The defect distribution of sand castings after processing is shown in Figure 1, figure 2 and figure 3. The sand inclusion on the processing surface has not been improved, and there are more sand inclusion in dispersion type. The sand inclusion defect of motor shell produced by alkaline phenolic resin sand is similar to that of furan resin. The sand inclusion defects are basically on the inner surface. There are about 5 sand inclusion defects on the end face, and the parts are not fixed. The sand castings with sand inclusion defects are 100%.
No air holes are found on the inner surface of sand castings. Air holes generally appear on the end face, with an average of about 2. The position is not fixed. The sand castings with air holes account for about 10% of the total sand castings. The number of cracks found after magnetic particle flaw detection on the inner circular machined surface is small. Occasionally, 1-2 sand castings with a length of about 5mm appear on the inner surface, and there are flaw detection cracks at the root of the end face riser. The sand castings with crack defects account for about 10% of the total number of sand castings, while more than 10 micro crack defects are found in each piece of furan resin sand process machined surface flaw detection.
