With the widespread use of aluminum alloy wheels with light weight, good heat dissipation, energy saving, and beautiful appearance allover the world, cast aluminum wheels have become a common choice, and low-pressure cast aluminum wheels are good for large-scale production due to their good quality and high efficiency, which has become the mainstream. A very critical component in low-pressure casting technology is the riser tube. Each casting is formed by the riser tube. Under the action of air pressure, the melt liquid at the bottom of the furnace rises to the upper mold. After the casting is cooled and formed, the pressure is released to make the uncondensed melt liquid in the riser tube return to the lower molten pool. In continuous production, the riser tube has to repeatedly receive the impact of changes in air pressure and the impact of cold and hot melt flow up and down. At this time, the riser tube must not have any air leakage, and long-term soaking and scouring at high temperature cannot cause obvious erosion or peeling of the riser tube. Being able to withstand such harsh conditions and a life span of at least one month is a requirement that the riser tube must meet.

Before 2000, most of aluminum wheel factories used iron for riser tube, and do coating on iron riser tube. But the iron riser tube will contaminate the molten liquid during use, which will cause the composition to increase iron, which will make the mechanical properties of the aluminum wheel worse, and there are hidden dangers or even scrap. Frequent shutdowns to paint the iron riser tube are also not conducive to the stability and production of product quality. The ability to produce riser tubes that meet the requirements has been a major issue in the production of aluminum wheels.

The riser tube is one of the key parts of the aluminum alloy low-pressure casting machine such as the cylinders and wheels of automobiles and motorcycles. When working, the lower end is placed in a low-pressure casting furnace for holding aluminum melt, and the upper end is connected to the low-pressure casting mold inlet. The melt rises along the riser tube into the mold cavity by pressure. Complete casting periodically to realize casting automation and continuous pressure, fill the mold from bottom to top with molten metal, combine the runner and the feeding channel into one under low air pressure, and always maintain the same temperature gradient and pressure gradient of the mold. It solves the contradiction between heavy-duty stability and feeding in gravity casting, and greatly improves the quality of castings. Low pressure casting has a higher feeding pressure and temperature gradient, which effectively improves the compactness of thick and large section castings. This technology is still used in the casting of thick and large section castings.  Due to the high quality requirements of automobile wheels, their structure is suitable for low-pressure casting, and the demand is large, which greatly promotes the development of low-pressure casting technology.

Since the beginning of the research and application of low-pressure casting technology in the early 20th century, low-pressure casting has been transferred from trials to production, from production of simple parts to that of complex parts, from the production of aluminum and steel alloy castings to lightweight magnesium alloy castings. The development of parts and small batches to mass, mechanized production, and the development of higher precision low-pressure casting such as metal molds and mold elimination from sand molds. In recent years, casting technology is developing towards lighter, thinner, more refined, stronger, tougher, lower cost, shorter cycle, and higher quality. Large-scale, lightweight, precise, digitized, networked, clean, and recycling will be the important development direction of casting technology in the future.

Die casting machine is a series of industrial casting machinery that hydraulically inject molten metal into a mold under pressure to cool and form, and obtain solid metal castings after opening the mold. It was originally used for die casting type. With the advancement of science and technology and industrial production, especially with the development of automobile and motorcycle industry, household appliances, taking energy saving into considering, die casting technology has been rapid development.