Punching is where there is a die and a punch in the machine and the sheet metal sits between these, like a peice of paper in a hole punch. The machine hits the punch and this forces the punch through the sheet and into the die. Whatever shape the punch and die is will punch that shape into the sheet metal. The bonus of this is if there are a lot of holes it will punch much faster than Lasering them and saves time and money. The downside it we can only punch up to a maximum thickness of 3mm.