All Laser Cutters want two additional devices which move air: blower which removes https://www.ssj-group.com/?s=laser+cutting+air+compressor&post_type=product surroundings / extracts smoke from machine and surroundings compressor as a source for compressed air flow for so called atmosphere assist.
Why and How
Laser cuts by heat, very high heat focused in tight beam. Side products of high heat are smoke and fire, both are not welcomed addition, smoke disperses laser reducint it’s efficienty and fire causes charring of material / edges and can even escape control causing serious emergency.
Fire needs air 
flow to burn but it will also die if you blow too hard, think of a candle in the wind. This is essentialy what air flow assist can be for: compressed surroundings is extruded directly at the laser head in a very limited stream and is fond of the place where laser touches material.
Pressure and volume of air
Pressure of air is essential variable for air assist efficienty, inside our shop we discovered that optimal value is between 2 and 3.5 bar (31-50psi).
To achieve required pressure compressor must push certain volume of air through air assist opening, exact volume depends on size of the starting and desired pressure. Top quality laser beam cutter heads have small and finely tuned openings while cheaper chinese cutters simply blow generally direction via large holes.
Proper compressor
When choosing compressor you have to consider if it can constantly provide desired pressure and volume of air. Small airbrush compressors small compressors boast impressive pressure figures but actually poor flow rates enough only for airbrush pistols. Even if small compressor would be able to push enough air it’ll likely overheat in short while.