I recently bought a Snap On air hammer and I actually browsed thru the book. I found this statement re warranty in the back and it sounds perfectly reasonable to me. Anyway, here is their warranty statement, in writing:
"Consumable products are not covered by any warranty. Consumable products are goods reasonably expected to be used up or damaged during use including but not limited to drill bits, saw blades, grinding discs, sanding discs, knife blades, files, taps, dies, oxygen sensors, and batteries"
Now, I'm sure many people will get the above replaced on warranty despite what is says. But if you are denied, that covers it.