Investment casting and sand casting are both included in the casting manufacturing method and have a long history that can date back to 1838. Though both of the two casting methods are making metal parts by pouring the molten metal into a mold, there are significant differences between them. This article will explain all the differences between them. Only 5 minutes, you will find the right choice for your casting manufacturing with the basic information of them.
What Is Investment Casting?
Investment casting manufacturers create a wax pattern to create the void for producing metal parts. The ceramic shell was built around the wax patter, and when it was hard enough, manufacturers will remove the wax pattern inside from the shell. Then pour the molten metal into the shell, allow it solidify. Final investment casting parts will have a smooth surface and the same shape with the wax pattern. Besides, the removed wax can be reused next time.
What Is Sand Casting?
Sand casting compacts sand around a pattern of a model of the final product. to create a sand mold. Most of the time, manufacturers mix the sand with clay and moistened with water to made the mold tough. One sand mold just can use one time, while the sand can be reused. The sand mold was mad by two halves, and when it used for casting, the two halves will be fastened closely.
Investment Casting VS. Sand Casting
Though both the investment casting and sand casting are included in casting technology, to be precise, there are significant differences between them from the process, metal material, size, surface finish, and cost.
5 Differences Between Investment Casting And Sand Casting
Generally speaking, investment casting process has 8 main processes.
- Creating a wax pattern
- Wax tree assembly
- Shell building
- Wax removing
- Metal pouring
- Shell knock off
- Cut off the parts
- Individual casting
Liquid wax build complex geometries, just need one reusable mold. When the wax solidified and put into the liquid ceramic for a shell, the entire shape will be dipped. Therefore the ceramic shell it made nearly included all details that the wax pattern has. And the design of the wax pattern should according to the final products.
6 main sand casting processes.
- Create a mold pattern in sand
- Set up the gating system
- Remove the mold pattern
- Pour molten metal in to mold void
- Metal solidification
- Remove the metal casting
Mold pattern was made before the sand casting beginning, and the pattern can be used in the next mold making. And the sand mold can be used at one time. When you finished the metal casting, the sand mold will be destroyed.
Factor metal material tolerance, melting point and other features, casting manufacturers should consider material selection when they are creating casting business. If you want to cast non-ferrous metals like aluminum, and magnesium, the investment casting can able to finish the casting process. For sand casting, it also has its own suitable casting alloy, though there may some materials that the investment casting can also make.
There is a list of casting material selection:
Sand casting: iron, steel, bronze, brass, aluminum, magnesium, and other non-ferrous alloys.
Investment casting: stainless-steel alloys, brass, aluminum, carbon tell.
Size and Weight
Generally speaking, the metal parts that investment casting and sand casting made have a difference in size and weight.
Investment casting: It has a wax pattern made from mold by injecting the wax, and this kind of part allows more fine details. When the pattern dipped into a liquid ceramic for building a shell, the details have been retained as much as possible. Therefore, investment casting can be sued at more precise, complex, and small metal parts casting. There is a very little limitation of the size and weight of investment casting.
Sand casting: It needs a mold pattern to create a mold cavity. Sand casting can not often cast the small, complex metal parts as investment casting. Molding larger parts with sand casting may have a good effect.
Investment casting provides a smooth, finished surface for metal parts. While because of the two halves of the sand mold, the surface finish of it will have a seam left by the parting lines in the mold. Besides, the sand mold has a relatively rough inside, for the final casting surface finish of the metal part will have an equally rough surface.
Investment casting has an expensive pre-production cost to prepare a wax patter, ceramic shell and finally makes smooth finished products. While sand casting has a lower cost than investment casting, it needs an after the process to deal with the rough surface of the final product.
4 Aspects You Should Consider for Casting Manufacturing
If you want to create a casting business, choose the right casting method is a very important step to achieve success. There are 5 aspects you should consider for casting manufacturing.
Before considering this aspect, you should think about factors. What are the most suitable materials for your products, which casting methods better for it? Materials tolerance, and melting point and other features should be included in.
You should consider the payback period of casting tool cost, find the balance between the income and expense. Investment casting may have an expensive tool to spend, while the sand casting has lower cost at the casting tool.
Both of investment casting and sand casting can achieve mass production, while they have very different cycle time. Sand casting may need a long time to produce, and other time to deal with the rough surface. While investment casting provide a quick production process, and shot cycle time with no after-process products.
If the cycle time of production occupies a very important part of the cost, another factor you should consider is the real cost. Investment casting has a short cycle time and has no other extra time and cost for producing. Investment casting has to create other costs and time for rough product surface dealing.
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