All Laser Cutters want two additional devices which move air flow: blower which Air Compressor For Tire Production Equipment removes surroundings / extracts smoke from machine and atmosphere compressor as a source for compressed atmosphere for so called atmosphere assist.
Why and How
Laser cuts by heat, very high temperature focused in tight beam. Side items of high temperature are smoke and fire, both are not welcomed addition, 
smoke disperses laser reducint it’s efficienty and fire causes charring of materials / edges and can even escape control leading to serious emergency.
Fire needs surroundings to burn nonetheless it will also die in the event that you blow too hard, think of a candle in the wind. That is essentialy what air assist can be for: compressed surroundings is extruded directly at the laser head in a very tight stream and is fond of where laser touches material.
Pressure and level of air
Pressure of atmosphere is key variable for air aid efficienty, inside our shop we found out that optimal value is between 2 and 3.5 bar (31-50psi).
To achieve required pressure compressor needs to push certain volume of air through air flow assist opening, exact volume depends on size of the starting and desired pressure. High quality laser beam cutter heads have little and finely tuned openings while cheaper chinese cutters just blow in general direction via huge holes.
Proper compressor
When choosing compressor you should consider if it will be able to constantly provide desired pressure and volume of air. Little airbrush compressors little compressors boast impressive pressure figures but really poor flow rates enough limited to airbrush pistols. Also if small compressor would be able to push enough air it will likely overheat in couple of minutes.