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2022.1.18
The lost foam casting process is a globally recognized near-net-shape process, which can reduce the cost by integrating integrated casting design and lightweight design. Although the lost foam casting process is not widely used as sand, metal mold, or die casting process, it has its unique advantages in using precision molds to produce castings with complex shapes. Why choose lost foam casting? What are its advantages compared with other casting technologies?
Lost Foam Casting (LFC) is a new type of casting method that combines the wax or foam model that is similar to the size and shape of the casting to form a cluster of models, brushing fire-resistant paint and drying it, then embedded in dry quartz sand in the vibration modeling, pouring under negative pressure, making the model gasified, liquid metal occupy the model position, and solidified and cooled to form a new casting method.
Lost foam casting technology can easily enter a new market. Compared with the casting design of other casting processes, such as sand casting, there are many idle parts. Because most casting processes require reusable molds or plates that can be removed from the sand mold before pouring. This needs to be taken into account when designing the layout structure of the mold or template of the product. On the contrary, in the lost foam casting process, the foam model retained in the sand mold does not need to be removed and the gasification is lost in the casting process, which eliminates many limitations for the structural design of the product.
In the lost foam casting process, EPS or copolymers are foamed in the aluminum alloy mold, and then a foam die is obtained, and then bonded into a complete foam model. The corresponding gating system is then formed into a die string. Dip coating, drying, put it into the sandbox, add dry sand without any binder and vibrate it. After pouring the metal liquid into the foam model, the required casting is obtained. With the advantage of foam bonding in lost foam casting, it is possible to achieve weight reduction, the direct casting of inserts, and the integration of multiple parts. Moreover, it can realize castings with complex shapes that can not be imagined by other casting processes. For example, engineers can use designs with little or no draft angle to achieve more uniform wall thickness and better surface finish on castings.
Although the cost of the lost foam casting process is higher than other processes, it will reduce the cost as a whole over time. For example, considering the saving of labor cost in casting and machining processes, as well as the saving of mold cost, etc.
Compared with other casting processes, the lost foam casting process has its unique advantages.
1. Freedom of design. The lost foam casting process can freely design castings with complex cavities. This kind of castings is difficult or impossible to achieve by using other casting processes, which is the biggest attraction for many users who choose the lost foam casting process. This is very useful for the integrated design of components to eliminate subsequent cleaning, grinding, and machining processes.
2. Suits complex or simple shapes. The lost foam casting process does not necessarily have to play an advantage in complex products. For example, a part with a drain port in a very simple shape was originally produced by the sand casting process, and the drain port was formed by the sand mold. This product has a problem in processing. The scrap rate caused by the blockage of the oil drain can not be raised. After it is converted to the lost foam casting process, this problem is solved, and its production cost is lower than that of sand casting.
3. Technological benefits. In addition to the advantages in design, lost foam casting has advantages in technology. A typically lost foam casting production line is usually only about 30 meters long. This rather compact and usually highly automated process is very suitable for the mass production of a single product. Moreover, the process control is relatively simple.
4. Saves energy, improves productivity. Compared with the benchmark of sand casting, the lost foam casting process is more energy-saving, improves labor productivity and material utilization, reduces inventory, reduces scrap rate, and improves safety. lost foam casting molds can be used 400000-750000 times. In the lost foam casting cast iron factory, the delivery time is usually 4 weeks, because the foam model can be stored for a long time, and the mold string will be used as follow. Sand cores and sand molds do not need to be produced in advance for standby.
5. Reduce cost. These advantages in technology bring advantages in production cost. The service life of the lost foam casting mold is longer, the labor cost is lower, and the molding sand has no binder, which is convenient for recycling and reuse, so as to eliminate the problem of recycling the molding sand. In the later stage of lost foam casting, only the pouring riser can be removed, and there is no flash and burr, so as to reduce the workload of grinding and save the cost.
6. Improves casting quality. In the lost foam casting process, there are no defects brought by the binder, long-term repeatability, no sand mold defects, no risk of the wrong box, small dimensional tolerance of castings, excellent casting surface, improved the qualified rate of pressed parts, and so on, which all improve the quality of castings.