How Do Hardness And Particle Shape Affect The Performance Of Waterjet Cutting

Virtually every abrasive known to man — both natural and synthetic — has been considered for use in waterjet cutting. 

SEPPE almandine garnet has emerged as the mineral with the best characteristics for abrasive waterjet cutting. Other minerals may be harder, but SEPPE almandine garnet is the abrasive with the best combination of characteristics for waterjet cutting. The naturally occurring material is mined and processed for numerous industrial applications in addition to waterjet cutting, such as sandblasting media and water filtration applications. 

The common almandine garnet is brownish-red in color and opaque. The much rarer, gemstone-quality almandine garnet is marked by a deep red color and is transparent. The alluvial river garnet seems to pink.

Other abrasives can be used in waterjet cutting. Aluminum oxide is harder than garnet and is sometimes used for cutting very hard materials such as ceramic. One drawback, however, is that using aluminum oxide dramatically shortens mixing tube life, increasing the cost of the operation. Staurolite is a naturally occurring mineral with a density and hardness similar to garnet and is an economical general-purpose waterjet abrasive.