How many times does a tattoo needle penetrate the skin per second?

Between 50 and 3000 times per minute, so between one and fifty. Modern guns have adjustable speeds, which an artist changes according to skin type and area. Since fleshier parts of the body require more ink, the needle is often sped up, and on the other hand, skin in older people is much more delicate, so the speed is slowed down to avoid any possible tearing. 

160 per min but it depends on how good the person is 

Perform surgeries is the correct answer.

Wash your hands often and recycle your trash instead of just throwing it away.