... are needed at high volumes or when better tolerances and surface finish are required than can be achieved by gravity ... casting, sand casting, gravity casting, low pressure casting), 3.welding, (optional) 4.surface treatment, (optional) 5.assembly, (optional)6.QC and ... be done by forging or extrusion, 2.machining, 3.welding, (optional) 4.surface treatment, (optional)5.assembly, (optional)6.QC and ...