All Laser Cutters need two additional products which move air: blower which removes air flow / extracts smoke from machine and air flow https://www.ever-power.net/?s=laser+cutting+air+compressor&post_type=product compressor as a source for compressed atmosphere for so called surroundings assist.
Why and How
Laser cuts by temperature, very high heat focused in tight beam. Side items of high temperature are smoke and fire, both are not welcomed addition, smoke disperses laser beam reducint it’s efficienty and fire causes charring of materials / edges and can even escape control leading to serious emergency.
Fire needs air flow to burn nonetheless it can also die if you blow too hard, think about a candle in the wind. This is essentialy what air assist can be for: compressed surroundings is extruded 
straight at the laser head in a very tight stream and is directed at the place where laser touches material.
Pressure and volume of air
Pressure of air is key variable for air support efficienty, in our shop we found out that optimal value is between 2 and 3.5 bar (31-50psi).
To attain required pressure compressor needs to push certain level of air through surroundings assist opening, specific volume depends upon size of the opening and desired pressure. High quality laser beam cutter heads have little and finely tuned openings while cheaper chinese cutters simply blow in general direction via large holes.
Proper compressor
When choosing compressor you have to 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 actually poor flow rates enough only for airbrush pistols. Also if small compressor would be able to push enough air it’ll likely overheat in short while.