Die casting is a manufacturing technique that produces complex-shaped metal parts using reusable molds, called die casting dies. The process requires a furnace, metal, a die casting machine, and the die casting die itself. Typically, nonferrous alloys such as aluminum or zinc are melted in a furnace and then injected into the die casting die by the die casting machine. There are two main types of die casting machines: hot chamber machines, which are suitable for alloys with lower melting points (such as zinc), and cold chamber machines, which are suitable for alloys with higher melting points (such as aluminum). The differences between these machines are explained in detail in the Equipment and Tooling section. Regardless of the type of machine, once the molten metal is injected into the die casting die, it quickly cools and solidifies into a finished product (called a casting). The next section provides more details on this process.
Castings produced by this method vary greatly in size and weight, ranging from a few ounces to 100 pounds. A common use for die castings is to make housings - thin-walled housings that often contain many ribs and bosses on the inside. Many metal housings for various electrical appliances and equipment are manufactured by die casting. In addition, a variety of automotive parts such as pistons, cylinder heads and engine blocks are also produced using this technology. Other items that are often die-cast include propellers, gears, bushings, pumps and valves.
Injection molding is the main manufacturing process for making plastic parts. This method is used to produce a variety of products with different sizes, complexities and application ranges. The injection molding process requires an injection molding machine, plastic raw materials and molds. In this process, the plastic is melted in the injection molding machine, then injected into the mold, cooled and solidified into the final product.
First of all, the die casting process is usually used for metal materials, such as aluminum alloys and zinc alloys, while injection molding uses plastics, such as ABS and PC. The difference in materials directly affects the application field. Die-cast products may focus more on strength and high temperature resistance, such as automotive parts and hardware tools. Injection molded products may be lighter and have good insulation, such as daily necessities and electronic housings.
Then, consider the structural complexity of the product. Injection molding can handle more complex shapes and fine details because plastics flow better in the mold and can make thin-walled structures. Die casting may have a relatively simple structure because the fluidity of metal is not as good as that of molten plastic. However, high-pressure die casting can also make complex parts, but the cost may be higher.
In terms of production cycle and cost, die casting molds are expensive and suitable for mass production, while injection molding molds are relatively cheaper, but also suitable for mass production. For small batches, injection molding may be more flexible? However, 3D printing may also affect the choice now.
Surface treatment is also a point. Die castings may require more post-processing, such as deburring and electroplating, while injection moldings can be directly colored and have a smoother surface. Users may be concerned about the appearance requirements of the product.
In terms of application areas, die casting is mostly used in automobiles and industrial equipment, while injection molding is common in home appliances, electronic products, and medical devices.
Strength and weight should also be considered. Metal die castings are heavier but stronger, while plastic injection moldings are light but may not be strong enough. If the user’s product needs to bear weight or be resistant to high temperatures, die casting is more suitable; if it needs to be light or insulated, injection molding is better.
In addition, cost factors, the initial mold cost of die casting is high, but the cost per piece may be reduced in large quantities. Although injection molding molds are expensive, the material cost is low and it is suitable for mass production of plastic parts. Small batches may be more cost-effective using other methods.