Wind power castings have a large wall thickness, a long time for molten iron to solidify, and a large amount of gas from the sand mold. The castings are prone to sand sticking defects. Therefore, the choice of the quartz sand particle size for modeling is very important. Sand for wind power casting moulding, with a grain size of 40-60 mesh.
The compactness of the sand molds of wind power castings is very important to resist the expansion of the castings, give full play to the feeding effect of graphitization expansion, and eliminate the shrinkage defects of the castings. The resin sand molding equipment should be large enough. For example, choose a large-scale lifting continuous sand mixer with a sand mixing volume of 150t/h. The sand mixing range is 6~12m, equipped with a large vibrating table and a motorized roller table, and the sand box filling time is controlled within 12 minutes, before the head sand hardens The vibration of the shaker can increase the compactness of the sand mold.
In recent years, suppliers have introduced special shielding coatings for ductile iron, which can isolate the contact of harmful gases in the sand mold with the castings, adsorb sulfur and other harmful elements, and prevent the surface layer of the castings from spheroidizing recession or graphite distortion. For wind power castings, all cast iron coatings are not conducive to surface quality. Generally need to use high-refractory paint and cast iron paint in combination. The first layer is made with alcohol-based zircon powder paint, and one more layer is applied to the area that is easy to stick to sand, and then two layers of cast iron paint or special paint for ductile iron are applied. The quality of the last layer of paint is very important. The paint is diluted to reduce the brush marks and improve the surface quality of the casting.