Unfortunately Casenit is no longer available (it had an insignificant amount of cyanide but the EPA went berserk over it!) and most places now sell a product called "Cherry Red" which does OK but does not seem to go as deep as Casenit using the same process. I use a method for "Cherry Red" that will easily get a case .020" or more deep and I have even gotten as much as .050" in just a very short time. If the suggested method of simply heating the part to Cherry red and applying the product then heating again is used a hard case will result but it is usually VERY thin and prone to wear-through. What I do is to pack the parts into a small steel box along with the Cherry Red powder then heat the entire box to red hot, keep it this hot for at least a minute and the case will be about .010" to .015" deep and two minutes will get it about .020" or more deep. This is done almost the same as a carbon pack for case hardening but it works in a fraction of the time!
BTW, do this outdoors if possible because this stuff STINKS when heated!!!!