1. General requirements
Gases used for drying, sandblasting or other processes should be dehydrated and deoiled.
Wear dry and clean gloves during and after sandblasting.
2. Sandblasting material
Use silica (SiO2), aluminum oxide (Al2O3) or other sand materials approved by both sides of the supply and demand as sand blasting materials.
The purity of silica (SiO2) and aluminum oxide (Al2O3) sand should be greater than or equal to 95%, including ferrous oxide (FeO) content should be less than or equal to 0.3%, Mohs hardness ≥7. According to the surface roughness of the casting, the sand particle size is determined, the fine particle is 40μm~50μm, the coarse particle is 150μm~400μm. Other particle sizes can be selected on the condition that the surface quality is guaranteed.
The sand material used for sand blasting should avoid oil pollution. Sand sprayed with other metals cannot be used to treat
titanium alloy materials to avoid contamination.
3. Sandblasting parameters
The pressure of compressed air or water flow for sandblasting should be 0.1mpa ~ 1.0mpa. According to the structure and size of the casting, the distance from the nozzle to the surface of the casting should be kept at 20mm~400mm, and the injection Angle should be controlled at 20°~70°. Other distances and angles can be selected on the condition that the injection quality and operation safety are satisfied.
Sand blasting operation
Before casting sandblasting, foreign bodies on the surface should be cleaned first, and then sandblasting. After penetration inspection or processing of castings, should be first alkaline washing or pickling treatment, and then sandblasting.
After cleaning the casting, sand blasting should be carried out within 12h. Determine the duration of sandblasting according to actual needs to achieve uniform surface roughness.
When casting sandblasting, dry sandblasting operation should be operated in a special sandblasting room or space. Water sand blasting should be rice with special liquid sand blasting device.
When sandblasting, castings should be placed on a fixed sandblasting table, fixed by labor loading or casting weight, and most of the castings should be guaranteed to be in the range of sandblasting. For small castings that cannot be fixed by manual assembly, special gloves are allowed to be worn when sandblasting water.
The sandblasting process should be designed according to the casting structure, and the sandblasting operation should be completed according to a certain route, and local area over or under spraying should be avoided.
Castings with a certain thickness are suitable for sandblasting. For castings with thin thickness (≤2mm) or poor stiffness, sandblasting can be supported by supporting tools consistent with the single-sided shape of the casting.
When casting part sandblasting, other areas should be protected.
After sandblasting, clean with clean water or non-halogen solvent, and then clean with compressed air.
5 sandblasting quality
The castings after sandblasting should meet the following requirements:
The surface roughness should reach Ra3.2μm~Ra12.5μm.
The surface roughness shall be uniform and free of oxide scale, sandblasting debris, discoloration, grease materials, fingerprints and other contaminants.
If the above situation occurs, should be re-sandblasting treatment.
The casting deformation should be corrected after sand blasting treatment.
The abrasive used for sandblasting should be checked regularly and meet the requirements of 2. If not, the sandblasting material should be replaced.
