The nut of a black walnut has a much stronger flavor than an English walnut. That strong flavor makes it a desirable nut for baking, in ice cream or used as a topping. The shell of black walnut is one of the most difficult shells to crack and takes slowly applied pressure against the seam to get larger "nut meat" pieces. There are commercial "nut crackers" available but a slowly tightened vice seem to be effective.
The ground up shells provide special products. Manufacturers use shells to deburr precision gears. Ground shell products are also used to clean jet engines, as additives to drilling mud for oil drilling operations, as filler in dynamite, as a nonslip agent in automobile tires, as an air-pressured propellant to strip paints, as a filter agent for scrubbers in smokestacks, and as a flour-like carrying agent in various insecticides.