Jan. 18, 2022
Achieving consistently good results by sand casting is a complex process. Did you know, for instance, that three different kinds of sand are used in sand casting? Why is a particular type of sand used at what time? When should each type of sand be used?
We will discuss the three types of sand that are commonly used in sand casting, their usage, as well as the why's and when's of the different types.
Non-ferrous alloy casts are commonly produced through sand casting, also known as sand mold casting. The origins of this process date back more than 6,000 years, and it has undergone a number of changes and modernizations over the centuries. Nonetheless, the basic principles have not changed. There have been numerous replications of this technique in everything from small DIY shops to large commercial foundries. There are many variations of this process, but one of the main differences is the type of sand used. Here, you’ll discover the types of sand used in sand casting.
Green sand is made by molding wet sand which can also be termed clay. When the metal is being poured, the sand mold is uncured. Using green sand for casting is quick and economical, as the sand can be reused. However, the sand is soft, meaning that if that mold collapses or shifts during casting, the cast will be useless. Even so, the process has proven reliable enough to last for centuries and it remains in wide use today.
Advantages of Green Sand in Casting
Green sand is one of the most cost-effective materials to mold.
Mold is less likely to grow from heat-torn material.
Due to the fact that green sand has not been baked, it will deform less in the course of molding.
Disadvantages of Green Sand in Casting
Green sand is usually not smooth, in other words, it is rough and crude.
With an increase in weight, the surface gloss of products made from green sand will be damaged.
Having a soft texture leads to casting defects like sand leftovers and sand holes.
Mixing resin sand and heating the surface produces a solid mold with a smooth surface. Castings from a solid mold are less likely to produce defects, but they also cost more and take longer to produce. Unlike green sand molds, resin sand molds require more time, since each of them must be mixed and burned to produce the perfect mold. In addition to its high cost, resin sand must constantly be replaced, despite its ability for re-use. Therefore, the process tends to be more expensive.
Advantages of Resin Sand
Sand made from resin has excellent fluidity and compaction properties. It is possible to adjust the time of ejection using the above feature.
Resin sand becomes extremely strong after hardening. In this way, the resin sand will be less likely to be deformed in the casting process.
Disadvantages of Resin Sand
When resin sand is molded and cast, it releases an irritating odor.
Compared to green sand, resin sand is significantly more expensive.
Mold castings can be created using sodium silicate as well. By passing carbon dioxide through Sodium Silicate, it quickly turns from a liquid into a solid. This leads to sodium silicate dehydrating. It is particularly useful when castings need a cavity within them. In general, it can be mixed with other materials to create a solid core but must be mixed with other materials, so it can break down upon casting so the core can be removed. An incorrect mixture will result in the core becoming lodged inside the casting, making the casting defective.
Advantages of Sodium Silicate in Casting
It is non-toxic, colorless, and odorless.
During casting, it will not emit gases that are irritating or harmful.
No black or acid pollution is produced by sodium silicate.
Disadvantages of Sodium Silicate in Casting
It is difficult to collapse or separate.
Reclaiming the material from the waste is difficult. In addition, the water glass will cause pollution if it is not handled correctly.
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