Low pressure casting is a very excellent casting process, with the development of continuous it has realized mechanization, automation production, it is of great significance to improve the production efficiency and yield.But the technology is not is ideal for all casting workpiece, such as wheel casting, can produce different defects due to various factors.Low pressure casting wheel hub is one of the most common defects cracks, especially in the area of stress concentration, cold cracking and cracking are two very common phenomenon.When casting cooling to the low temperature effect on casting casting stress intensity will be more than the casting itself or plastic, prompting the cracks.And materials in the process of solidification, due to the effect of heat transfer of the type of wall, starting from the surface of solidification and casting in solid-state contraction.At this time, when there is obstruction of the contraction of dendrite layer, interdendritic will be opened and thermal cracking.Except process factors on the structure of the wheel hub design, process parameters, such as mold temperature will also cause the occurrence of such problems, but improve casting technology can't completely solve so, need to improve the design of wheel structure at the same time, proper improve mold problems at the same time, and to ensure that the workpiece through the reasonable lift system of casting molding.