Unlike dry blasting in which only solid abrasive media is used, wet blasting processes use a slurry in which the media is embedded in water. This greatly cushions the impact energy on the work pieces, providing gentler, yet effective results for delicate work pieces.
As the utilization of wet blasting increases, Rosler reminds manufacturers to review their traditional, dry shot blasting applications and consider if wet blasting could provide additional efficiencies, reduced costs, and better results.
Understanding the Differences
As in any surface finishing process, the starting condition of the work piece, its material composition, shape, and final finish largely dictate which finishing application is most appropriate. Understanding how the application changes the work piece is a key consideration.
In wet blasting, the water cushions the impact of the media, leaving only slight or no deformation on the surface of the work piece. Due to a much higher impact energy, dry blasting with shot can cause substantial deformation of the work piece. Using grit with dry blasting creates an even higher impact energy than shot. The sharp edges of the grit media rip open the surface of the work piece.
Advantages of Wet Blasting
In addition to gentler delivery of media to the work piece, wet blasting technology offers several advantages. Benefits apply to the work piece itself as well as the environment the process is housed within, including:
- No dust – Wet blasting does not generate dust and, therefore, no dust collectors or extra environmental precautions are required.
- No fire/explosion risk – Fire prevention and explosion protection equipment is not required since wet blasting does not present a fire or explosion risk during operation.
- No media impingement – Unlike dry blasting which poses a risk of media particles embedding in the work pieces surface, causing premature corrosion and problems, with coating or painting, impingement does not occur with wet blasting.
- No bending/warping of heat-sensitive pieces – Dry blasting generates a lot of heat which, combined with high impact energy of the media, can cause delicate parts with thin walls to bend and warp. Wet blasting does not.
- Deep surface cleaning – Wet blasting provides deep surface cleaning by removing and immediately washing away any dirt and contaminants adhering to the work pieces.
- Handling limited amounts of grease/oil – While dry blasting requires work pieces to be completely free of grease and oil due to the risk of contaminating the blast media and causing a fire hazard, wet blasting can accommodate oil and grease to a certain degree by injecting a degreasing additive into the slurry.
- Exceptionally fine, uniform finishes – Wet blasting generally produces a lower surface roughness than dry blasting without jeopardizing the overall cleaning effect.
- Cosmetic blasting efficiency – Wet blasting is an ideal way to create a matte, yet very smooth cosmetic finish.
- Holding tight tolerances – The less abrasive nature of wet blasting and lack of warping/bending allows for much tighter tolerances to be held and is especially crucial when finishing delicate pieces with thin walls.
- Adjustable blast intensities and media concentrations – By increasing or decreasing the media concentration in the slurry and the slurry and air pressure, the wet blasting intensity can be easily adjusted.