In barrel finishing or tumbling, workpieces, abrasive particles, and a fluid are tumbled in a slowly rotating container. In vibratory grinding, also known by the trade name “trowalizing”, the container vibrates. The fluid can be water, acid, or alkaline compound [MENA00]. Barrel finishing and vibratory grinding are applied in die and mold manufacturing, medical and aerospace engineering for deburring, degreasing, polishing, or derusting [BROC11].
The abrasive particles, also called “chips”, can be ceramic, plastic or metallic materials and have various shapes (Fig. 4.10). Sizes range from edge lengths of 3-25 mm or more. Vitrified bond is the dominant bond type for chips with abrasive action [KLOC09, p. 57]. Steel particles are used for ball burnishing, i. e. inducing compressive stresses. Coarse chips are sized through sieving according to ANSI B74.11 [ANSI03].
The liquid carrier compound ranges from acidic to basic pH values and has additional tasks such as removing contaminants from the process, keeping the machined parts clean, etc. The compound type is chosen under environmental and economic considerations.
In abrasive blasting, the abrasive grits are energized with compressed air, centrifugal force, or pressurized water and aimed at the workpiece material. Corundum, silicon carbide and quartz are typical abrasive grits for blasting [KLOC09, p. 371]. Emitted particles [particulate matter (PM)] and particulate hazardous air pollutants (HAP) are the major concerns relative to abrasive blasting [EPA97]. Several methods exist to control the air emissions, such as blast enclosures, vacuum blasters, drapes, water curtains, wet blasting, and reclaim systems [EPA97].