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Thursday, 11 September 2014

Inspection of Castings

Inspection of Castings Points : Inspection of Castings Process, Inspection of Metal Castings In arrange to conclude the existence of every defects (not readily visible) it becomes required to inspect the casting. Following methods are working to check the casting. 1. Destructive Inspection Method Destructive inspection method the casting example is cracked during check. This method is use to test mechanical properties, such as, tensile strength, hardness etc. These tests are execute on the test bars or pieces cut as of casting sample. 2. Non-Destructive Inspection Method The various methods are of nondestructive inspection: a. Visual inspection The major plan of this type of inspection is to make sure that outward form of casting looks good. Through this inspection defects like cracks, tears, run outs, swells etc. might be detected. b. Dimensional Inspection Dimensional inspection can be carried out through surface plates, height and depth gauges and plug gauges and so on. Through this inspection it can ascertain whether definite details are inside tolerances or not. c. Pressure Testing Pressure testing is working to place leaks in a casting or to check generally strength of a casting in resistance to satisfied under hydraulic pressure. It is carried out on tubes and pipes. d. Radiographic Inspection Radiographic inspection is working to inspect internal defects of a casting, with use of X-ray or gamma ray method. e. Magnetic Particle Inspection Magnetic particle inspection is working on magnetic ferrous castings for detecting invisible surface or faintly subsurface defects. f. Fluorescent Penetrant • This kind of inspection is working to find minute pores and cracks on surface of castings that can be missed even in magnification.

• In this process a fluorescent penetrating oil mix by whiting powder is apply to casting surface by spraying, dipping, or brushing. Cracks or other defects become visible after surface has been wipe dry (the oil creeping out of cracks).
g. Eddy Current Inspection Eddy current inspection materials of casting require not be ferromagnetic. Test includes a probe which is supplied by a high frequency current. It induce an electric field in casting. Field changes in presence of surface or near surface defects. These changes show up on instruments.

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