired components. Molten material is forced into a die at high pressures and left to cool. Once solidified, the cast piece is ejected from the die using ejector pins.
Die casting presents several advantages over other manufacturing methods. For example, it accommodates a broader range of materials, allows for thinner part walls, achieves tighter dimensional tolerances, and produces finer surface finishes. Additionally, while its higher production costs are somewhat prohibitive for low-volume runs, it is a cost-effective option for high-volume runs.
Die casting is often used for the production of small and thin metal components. These parts find application in many industrial and commercial products, such as automobiles and consumer electronics.
Aerospace and aviation companies face unique challenges for their equipment and components. First, they require highly complex and precise parts that perform their functions reliably and efficiently. In addition, these components may experience extreme environmental stresses that can impact their performance. From extreme temperature differences to corrosive elements, the components must be designed to withstand these stresses and resist corrosion and wear that could cause parts to fail when performing critical functions.
Investment casting and surface treatment solutions play critical roles in aerospace casting. These techniques ensure that repeatable products of high quality are created on time and at the necessary demand levels. Learn more about how investment casting and surface treatments create these required components.
Investment casting has been used for more than 5,000 years to create a range of products for diverse applications. Today, it is widely used and reliable casting method for aerospace components.
Investment casting involves creating a pattern out of wax for the part or component that will be created. Then the wax pattern is placed on a gate and runner metal delivery system. A ceramic slurry is created as the wax pattern is dipped into this slurry and allowed to dry. The wax is later removed as the ceramic shell becomes the mold that will be filled with the molten metal to create the component.
There are enormous benefits to using investment casting. This method creates complex geometries and intricate designs that are required for components in the aerospace industry. In addition, the components come out with a very smooth finish that has fewer blemishes and requires less polishing and processing to be done. A range of different metals can also be used in investment casting, such as aluminum, stainless steel, low alloy steel, titanium alloys and super alloys. The cast metal components can come in a range of sizes from a few ounces to hundreds of pounds.
Treating the surface of metal components not only improves its aesthetic appearance, it also provides additional benefits. Applying a coating on top can also protect the component from corrosion caused by environmental conditions or chemicals that may be introduced in the working environment. The treatments can also slow down wear and tear to components so that the parts last longer. There are numerous surface treatments that may be used during the aerospace casting process.
Anodize treatment: The anodize treatment creates an extra protective natural oxide layer on the surface that is created by the component’s own metal materials
Chemical conversion coating: This process uses an electro-chemical or chemical process to adhere the metal coating to the surface.
Passivation: This treatment helps to remove the iron from the surface of the metal that can cause corrosion.
Plating: Plating involves placing a layer of metal onto the component’s surface. There are numerous plating techniques that may be used, including electroplating that uses an electric current and chemical plating.
Etching: Etching treatment removes a very thin layer of the component’s surface.
Manufacturers use a range of techniques to create complex parts and components. One of the oldest methods that is still used today is investment casting. This process involves creating the item out of wax and then building a ceramic shell around it. Once the shell is complete, the wax is melted out (called dewaxing) before the molten metal is poured into the ceramic shell. Once the metal solidifies, the ceramic shell is removed as the part is now created.
There are numerous waxes that can be selected. The type of wax used will be based on several factors including flow properties, whether the wax will be reclaimed and recycled, dimensional consistency, surface finish and the requirements of the application. Several waxes that you will often hear about are filled pattern wax, non-filled pattern wax, runner wax, water-soluble wax and sticky wax.
Filled pattern waxes are a type of investment casting wax that has fillers added. These fillers can provide certain properties to the casting to ensure strength, dimensional stability, lower thermal expansion and minimal shrinkage. The types of fillers that are found in filled pattern waxes will vary based on the supplier, yet some common fillers may include bisphenol-A (BPA), organic fillers, terephthalic acid, and cross-linked polystyrene.
Both small and large wax pattern productions can use filled pattern waxes. Two major advantages to these waxes are that they have low thermal expansion and minimal shrinkage. They don’t require wax chills to be placed into the cavity of the patterns to prevent shrinkage as the wax solidifies.
This wax is often used when you are looking for more dimensional control of the created part or component and when using a wide range of injection temperatures. Due to the filler added, some wax may remain in the ceramic shell after the dewaxing process as it takes longer for the wax to be burnt out. Filler pattern waxes can be difficult to reclaim and recycle depending on the density of the filler material.
Non-filled, or unfilled, pattern wax blends contain less filler materials. This type of wax offers consistent mechanical performance and thermal performance. They are typically used for small and medium wax patterns when there are complex geometries and very defined patterns. Non-filled waxes have exceptional flow properties.
A main advantage to non-filled waxes is that they provide a high surface quality. So the ceramic mold will have fewer cracks and defects. It also completely dewaxes from the ceramic shell as it can be reclaimed and recycled.
Care must be taken when using non-filled waxes in investment casting processes. Due to a slower solidification, the surface of the pattern can sink. There may also be unwanted shrinkage along cross sections of the pattern depending on the wax temperature. Depending on the part configuration, the use of wax chills may be necessary with non-filled pattern waxes to avoid material shrinkage.
Runner wax blends are used by investment casting companies when desiring exceptional mechanical strength and lower viscosity. This type of wax has a lower melting point than pattern waxes. So it will drain completely out of the ceramic mold during the dewaxing process without the need to use higher temperatures.
Advantages to runner wax is that it has good soldering strength and minimum thermal expansion. The workers can handle the wax without worrying about the part breaking in the ceramic mold. The wax pattern will need to be immersed in water and stored there until it completely solidifies.