The term “impregnation depth” refers to the thickness of the diamond impregnated matrix layer on a core bit crown as shown in the illustrations below.
This bit crown profile is offered in standard impregnation depths of 6 mm (0.24 inch), 9 mm (0.35 inch), 12 mm (0.47 inch), and 16 mm (0.63 inch).
Note that impregnation depths greater than 9 mm (0.35 inch) are not available for thin-wall core bits with kerf widths of less than 0.33 inch (8.4 mm).