Casting is a widely popular process of manufacturing used in various industrial applications owing to its overall performance, affordability, and adaptability. The two most widely used methods are die and sand-casting. There have been quite a few arguments regarding which of the two methods is the better choice as both have advantages and disadvantages.
An overview of die-casting
The die casting manufacturing method requires using a metal die that determines the final configuration of the product. The process is synonymous with extremely high pressures and temperatures. In the casting process molten liquid metal is injected into a metal mold. The molten metal experiences a gradual reduction in temperature as it cools and solidifies when it is left idle over a stipulated period of time.
Once the product has been made, the item is removed from its mould and the same mould is prepared to receive a new batch. It is a relatively speedy process and production time ranges from seconds to minutes depending on factors like overall weight, shape, and dimensions of the end product.
In die-casting, the mould can be re-utilised to produce multiple products and doesn’t need to be reshaped or destroyed after use. This is considered to be one of the most important selling points of the process. Further, the manufacturing speed and ability to mass-produce high-quality complex parts make die-casting the preferred choice in industries which rely on the production of parts in a high-momentum environment.
An overview of sand-casting
There are minor differences between die casting and sand casting. While both processes involve the use of molten metal to be shaped into their configurations, molds in the sand casting process are made from sand and not metal. Sand-casting molds are formed by placing a unique pattern in a sand filled casing which is then compacted using force around that object to obtain a specified shape. When the pattern is removed, a cavity is formed in the packed sand into which molten metal is poured with the help of gravity and allowed to cool and solidify. Lastly, the cast is ejected from the sand mold and brushed to remove excess sand.
The mould utilised in sand casting requires preparation of approximately 10 minutes before it can be used. In contrast, die-casting moulds are usable immediately. This makes sand-casting a lengthier process compared to die-casting when manufacturing requirements demand speed. On the other hand, sand-casting is comparatively cost-effective and adaptable which makes the process the ideal choice for alloys and unique shapes. It is also very simple to implement.
What are the key differences between sand casting and die casting?
There are significant differences between both manufacturing methods. They are briefly explained below:
- Mould material: As discussed earlier, the materials used in making the moulds in both processes are significantly different. Die-casting moulds are made entirely from metal whereas the sand-casting counterparts are made using sand. As a result, products made using die-casting are more durable owing to the increased amounts of pressure used during the process. This pressure is beneficial as it prevents gap formation and any defects occurring inside the product.
- The complexity of manufactured parts: Die-casting and sand-casting also differ in terms of the final complexity of manufactured parts. Both processes can create complex parts and components but die-casting enjoys an upper hand in terms of dimensional accuracy and manufacturing speed. Further, pressure injection in die-casting allows for the creation of parts and components with relatively thin walls.
- Wall thickness of manufactured parts: As mentioned above, die-casting produces components with comparatively thinner walls when compared with sand-casting. While this attribute ensures higher dimensional accuracy, the sand-casting process allows products to be corrected and fine-tuned through post-processing as they have thicker walls. As a result, sand-casting isn’t a preferred choice for small components.
- Production volumes: Sand-casting has relatively simple tooling requirements and takes very little time at the start. In contrast, die-casting has a more complex and time consuming tooling requirement. However, die-casting compensates for this by being quicker in manufacturing large volumes of the same product.
- Finishing of product surface: As the sand casting method utilises a mould made of sand, the final finish of the product is relatively coarse and rough. Additional machining and processing are required in most cases after the product is removed from the mould. Products manufactured using die-casting have a smooth finish and rarely require any post-processing.
- Process cost: Moulds used in sand-casting are significantly cheaper since die-casting uses metal moulds and more expensive and complex to make, adding to the final die casting cost.
- Use cases: Die-casting is the ideal process to make intricate components for medical devices and small electrical components. Sand-casting is primarily used to produce furniture and large engine components like engine blocks in the automotive industry.
Which process is the better option?
At the end of the day, the choice of processes depends entirely on the product requirements. Both processes are ideal in different use cases and excel at producing components and products with differing characteristics. While die-casting is more suited to large-scale manufacturing of intricate components, it is fairly expensive to set up as compared to sand-casting. Therefore, the production requirements must be evaluated before making a choice.