Below is a list of Expanded Metal Grating manufacturers from Rancho Cucamonga, California. Expanded metal grating is a framework of metal mesh created through a single metallurgical operation for use in industrial, commercial and residential settings as a covering or textured surface. Though several other processes, such as welding and perforation, are commonly used to produce grates, metal expansion is a singular operation that produces rigid, non-raveling metal shapes and surfaces.