The guillotine was not a torture device, it was a method of execution.
There was no torture under the Revolution. Torture had been partially abolished in 1781 by Louis XVI, then completely in 1788-1791. Drowning, guillotine, firing squad all fall under death penalty, and thus can be seen as "inhuman and degrading punishment" but not torture, as torture is (roughly) physical maltreatment in order to get intelligence.
It wasn't used during the Revolution, as justice was expeditive.
Good article here: en.wikipedia.org