Post treatment of investment castings

Heat treatment:In order to improve or change the original organization of investment castings,eliminate internal stress,ensure the casting performance,to prevent the deformation and damage of the castings,heat treatment is required after cleaning investment castings.Heat treatment of investment castings are generally divided into quenching,annealing,normalizing,as-cast conditioning,artificial aging (see aging treatment), eliminate stress,softening and graphitization treatment etc.Such as high manganese steel castings,as it requires high abrasion resistance and enough toughness,the internal organization shall be the austenite.Thus,we need to do quenching processing for investment casting.Namely heating castings into austenitic area to make it completely austenitized.This process is also called water toughening treatment or solid solution treatment.

Plastic:Divided into modification,repair and surface finishing three aspects.Some castings produce deformation during solidification,cooling and heat treatment process, make some sizes out of tolerance, need a correct method to repair.Modification is working at room temperature or temperature condition,which make use of mechanical strength.When the deformation is too large,can also be modificated inside the heating furnace using the weight of investment castings itself or outside added pressure weight.The external defects of investment castings are repaired mainly by use of welding.If the investment casting surface is rough and uneven,we could use hanging wheel or high speed grinding wheel to do polishing finishing.

Rough machining:Before delivery,rough machining should be done for local investment castings according to the technical conditions.After rough machining, we can discover the defects timely and solve asap.Rough machining could also reduce weight of investment castings,also can make the waste and the chip to recycling.

Anti-rust treatment:Normally,investment castings are required to do anti-rust treatment before delivery to prevent ruse during transportation and storage.Usually paint primer or anti-rust oil after final inspection.