Investment Casting vs. Sand Casting

Investment Casting and sand casting are two different metal casting methods of creating metal components both by pouring liquid metal into moulds. Because both investment casting and sand casting have their own benefits, so we can not say which is better, just for different application. As an investment casting manufacturer, we are often asked by our customers about the difference between investment casting and sand casting. Here is a article about the comparision of these two processes.

Investment Casting

Investment casting vs sand casting

Investment casting is a precision casting process using lost wax method to make components in any cast alloys. Mostly the mould or pattern of investment casting is made by aluminum. Investment casting process, also called lost wax casting, starts from creating a wax pattern (same dimensions as finished components) by injecting wax into casting mould. Then dipping the tree assembly into refractory slurry to form a ceramic shell. Finally pouring melton metal into the shell by sprue gate and cooling for solid casting blanks. Advantages of investment casting are:

  • Investment casting can achieve very thin walled parts with complex shapes.
  • Very accurate, even net shape with precise dimensional casting
  • Excellent surface finishes save machining and finishing.
  • Ferrous and nonferrous metals, as well as duplex alloys, can be used.
  • Investment casting can be quite economical over repeat runs.

Sand Casting

sand casting

Sand casting uses sand to creat a molding surface. A mold made of sand is somewhat flexible, so there’s less cracking, tearing or other types of flaws as the liquefied material cools and hardens. Advantages of sand casting are:

  • Sand casting can be lower cost particularly in shorter runs.
  • It can accommodate large castings.
  • Sand casting can also utilize both ferrous and non-ferrous metals.
  • The cost for post-casting tooling can be lower.

Differences Between Investment Casting & Sand Casting

Cost: Investment casting process always costs more than sand casting for the complexity and preparation needed.

Weight: Investment casting can make casting smaller than 1lb, while sand casting can not always make small and complex parts like investment casting. Investment casting also has limitations in the size and weight made in sand casting. The mold-handling equipment at the casting plant will effect the weight of products, Most U.S. and Eourpean facilities can only cast parts up to 20 lb. While our investment casting foundry in China can make investment castings up to 120lb.

Surface Finsh: Surface finish is another big difference between investment casting and sand casting. Investment casting can creat finished part showing smooth surfaces and low tolerances under the work of aluminum pattern. After removing the sprue gate and shot blasting, the casting blank is the final part for delivery. With sand casting, the mold has to be split apart to release the final product. As a result, parting line will left outside the finish part. And due to the rough sand, the surface of finished cast parts will be equally rough. So addtional cost and time will be required in
secondary machining for removing the partling line and more smooth surface.

Ease of design: In investment casting, ceramic shell mold is formed using liquid slurry, so parts by investment casting process can be made almost any shape, giving engineers extraordinary freedom in their designs to add intricate features and complex shapes. For sand casting parts, to come out the sand easily with less friction, they usually have to be tapered (with draft angles) or shaped. It’s also a challenge for sand casting to make parts with internal voids or cavities. Sand casting requires cores properly shaped and inserted in the mold to form the part’s interior. Sometimes, several cores may be needed, and it also cost time to form and secure them within each mold.

The investment casting process is often superior to other types of casting, particularly in regards to surface finishes. CFS foundry, a Chinese company, has over 20 years of experience creating ISO-certified investment castings in its factories. What’s more, we can also provide sand casting service if needed. We ensure your castings are flawless and dimensionally correct by using magnetic particle inspection, high-accuracy machining and CMM. Contact us today if you have a RFQ for cast part.

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