Investment Casting Process

The Magic of Investment Casting

Investment casting is a centuries-old technique, offering the ability to create high-precision parts with minimal surface imperfections. The process involves creating a wax pattern, encasing it in a ceramic shell, melting out the wax to create a cavity, and finally pouring molten metal into the cavity. Once the metal solidifies, the ceramic shell is broken away, revealing a finished component that requires minimal post-processing.

Investment Casting Process at CFS Foundry: A Step-by-Step Guide

Investment casting process in CFS foundry is operated with the most advanced technology in China. We can produce top level investment castings in a variety of dimensions and shapes. In this process, all metal alloys are available, we can customize investment castings according to your material specifications,and even material compositions is feasible for production. To ensure the best quality, we will do quality control in each investment casting process. Below is the steps of a whole investment casting process in our foundry:

Step 1. Tooling Making

To achieve precision products, making tooling is the first step to start investment castings. Such tooling or pattern will be precision machined by CNC center. So tooling cost will be charged from our customers when sample order of a new product is placed. But it is just one-off paid, and we will not ask for this fee for further orders.



Step 2. Wax Injection and Pattern Assembly

After a pair of casting patterns is completed, we will first make wax pattern, such wax pattern is obtained by injecting wax into the pattern. And you will see a model with the same dimensions of desired products. Again, we will repeat the injection job for more wax patterns. Then assemble these wax patterns onto the sprue. Finally hang these pattern assemblies in the room temperature for drying.



Step 3. Shell Building

In this step, the pattern assembly will be dipped into a ceramic slurry, and coated with a refractory material. This process needs to be repeated several times until reaching a certain thickness and strength. Thus, the cetamic shell is built and then dried in an atmospherically-controlled environment.



Step 4. Dewaxing

Placing the shell in a steam autocalve and rapidly heated, so that the wax will be melt and run out through the gate and pouring up under high temperature.The ceramic shell molds must be fired to burn out the last traces of pattern material and to preheat the mold in preparation for casting, usually in the range of 1,600-2,000 degrees Fahrenheit. So investment casting also named as “lost wax casting”.


Step 5. Casting

Casting is the key step in the whole investment casting process. After dewax, we will first melt the steel ingots into liquid status, and pour the liquid metal into the sprue, then cool it under room temperature for a while.





Step 6. Knock out

Break the ceramic shell, and cut the individual investment castings from the sprue. Finally remove the excess metal from casting body by grinding.




Step 7. Heat Treatment

To improve the mechanical properties of casting blanks, heat treatment is usually done after finishing castings. Main heat treatment processes are: Normalizing, tempering, annealing, hardening and tempering, carburizing, ect. Pls note, heat treatment is operated only when customers have such requirements, and extra cost will be counted.


Step 8. Shot Blasting/Sand Blasting

To remove scales and achieve better surface finish, investment castings will be shot blasted or sand blasted by small steel balls.So all the foundries must be equipped with shot blasting machines.




Step 9. Surface Treatments

To protect products from rusting, castings will be dipped into anti-rust water or oil. Of course, other surface treatments can also be performed in this step like paint spraying, galvanizing, etc.




Step 10. Inspection

Inspection is also a necessary step for quality investment castings. Our engineer will do dimensional inspection, 100% surface inspection, inner defects inspection and other inspection jobs according to requirements of products. Only ensure all the products are qualified, can we arrange delivery to our customers.



Step 11. Package

As all the products are exported to overseas market, so, normally we will pack investment castings with ploybags, and then put them into standard wooden cases. Of course, all the package must be carried out on the basis of free from damage. We can also supply custom package service according to customers’ special requirements.



Advantages of Investment Casting Process

1. Excellent Detail and Accuracy:

Investment casting can produce parts with exceptionally high detail and accuracy. The process allows for intricate geometries, undercuts, and complex forms that are not possible with other casting methods. Additionally, it can deliver parts with excellent dimensional accuracy, minimizing the need for secondary machining.

2. Superior Surface Finish:

Parts produced by investment casting have a smooth surface finish, often better than other casting methods. The superior surface finish reduces the need for additional surface treatment or finishing processes, leading to cost savings and quicker production times.

3. Material Versatility:

Investment casting is compatible with a wide range of metals and alloys, including steel, stainless steel, aluminum alloys, bronze, and much more. This versatility ensures that you can select the most suitable material for the specific properties required in your final part, such as heat resistance, strength, or corrosion resistance.

4. Suitable for Complex and Intricate Designs:

Investment casting is an excellent choice for producing complex and intricate parts that would be challenging or impossible with other manufacturing methods. This is possible because the process uses a wax pattern and ceramic mold, which can accommodate a high level of detail and complexity.

5. Cost-Effective for Small to Medium Production Runs:

Investment casting is particularly cost-effective for small to medium-sized production runs. The process involves fewer steps and less waste compared to other methods. While the initial tooling cost can be high, it is often offset by the lower per-piece cost for the production run.

6. Produces Near-Net-Shape Parts:

Investment casting is known for producing near-net-shape parts. This means that parts require little to no additional machining or finishing after casting, saving time and reducing costs. It is particularly beneficial for parts with complex geometries or parts made from hard materials that are difficult to machine.

In summary, the investment casting process offers numerous advantages that make it a viable choice for many manufacturing scenarios. From delivering highly detailed, accurate parts to offering a wide range of material choices, investment casting stands out as a versatile and effective manufacturing process.

Tips on Selecting Investment Casting Process

Investment casting is a valuable manufacturing process that can deliver exceptional results. However, it’s essential to approach the process thoughtfully to ensure it aligns with your project’s needs. Here are some tips on selecting the investment casting process, specifically considering CFS Foundry as your manufacturing partner:

1. Evaluate Your Design Needs:

The first step is to evaluate your part’s design. Investment casting is particularly suitable for complex and intricate designs that other methods struggle with. Look at the complexity, details, and features of your design to determine if investment casting is the best choice.

2. Consider the Material:

CFS Foundry can work with a wide range of metals and alloys, allowing you to choose the material that best fits your requirements. Consider factors such as strength, heat resistance, and corrosion resistance when selecting the material.

3. Assess Production Volume:

Investment casting can be economical for both small and large production runs. However, the initial costs for creating the wax patterns and ceramic molds can be high, making it more cost-effective for larger runs. Assess your production volume and discuss it with the team at CFS Foundry to ensure the process aligns with your budget.

4. Consider Lead Time:

While CFS Foundry is known for its efficiency, the investment casting process involves several stages that require time for completion. Be sure to discuss your project timeline with the foundry to ensure they can meet your deadline.

5. Review Post-Processing Needs:

Although investment casting typically produces parts with excellent surface finish and dimensional accuracy, some projects may require additional post-processing, such as machining, heat treatment, or specific surface finishes. CFS Foundry offers these services, so discuss your post-processing needs with them to ensure they can meet your specifications.

6. Partner with an Experienced Foundry:

CFS Foundry has extensive experience and a proven track record in investment casting. They have the knowledge and expertise to guide you through the process, offering advice on design optimization, material selection, and more. Working with an experienced foundry like CFS will not only ensure high-quality results but also smooth the overall project management process.

By taking these considerations into account, you can make an informed decision about using the investment casting process and partnering with CFS Foundry. Our dedication to quality, customer service, and technical expertise makes us an excellent choice for your investment casting needs.