What is the types of patterns in casting？
According to Wikipedia’s explanation, a Pattern is a copy of the object to be cast. In this order, pattern shapes molds, and molds make metal parts. So the pattern is very critical to the final part. There are different types of patterns in casting. But we can divide them into two types:
- Reusable： types of pattern in sand casting or plaster. They can leave marks in many molds.
- Consumable： types of pattern for investment casting. We will destroy the model before casting it.
For all types of patterns in casting, it is not only a problem of shaping the cavity but also a scientific feeding system and demoulding method.
12 Different types of patterns in casting
For a long time, foundry workers regarded types of patterns in casting as the most cumbersome step in operation. Nevertheless, the pattern is still an indispensable tool in the casting process. Since casting patterns directly affect the final product effect, patterns play a vital role in casting.
When making different types of patterns, they should always be larger than the size of the casting. And they must be able to withstand rough handling. In addition, casting patterns can be made of metals, such as aluminum, brass, gypsum, and wax.
So how do you choose the right type of pattern in the manufacturing process? There are a few things you need to consider. They are the number of castings, the size and complexity of their shapes and sizes; the type of molding and casting method to be used; machining operations, and characteristics.
Take a look at 12 different types of patterns in foundry
- Single Piece Pattern
- Two-Piece or Split Pattern
- Multipiece Pattern
- Match Plate Pattern
- Gated Pattern
- Sweep Pattern
- Loose Piece Pattern
- Skeleton Pattern
- Shell Pattern
- Segmental Pattern
Single Piece Pattern
What is a Single Piece Pattern? It is also called a solid pattern and is the lowest cost type of pattern in casting. Single Piece Pattern is very suitable for simple crafts, small batch production, and large castings. Because this casting pattern only needs a simple shape, a flat surface like a rectangular block. If there is no such flat surface, pattern forming will become a difficult task. It is expected that it will be in a state of coping or dragging down.
Two-Piece or Split Pattern
This pattern has a parting surface. The parting surface can be flat or irregular, and the casting shape determines the exact position. Generally speaking, there are two sliced patterns. One of the parts is formed by drag mold, and the upper mold forms the other. In addition, the upper part always has positioning pins. Using positioning pins, we can align the two halves of the split pattern.
For complex designs that are difficult to make, Multipiece Pattern is a good solution. It includes three or more patterns, which can help you realize the production of casting molds. For example, if we consider the three-piece pattern. It is composed of the top, bottom, and middle parts. The bottom part is dragging, the top part is coping, and the middle is called the check box.
Match Plate Pattern
Usually, the matching plate pattern has a metal plate. Its function is to divide the upper and lower areas into opposite sides of the board. This casting pattern is almost effortless and can provide accuracy and high yield. Therefore, we use it in manufacturing and aluminum and other metal castings. But it has a drawback. It is costly. For match plate patterns, you can choose according to your needs.
Do you know? We use one or more patterns to form a molding gate pattern. It is designed for molds that can manufacture multiple parts in one casting process. A gated pattern combines different structures so that the molten material has flow channels. When the door and the runner are connected, the pattern will loosen. Due to their high cost, they are used to make small castings. The small castings are then further used in the molding machine and mass production process.
We believe that Sweep Pattern is large and is a good choice for castings with simple shapes. But you should note that this kind of casting mold is expensive and not very versatile. Therefore, from an economic point of view, it is not the best choice. It is very effective if you use it to remove excess sand. If you want to use this casting pattern, you should highlight the wooden frame when casting. Basically, we apply sweep patterns widely in the pit or ground welding industry.
In the sweep pattern, we usually use wooden boards. The method is to rotate the plank along an edge to create a circular or rotationally symmetrical cavity. Observe carefully, and the sweep is composed of three parts: the main shaft, the base, and the sweep. In this way, the casting pattern will form a cavity in the vertical direction. You will find sand attached to its base, and these sands also form the shape of a casting in a short time. Sweep Pattern is usually used when we have to create a projection in a short time interval. With Sweep Pattern, you can easily make a large number of symmetrical casting molds.
Loose Piece Pattern
Loose Piece Pattern has a significant advantage. It can help the manufacturer to take out a solid pattern above or below the parting surface with protruding parts from the mold. However, this pattern requires additional skilled labor, so it is an expensive casting pattern in castings. In addition, the movement of the Loose Piece Pattern can be completed due to the punching process.
Cope and Drag Pattern
As the name suggests, Drag Pattern consists of two independent boards. Its two parts can be formed on the mold box separately. After forming the parts, the two separate pieces are combined to form the entire cavity. Its pattern is somewhat similar to the Two-Piece Pattern. We usually use Cope and Drag Pattern to produce large castings. That’s because the mold is very heavy and inconvenient for users to use.
Shell patterns are a good choice for creating hollow-shaped structures. In fact, we also use it in this way. Like this, complete its separation process along the center. We use pins to fix the two halves produced after separation. This type of pattern in the manufacturing process is usually made of metal and mounted aboard. For example, it is like a split pattern. One half of the pattern is placed on the top of the plate, and the other half is placed on the bottom of the plate.
Follow Board Pattern
Follow Board Pattern consists of a simple board tool, which has many uses. We can say that it is the basis of the molding process. First, we mold it in one place, then rotate the pattern to the next part to complete the molding again. These types of pattern in the foundry is used in the casting process where the structure is weak and may break after applying force. In other words, when we need to cast products in the shape of a large circle. The completion of the final product requires repeated use of these steps.
It is just similar to Sweep Pattern. It is because their working structure is almost similar. As the name suggests, Segmental Pattern is a segmented form. We use it for molded circular structures. It can be found that there is a complete rotation in Sweep Pattern, but there is no full rotation in segmented mode. We can partially rotate for the mold shape or structure required by design to obtain the desired output. That is, to create a mold, we need to use part of the pattern.
Again, the type of pattern in foundry directly affects the final product. Therefore, in the casting process, the patterns are the decisive factors for the quality of the mold and castings. So the importance of types of patterns in the foundry is self-evident. We suggest that you should consider some factors when choosing the types of patterns in casting. For example, the size and shape of your casting products to choose the best solution for your casting business.