High Quality Customized Gravity Cast - ODM Casting Service Supplier JWHEEL for Car Wheel The JWHEEL alloy wheel companies have been focusing on quality, management and environmental protection, and has passed ISO 9001:2015, IATF 16949, Germany KBA, Japan VIA association certification (laboratory certification).Gravity casting is a method of manufacturing a cast wheel of an specific metal alloy, typically aluminum, although Magnesium is also used, which involves supplying molten metal to a mould cavity via a feeder through a running system where the molten metal entry point is located above the top of the mould cavity. In this manufacturing process all the metal entering the mould is subject to turbulence. This turbulence can cause severe defects such as oxide inclusions and entrapped gas porosity and in some cases mould erosion and hotspots.