Precision casting production tray, basket, stents and other heat treatment equipment, can appear sometimes casting defects such as surface crack, some tiny crack can repair by welding repair defects:Cold welding machineCommon disadvantage is that efficiency of welding repair welding and argon arc welding machine is better than high, but in the repair of millimeter defects and machined surface defect, its prominent advantages make people prefer to choose cold welding.All kinds of cast iron production is about 8 million tons per year in China, there are all kinds of casting defects accounted for about 10% ~ 15% of the annual production of cast iron castings, known as the rejection rate is 10% ~ 15%, if the casting scrap, iron by 1997 average price calculation, the loss every year is as high as 1 billion yuan of above.The welding method to repair the defective castings, due to the welding of low cost, not only can obtain enormous economic benefits, but also to complete production tasks in a timely manner.