Fitter in the scraping of cast iron plate (cast iron platform) operation, the platform scraper against the hip bone, both hands holding the tool so that the plane scraper and cast iron plate (cast iron platform) was scratched the surface to form a certain degree of cutting and the blade pressure Flat blade blade tight plane. At this time, the waist of the hip of Han Chinese thrusts the handle to cut the blade into the flat metal surface of the cast iron and cut the blade into the ground black spot in the depth direction. Then the pressure of both hands is immediately turned to elevate the blade (cast iron platform) Quickly lift away from the cast iron plate surface. Completed the excavation of the cutting tool forming cutting process, and scraping a layer of very thin metal, tool operation has three methods, namely straight push method, straight push plus twist method, left and right twist method. Direct push method produces rectangular blocks and triangular blocks. The surface is in the form of microwave. The quality of the surface is poor. It is suitable for rough scraping: the direct push plus reverse method produces anti-6 blocks, positive 6 blocks, the surface is of positive microwave type, Smooth and suitable for fine scraping. Left and right twist method produces scales, inverse scales, Yan Wing block, Yan body block, the surface was fine curve waveform, surface quality bright and smooth, suitable for fine scraping. From the scraping process, scraping is the full role of the process, operating proficiency determines the pros and cons of scraping quality. Black spot rate. R & D cast iron plate (cast iron platform) After grinding, the raised part of the surface of the cast iron plate shows all black spots, black spots, dark spots, dark spots. These points are a variable in the study. After a continuous cycle of continuous continuous operation of scraping research, the black word from thick to dense, from uneven cloth into uniform distribution, the black point of the gradual process, but also the surface finish, surface angle accuracy, the surface geometry increased by the process of. ?