> Spanking is a form of corporal punishment involving the act of striking, with either the palm of the hand or an implement, the buttocks of a person to cause physical pain

Straight from wikipedia.

There is no punishment mechanism to spanking without pain. This sort of strange homeopathic idea of spanking is unrealistic and I'm unsure why you're trying to paint this false picture of the world - the vast majority of parents who spank do so with the intention of causing pain to discourage behaviour.