After the matrix material, blasting abrasive and particle size are determined, blasting can be performed. The sandblasting process parameters include air pressure, blast nozzle diameter, spray angle, spray distance, sand blasting time, sandblasting operating environment, and dust extraction. The table shows the effect of abrasive grain size and air pressure on the surface roughness after blasting using alumina abrasive blasting. It can be seen that coarser abrasive particles and higher wind pressure increase the surface roughness; otherwise, it decreases the surface roughness. With the same kind of blasting abrasive and the same air pressure parameters, the surface roughness of the sandblasted surface is high when the hardness and softness of the substrate (such as aluminum and mild steel) are high. Effect of blasting time and air pressure on surface roughness. As the wind pressure increases, the surface roughness increases significantly; while the impact of sandblasting time on the surface roughness shows a sharply increasing linear relationship in the beginning of about 30 minutes, and then the sandblasting time is extended, and the surface roughness is almost nothing. Variety.
The sand blasting angle of the blasting machine is 70 with the horizontal line. A suitable angle of 80~. Sand blasting should not be used. Otherwise, sandblasting efficiency will be reduced due to vertical rebound of the abrasive; however, it should not be less than 45. , otherwise it will affect the sandblasting effect. The sand blasting gun should always maintain a constant blasting angle. Scanning sand blasting the workpiece. Each blasting track should cover about one shot of the previous blasting sand and move continuously from one end of the workpiece to the other. The second pass of sandblasting should be overlapped with the first pass of sandblasting, and this should be repeated alternately until the required surface roughness.
The blasting distance of the sandblasting machine, that is, the distance from the blasting nozzle to the surface of the substrate, depends on the type and granularity of the abrasive, the diameter of the blasting nozzle, and the performance of the blasting machine, and generally fluctuates within a range of 102 mm to 304 mm. Soft sand bodies and thin-walled parts should adopt large sand-blasting distances; while hard-matrix, thick-walled parts, large-size parts and thick coatings should adopt shorter blasting distances. After the sandblasting is completed, dry, oil-free, clean compressed air is used to blow off the floating dust on the surface of the sprayed sand. The fresh surface after sandblasting is forbidden to be contaminated by lotus, and the fingerprints left by finger touches will affect the combination of spray coating. Spraying should be performed as soon as possible after sandblasting so as to prevent the substrate from affecting the coating binding performance due to moisture absorption or oxidation. For steel substrates, the interval time before spraying should not exceed 4 hours and should not exceed 2 hours in wet weather.
The sand blasting angle of the blasting machine is 70 with the horizontal line. A suitable angle of 80~. Sand blasting should not be used. Otherwise, sandblasting efficiency will be reduced due to vertical rebound of the abrasive; however, it should not be less than 45. , otherwise it will affect the sandblasting effect. The sand blasting gun should always maintain a constant blasting angle. Scanning sand blasting the workpiece. Each blasting track should cover about one shot of the previous blasting sand and move continuously from one end of the workpiece to the other. The second pass of sandblasting should be overlapped with the first pass of sandblasting, and this should be repeated alternately until the required surface roughness.
The blasting distance of the sandblasting machine, that is, the distance from the blasting nozzle to the surface of the substrate, depends on the type and granularity of the abrasive, the diameter of the blasting nozzle, and the performance of the blasting machine, and generally fluctuates within a range of 102 mm to 304 mm. Soft sand bodies and thin-walled parts should adopt large sand-blasting distances; while hard-matrix, thick-walled parts, large-size parts and thick coatings should adopt shorter blasting distances. After the sandblasting is completed, dry, oil-free, clean compressed air is used to blow off the floating dust on the surface of the sprayed sand. The fresh surface after sandblasting is forbidden to be contaminated by lotus, and the fingerprints left by finger touches will affect the combination of spray coating. Spraying should be performed as soon as possible after sandblasting so as to prevent the substrate from affecting the coating binding performance due to moisture absorption or oxidation. For steel substrates, the interval time before spraying should not exceed 4 hours and should not exceed 2 hours in wet weather.
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