How to protect the non-sprayed parts before spraying

       For the non-sprayed parts of the workpiece substrate adjacent to the sprayed or sandblasted parts, in order to prevent the melt jet or sandblasting abrasives from splashing on the parts, shielding protection should be carried out. Depending on the shape and location of the parts, the following shielding protection methods are commonly used.

      1) Masking tape or pressure sensitive tape for protection

      This tape can withstand the high temperature of sprayed droplets, does not burn, does not flow, and does not contaminate the workpiece. This tape is suitable for the protection of parts with complex shapes and the masking of local parts that are difficult to make fixtures. And the protection part and the spray part are on the same surface. When the sprayed layer is thick, the coating deposited on the protective tape should be cleaned frequently during the spraying process to prevent the sprayed layer from accumulating on the tape and avoid difficulty in tape removal and damage to the edges of the coating.

       2) Paint protection

       This is a water-soluble, heat-resistant inorganic coating that is applied to the area to be shielded after the parts are sandblasted. During the spraying process, it is affected by the jet flame to form a complete heat-resistant protective film, which resists the erosion of the jet flame, protects the substrate of the sprayed part, and has no corrosive effect on the substrate. This kind of paint protection is suitable for the protection of the parts adjacent to the sprayed part but not at the same level as the sprayed surface. If it is used for protection on the same plane, especially when spraying a thick coating, it will be difficult to separate from the spray coating at the spraying site due to the accumulation of a "coating shell" on the protective coating film.

       3) Metal plate or fixture protection

       Use thin steel plate, copper plate or aluminum plate to make protective cover plate, or make protective cover or clamp according to the shape of parts for shielding and protection. This type of masking material can be used repeatedly, and is suitable for masking and protecting the non-coated parts of mass-produced sprayed parts. However, it is not suitable to use low melting point metals or very soft metals, such as Sn, Pb and other materials.

       4) Shielding protection of pin holes and oil holes

       Graphite, chalk, refractory clay, metal plugs, etc. can be used for packing protection, but they should be easily removed.

       5) Protection of organic elastomers and wood

       Rubber, organic elastomer or wood can be used to mask and protect non-blasted areas during processing.