How many kinds of different abrasives used for shot blasting machine?

Sand is the most common abrasive used for shot blasting, and therefore the process is generally referred to as sandblasting. The other abrasives used for shot blasting are garnet, chilled iron, olivine and glass beads. The first two are extremely coarse and abrasive and they are not to be used on soft surfaces. However, olivine and glass beads are generally used as polishing agents and they can be used on delicate surfaces like metals, plastic, rubber and glass.