Excuse me, what is the difference between the manufacturing process of die-casting engine and casting engine, and what are the benefits to the engine?

Gravity casting (commonly known as pouring) refers to the process that molten metal is injected into the mold under the action of gravity. Generalized gravity casting includes sand casting, metal casting, investment casting and clay casting. Gravity casting in a narrow sense refers to metal mold casting.

Die casting (die casting for short) refers to the process of injecting molten metal into the mold under the action of other external forces (excluding gravity). Pressure casting in a broad sense includes pressure casting, vacuum casting, low pressure casting and centrifugal casting of die casting machine. In a narrow sense, die casting refers to the die casting of the metal mold of the die casting machine.

Die-casting machine, die-casting alloy and die-casting mold are the three elements of die-casting production, and they are indispensable. The so-called die casting process is the organic comprehensive application of these three elements, so as to produce qualified castings with good appearance and internal quality, and the size meets the requirements of drawings or agreements, even high-quality castings stably, rhythmically and efficiently.

Die casting machines are divided into hot chamber die casting machines and cold chamber die casting machines. Hot chamber die casting machine has higher automation, less material loss and higher production efficiency than cold chamber die casting machine. However, due to the heat resistance of the parts, they can only be used for casting low melting point materials such as zinc alloy and magnesium alloy. Aluminum alloy die castings widely used today can only be produced on cold chamber die casting machine because of their high melting point.

The main feature of die casting is that molten metal fills the cavity at high pressure and high speed and forms and solidifies at high pressure. The disadvantage of die casting is that the air in the mold cavity is inevitably trapped in the casting during the high pressure and high speed mold filling process, forming subcutaneous pores, so aluminum alloy die casting is not suitable for heat treatment, and zinc alloy die casting is not suitable for surface spraying (but can be painted). Otherwise, when the pores in the casting are heated by the above treatment, the casting will be deformed or foamed due to thermal expansion. In addition, the machining allowance of die casting is smaller, generally about 0.5mm, which can not only reduce the weight of castings, reduce the machining capacity and reduce the cost, but also avoid penetrating the dense layer on the surface and exposing the subcutaneous pores, causing the workpiece to be scrapped.

Generally, aluminum alloy engine parts are die-cast. The tensile strength of the products produced by the same material die casting process is enhanced, and the comprehensive mechanical properties of the blank are significantly improved. In addition, the smoothness of the outer surface of the blank produced by this process reaches Grade 7 (Ra 1.6).

Gravity casting (pouring) is suitable for the manufacture of ferrous metals and large structural parts, and sand mold gravity casting is usually used. Sand casting has wide adaptability, including small pieces, large pieces, simple pieces and complex pieces, single pieces and large quantities. The molds used in sand casting are mostly wood, commonly known as wood molds. There are also aluminum alloy molds or resin molds with long service life. Although the price has increased, it is still much cheaper than die-casting metal molds, so the price advantage is particularly prominent in the production of small batches and large pieces. In addition, the fire resistance of sand mold is higher than that of metal mold, so this process is often used for materials with high melting point, such as copper alloy and ferrous metal. However, sand casting also has some disadvantages: because each sand mold can only be poured once, the mold will be damaged after obtaining the casting and must be reshaped, so the production efficiency of sand casting is low; Because the overall nature of sand is soft and porous, the dimensional accuracy of sand casting castings is low and the surface is rough.

For the engine, it doesn't matter what casting process is adopted. Usually, it is only in terms of appearance and structural weight that die casting has certain advantages in specific gravity casting (pouring). However, if different casting methods are chosen because of different materials, the structural appearance of the engine and the output power per unit weight of the engine will be very different, and the engine with die-casting structure has obvious advantages.

At present, the cylinder heads and cylinders of most passenger cars (cars) are aluminum alloy die castings, and a few cylinders are cast for engines with slightly backward technology (cast iron cylinders), while the engines of large cars are mostly cast iron.