Home 9 Die Casting 9 What is Investment Casting? Process and Materials

What is Investment Casting? Process and Materials

Author: YiNuo Zhang
Published on: 2024-02-11
Categories: Die Casting

“The significance of investment casting lies in its ability to produce complex shapes and detailed parts with a finish. It minimizes the need for machining, bridging the gap between design complexity and manufacturing capability.”

Among the different casting methods, investment casting stands out for its ability to produce parts with exceptional precision. But, what is investment casting? It is a manufacturing process that involves creating a wax model of the desired part and coating it with a refractory material to form a mold. Then, melt out the wax to pour molten metal into the cavity. Following that, solidification and breaking of refractory gives the final part. 

In this article, we will discuss investment casting in detail. It will cover the working process, suitable metals, pros & cons, applications, etc. 

 

What is Investment Casting? Definition

Investment or lost-wax casting is a manufacturing process that produces parts with exceptional precision and detail. The process begins with creating a wax model of the desired part. Meanwhile, the wax model is which is encased in a ceramic shell. Once the shell hardens, the wax melting leaves a cavity to pour the molten metal. After the metal solidifies, the breaking of the ceramic mold reveals the final cast part. 

Investment casting 

The investment casting can work with different metals, including steel, aluminum, and titanium. It makes casting suitable for industries such as aerospace, automotive, and medical devices. Furthermore, investment casting is known for its ability to create parts that require minimal machining and finishing, saving both time and resources.

Moreover, it is the method of choice for small to medium-sized components for applications where the material’s properties, such as strength and corrosion resistance, are critical.

Related: What is Die Casting? Die Casting Process and Overview 

 

How does Investment Casting work?

Investment casting creates detailed and complex metal components. The process begins with creating a wax model, a replica of the desired part. This model is attached to a wax sprue, forming a tree-like assembly. Then, the assembly is dipped into a ceramic slurry, coated with fine sand, and left to harden. The multiple repetitions of this step build a thick ceramic shell around the wax models.

Investment casting process 

Once the ceramic shell has dried and hardened, it is heated to melt and burn out the wax, leaving behind a hollow cavity in the shape of the parts. This stage is crucial as it prepares the mold for the molten metal. The high temperature also strengthens the ceramic mold, ensuring it can withstand the stress of the casting process. 

After the wax removal, molten metal is poured into the cavity of the ceramic shell. The metal then cools and solidifies, taking on the exact shape of the original wax model. Next, the ceramic shell is broken away to reveal the metal parts. These parts are then cut from the sprue, and any necessary finishing processes are applied.

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What are the Investment Casting Materials?

Investment casting stands out for its versatility in working with many materials. It can handle metals with high melting temperatures and those that are difficult to machine, providing flexibility in material choice to meet specific property requirements. 

Here are the common investment casting metals;

1. Stainless Steel

Steel Investment Casting is a choice for excellent corrosion resistance, durability, and strength. It is ideal for parts that require long-term reliability in harsh environments. Furthermore, stainless steel’s aesthetic appeal makes it suitable for consumer goods. This material adapts well to the investment casting process, allowing for parts with complex shapes without sacrificing mechanical properties.

2. Aluminum Alloys

Aluminum alloys are favored for investment casting when weight reduction is crucial without compromising strength. They offer excellent machinability, good thermal and electrical conductivity, and corrosion resistance. These properties make aluminum alloys suitable for the automotive, aerospace, and electronics industries. Investment casting with aluminum alloys facilitates the production of lightweight, durable parts with intricate designs.

3. Titanium

Titanium is renowned for its strength-to-weight ratio, corrosion resistance, and ability to withstand extreme temperatures. These characteristics make it an ideal material for aerospace, medical, and military applications. Next, manufacturers can produce titanium parts with precise dimensions and complex geometries. 

Titanium investment casting part

4. Cobalt Alloys

These materials are known for their wear resistance, high-temperature stability, and corrosion resistance. Therefore, they are suitable for investment casting parts used in harsh environments. Meanwhile, these alloys are common in the medical & surgical instruments, aerospace, and automotive industries.

5. Nickel Alloys

They are chosen for their high-temperature resistance and excellent mechanical strength. They are useful in harsh environments where oxidation and corrosion resistance are required. For example, chemical processing and energy sectors. Investment casting of nickel alloys enables the creation of parts with complex shapes and detailed features, meeting the stringent requirements of industrial applications.

6. Copper Alloys

Mainly bronze and brass are selected for investment casting because of their excellent electrical conductivity, thermal conductivity, and corrosion resistance. These materials are ideal for creating decorative items, electrical components, and marine hardware. 

7. Precious Metals

Precious metals like gold, silver, and platinum are also compatible with investment casting for jewelry, art, and dental applications. Investment casting allows for the detailed and intricate designs characteristic of these fields.

 

Pros of Investment Casting

  • High-Dimensional Accuracy and Surface Finish: Investment casting produces parts with excellent dimensional accuracy and smooth surface finishes, reducing the need for secondary machining.
  • Complex Geometries: It allows for components with intricate shapes and details that would be difficult or impossible to achieve with other methods like machining. 
  • Versatile Material Options: Versatility in metal choices brings flexibility in material selection to meet specific application requirements.
  • Reduced Waste: The precision of the process results in minimal material waste. So, it is more efficient and cost-effective for detailed parts.
  • Tooling Longevity: The ceramic molds used in investment casting can produce many parts before requiring replacement. 

 

Cons of Investment Casting

  • Higher Cost for Low Volume Production: Initial setup and tooling costs can be high. Therefore, it is less cost-effective for very small production runs.
  • Longer Production Time: The multi-step process of creating wax patterns, ceramic molds, and casting can lead to longer lead times than other methods like high-pressure die casting. 
  • Size Limitations: While investment casting is excellent for small to medium-sized parts, it may not be suitable for very-large components.

 

Rapid Prototype Investment Casting

This investment casting approach allows engineers and designers to create prototypes within days. So, it significantly accelerates the development cycle of parts or products.

Investment casting prototypes

In Rapid investment casting, 3D-printed wax or resin patterns replace the need for tooling, facilitating quick iterations and modifications based on testing feedback. As a result, this adaptability makes it an ideal choice for industries aiming to innovate rapidly and reduce the time to market for new products.

Rapid Prototyping Services

  • Digital to Physical Transition: 3D printing converts a CAD into a physical pattern, eliminating traditional mold-making steps.
  • Complex Designs Made Possible: You can experiment with intricate details and complex geometries. So, it makes you free from conventional tooling limitations.
  • Streamlines Prototyping: Rapid prototype investment casting accelerates rapid prototyping.
  • Cost Reduction: Significantly lowers development costs by reducing waste and eliminating the need for expensive tooling.

 

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Gravity Die Casting: Overview, Process, and ApplicationsWhat are the Investment Casting Applications?

This process shines where intricate designs and material integrity are paramount. From aerospace to medical devices, investment casting enables the creation of parts that might otherwise be impossible or prohibitively expensive with traditional manufacturing methods.

Aerospace Parts

Investment casting aerospace parts 

In aerospace, investment casting produces parts with high strength-to-weight ratios and durability. Some investment casting aerospace applications are turbine blades, engine components, and airframe structural parts. Subsequently, these casting components can withstand extreme temperatures and stresses.

Medical Devices and Instruments

Next, the medical industry benefits from investment casting to manufacture surgical instruments, implants, and device components. It allows for parts with complex shapes and smooth surfaces required in medical applications. Meanwhile, you can choose materials like titanium and stainless steel due to their biocompatibility and strength.

Automotive Components

Investment cast automotive part

Investment casting finds extensive application in the automotive sector. It is popular in high-performance and luxury vehicles. This method can cast engine parts, transmission components, and structural elements. Meanwhile, precision engineering for automotive casting ensures optimal performance and reliability. Overall, investment casting enables the production of lightweight designs that contribute to improved fuel efficiency and vehicle dynamics. 

Jewelry

The jewelry industry relies on investment casting to reproduce intricate designs with exceptional detail and surface finish. Precious metals like gold, silver, and platinum are cast into exquisite pieces that highlight the craftsmanship and artistry of designers. Moreover, investment casting accommodates the delicate features and complex patterns in jewelry.

Energy Sector

Investment casting for the oil & gas industry

For the energy sector, investment casting produces components for power generation equipment, including turbines and generators. These parts must endure harsh conditions and high stress, necessitating the use of materials that can withstand such environments. The process’s precision and ability to work with high-performance alloys make it a go-to choice for creating durable, efficient components for renewable and non-renewable energy sources.

Defense and Military Applications

The defense industry employs investment casting to fabricate parts for firearms, vehicular components, and aerospace defense systems. It addresses the need for parts that can perform reliably under extreme conditions. Meanwhile, investment casting enables the production of components with the strength, precision, and durability required for military applications.

 

What is Large Investment Castings?

This investment casting variation is for large and complex components. It accommodates sizable parts for industries like aerospace, where large structural components and engine parts. Here, the ability to produce large, intricate shapes with high dimensional accuracy of investment casting ensures that even the most challenging designs are feasible, merging strength with complexity.

Large investment casting 

The process for large investment castings involves specialized equipment and techniques to manage the increased scale and weight of the molds and the molten material. 

  • Careful attention to detail is essential in preparing the wax models
  • Coat wax models with refractory materials
  • Control the metal pouring process to avoid defects.
  • The scale of these operations necessitates rigorous quality control. 

Furthermore, energy, marine, and heavy machinery industries benefit significantly from large investment castings. These sectors often require components that combine durability with detailed features. Here, the adaptability of investment casting to various alloys means custom parts that meet specific environmental and mechanical demands. 

Read more: Gravity Die Casting: Overview, Process, and Applications

 

Cast Your Metal Parts at Prolean: Precision at Low Cost

At Prolean, we specialize in transforming your concepts into high-quality metal parts through our advanced casting services. Our expertise spans various casting methods, including investment casting, die casting, vacuum casting, and sand casting, to cater to diverse industry needs.

Die casting service

Our casting engineers leverage advanced technologies and manufacturing facilities to ensure that each part we produce meets stringent quality standards. Meanwhile, we have a separate team to work closely with clients. As a result, we can understand your specific requirements and cast the part accordingly. 

We handle projects of any scale, from small, intricate components to large, complex assemblies. Next, our rigorous quality control process ensures that every part that leaves our facility has been thoroughly inspected and meets all specifications. Choosing Prolean for your metal casting needs means partnering with a team committed to excellence and innovation.

 

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Summing Up 

Overall, investment casting is a wise manufacturing option for producing high-precision, detailed parts across several industries. It allows components with complex geometries that other methods cannot achieve, making it ideal for customized or intricate designs. However, some considerations are essential to achieve quality investment casting parts. A well-designed plan can only accommodate the process’s unique requirements, including allowances for shrinkage and the creation of molds.

Finally, understanding what is investment casting is the first step toward leveraging its full potential in manufacturing. It involves a detailed process, from creating a wax model to casting metal in the created mold, requiring specialized knowledge and equipment.

 

FAQs

What do you mean by investment casting?

Investment casting, also known as lost-wax casting, is a precision casting process for creating intricate and detailed metal parts by using a wax model, coating it in a ceramic slurry, melting out the wax, and pouring metal into the cavity.

Are investment casting parts durable?

Yes, investment casting parts are durable. The process allows for the use of high-strength alloys, ensuring the produced components possess excellent mechanical properties and longevity, suitable for demanding applications.

Which materials are suitable for investment casting?

Several materials are compatible with investment casting, including stainless steel, aluminum, titanium, and various alloys.

Is investment casting expensive?

Investment casting can be more expensive than other casting methods due to its intricate process and the materials used. However, its ability to produce complex shapes with minimal machining often results in overall cost savings for detailed parts.

What is the difference between die casting and investment casting?

Die casting involves forcing molten metal into molds under high pressure and is suitable for the high-volume production of parts with thinner walls and less complexity. Investment casting is better for creating intricate, detailed parts with superior surface finishes and allows for a broader selection of materials.

 

Resources

  1. Poli, C. (2001). Metal Casting Processes. In Design for Manufacturing: A Structured Approach (pp. 115-126). https://doi.org/10.1016/B978-075067341-9.50010-0
  2. Bralla, J. G. (1999). Design for Manufacturability Handbook (2nd ed.). The McGraw-Hill Companies, Inc. ISBN: 9780070071391. https://www.accessengineeringlibrary.com/content/book/9780070071391/chapter/chapter53 

2 Comments

  1. exhibition catalogues

    DO you assists in importing investment casting equipments?

    Reply
    • Dikendra Acharya

      No! We only provide Investment casting molds, molded parts, and related consultations.

      Reply

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