Stainless steel is a highly sought-after material in various industries due to its excellent mechanical and chemical properties. It is durable, resistant to corrosion, and can withstand high temperatures. When it comes to creating complex stainless steel parts, two popular manufacturing processes are investment casting and CNC machining. Both methods have their pros and cons, and choosing the right process can greatly impact the quality, cost, and lead time of a project. In this article, we will compare stainless steel investment casting and CNC machining to help you determine which is better suited for your specific needs.
What is Stainless Steel Investment Casting?
Investment casting, also known as lost-wax casting, is a manufacturing process that involves creating a wax pattern of the desired part and then encasing it in a ceramic shell. The shell is then heated to melt the wax, leaving a hollow cavity that is filled with molten metal. After the metal has solidified, the ceramic shell is removed, and the finished part is ready for finishing operations.
Stainless steel investment casting is an ideal process for creating intricate parts with tight tolerances and fine surface finishes. It is also a cost-effective process for low to medium volume production runs. Additionally, investment casting can produce parts with complex shapes that are difficult or impossible to machine.
Advantages of Stainless Steel Investment Casting
- Complex Shapes: Investment casting can produce parts with intricate shapes, such as thin walls, internal cavities, and undercuts, that are challenging or impossible to create with CNC machining.
- Fine Surface Finish: The investment casting process produces parts with excellent surface finish and dimensional accuracy. The surface of the part can be further refined through various finishing processes, such as polishing, buffing, and electroplating.
- Low Tooling Cost: Investment casting requires minimal tooling, which results in lower tooling costs compared to other manufacturing processes.
- Wide Material Selection: Stainless steel investment casting can use a wide range of materials, including various grades of stainless steel.
Disadvantages of Stainless Steel Investment Casting
- Longer Lead Times: Investment casting requires several steps, including wax pattern creation, ceramic shell casting, metal casting, and finishing. This can result in longer lead times compared to other processes.
- Higher Per-Part Cost: Investment casting can be cost-effective for low to medium volume production runs. However, the per-part cost can be higher than CNC machining for high volume production runs.
- Limited Part Size: Investment casting is not suitable for large parts, as it is challenging to create large ceramic shells and cast large volumes of metal.
What is CNC Machining?
CNC machining, or computer numerical control machining, is a manufacturing process that involves using a computer-controlled machine to remove material from a solid block of material to create the desired shape. The machine tool, such as a milling machine or lathe, uses a series of cutting tools to shape the material into the desired geometry. CNC machining is commonly used to create complex parts with high precision and accuracy.
Advantages of CNC Machining
- High Precision: CNC machining can produce parts with high accuracy and repeatability, making it suitable for creating parts with tight tolerances.
- Short Lead Times: CNC machining can produce parts quickly, as the process does not require creating a mold or pattern.
- Lower Per-Part Cost: CNC machining can be more cost-effective than investment casting for high volume production runs.
- Large Part Size: CNC machining is suitable for creating large parts, as the size of the part is only limited by the size of the machine tool.
- Surface Finish: The surface finish of a part created through CNC machining is better than the surface finish achieved through investment casting.
Disadvantages of CNC Machining
- Limited Shapes: CNC machining is limited to creating parts with certain shapes and geometries that can be achieved with cutting tools. It is challenging to create parts with thin walls, internal cavities, and undercuts with CNC machining.
- Tooling Costs: CNC machining requires the use of expensive tooling, such as cutting tools and fixtures, which can result in higher tooling costs compared to investment casting.
- Material Selection: CNC machining is limited to certain materials that can be machined easily, such as 304 and 316 stainless steel.
Stainless Steel Investment Casting vs. CNC Machining: Which is Better?
Choosing between stainless steel investment casting and CNC machining depends on the specific requirements of a project. If the part requires complex shapes, large volume, investment casting may be the better choice. Investment casting is also more cost-effective for low to medium volume production runs.
On the other hand, if the part requires high precision and accuracy, and the project involves a low production run, CNC machining may be the better choice. CNC machining is also suitable for creating large parts and parts with simpler geometries.
Anyway, It is essential to consider the lead time, per-part cost, material selection, and surface finish requirements when choosing between investment casting and CNC machining. The decision can greatly impact the success of the project, and it is crucial to work with a reliable and experienced manufacturing partner that can provide guidance on the best process for your specific needs.
CFS Foundry has the capabilities of both stainless steel investment casting and CNC machining, we can help you to select a suitable manufacturing method for your project. Any inquiry on stainless steel investment casting or CNC machining item, pls feel free to contact us!