Abstract: This invention relates to an improvement in the process of mold welding two metal parts together having respective base sections, which includes enclosing the end sections of said metal parts in aligned end-to-end relation in a mold having an entrance gate, flowing molten metal through said entrance gate into said mold, and out of said mold at rates so related as to cause some of the metal admitted into the mold to be discharged from said mold while the rest of the molten metal accumulates as a metal bath to cause the molten metal during the early stage of its admission into the mold to preheat the metal parts, and conducting some of the said molten metal during said early stage from the entrance gate through a recess and directly onto said base sections in direct impingement with said base sections to promote better heat transfer between said molten metal and said metal parts, the improvement comprising discharging molten metal through at least two separate exit gates into separate discharge chambers located