Sand Casting is one of the oldest metal casting processes, dating back to 1000 BC. The process uses expendable sand molds to form intricate metal parts of various shapes and sizes at a relatively low cost. The process involves the use of molten metal, a furnace, a sand mold and a pattern. The metal is melted in the furnace, poured into the cavity of the sand mold, and then formed into shape by the pattern.
After the metal solidifies, the casting is removed from the mold. This process is so popular that more than 50% of all metal casting products are made only using sand casting.
Sand casting manufacturers produce a wide range of castings, with a variety of different sizes and weights ranging from a few grams to many tons.
Furthermore, different sand casting materials and methods can be used, including resin sand casting and green sand casting. Smaller casting parts include pulleys, connecting rods, crankshafts and gears, whereas larger sand casting parts include engine blocks, transmission cases, cylinder heads and engine manifolds.
The process consists of six main steps:
Make a reusable pattern that has the same shape as the final product. Leave a small allowance to accommodate for thermal shrinkage. Patterns can be made from different materials, depending upon the number of sand casting tolerances we want to include.
After making the pattern, a sand mold is created by placing the pattern inside the sand blocks.
The mold is generally shaped in two halves: the upper half is called the cope and the lower half is called the drag. Once the sand tightly holds up, the two halves are separated, and the pattern is removed. Then the two halves are joined back together, leaving a cavity with the same shape as the pattern.
In the next step, molten metal is poured into the mold cavity. The molten metal fills the cavity, as well as the runner and riser pathways.
Once the metal cools, shake up the sand block, allowing the solidified metal product to fall out. Most of the sand is recovered and reused for further casting. Gates, runners, and risers are separated from the casting part, and other post-casting processes such as machining and grinding are applied for the final size and surface finish.
Over 60% of all metal castings are produced via sand casting. The greatest advantage of using this casting method is its versatility. The process can produce castings of various sizes, from a few ounces to many tons, and can easily handle different shapes and designs (with proper casting engineering).
Additionally, this process allows for the greatest flexibility in material choice; most metals, including special steel and various alloys, can be used in this process. Combined with inexpensive tooling and relatively straightforward casting operation, it is an easy go-to method for producing most metal castings.
Combined with inexpensive tooling and relatively straightforward casting operation, it is an easy go-to method for producing most metal castings. However, sand casting is also prone to porosity and other defects.
It is so much more than just pouring molten metal into a mold. It takes years of experience to get the process right.
Typical | Feasible | |
|---|---|---|
Materials | Cast iron Carbon steel Alloy steel Stainless steel Nickel Magnesium Copper Aluminum | Zinc Titanium Lead Tin |
Quantity | 1-1000 | 1-1000000 |
Tolerance | ±0.03 in | ±0.015 in |
Surface finish | 200-700 µin | 100-2000 µin |
Max. Wall Thickness | 0.120-6 in | 0.08- 45 in |
Part size | Few ounces- 500 ton | Few ounces- 500 ton |
Shapes |
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As a World-Class Manufacturing and Engineering company, Omnidex specializes in high-quality porosity-free castings, including a heavy-duty supersized casting that is trusted by the leading mining companies around the world.
As experts in sand casting, we understand your concerns about casting quality. That is why we strictly follow a series of Industry Best Practices to prevent shrinking defects and porosity and to ensure that the quality of our sand cast products is always up to our highest standards.
All of our casting patterns are CNC machined with specialised equipment. Accuracy is paramount at this stage as any inaccuracy in the pattern will produce inaccurate castings later on in the process.
Every casting design has to go through a series of simulation tests. These tests allow our engineers to estimate the likelihood of porosity, so they can move, increase or decrease the feeds and uprisers, or add chill blocks as required.
Our process is supervised by our highly experienced sand casting specialists. We will take into account the metal flow in the sand mold, material cooling, and other issues.
Such as uneven shrinkage or surface distortion, in order to produce castings of the highest quality possible.
Our engineering team will take into account all shrinkage allowances, draft angles, and other factors when designing the mold. Placement of removable cores, feeds, uprisers and chill blocks are also carefully thought out, allowing us to produce the perfect results.
Ferrous castings are pre-treated with zinc phosphate which provides a high level of corrosion protection, and are finished with anti-rust coatings, zinc plating, powder coatings or spray painting.
sand casting foundry
sand casting foundry
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If you are looking for metal casting services, our brochure is a great way to discover what Omnidex has to offer. You can download HERE to learn more.
