Water vs. Air, can you explain the Pros & Cons?
Laser tubes generate a tremendous amount of heat and the higher the wattage the more heat generated. Laser tube manufacturers in the small cabinet category ALL require the laser system manufacturer to devise a cooling method for the laser tube to prevent damage to the laser tube. The two methods available are water cooled and air cooled.
All CheckMate laser systems are water cooled. Water cooled is far superior to air cooled as the air cooling method can only be as cool as the surrounding/ambient air. Also air cooled laser systems require a number of “fans” to “pull” the laser generated heat away from the laser tube, the higher the wattage the more fans required to pull this hot air away from the laser tube, making for an extremely loud fan system. Water cooled ensures the laser tube maintains a consistent steady temperature and is much quieter as fans are not as essential to the safe operation of the laser system.
A quick laser tutorial:
Laser tubes operate by pulsing/throbbing the “light” energy, it is never a consistent stream of “light”, such as what you would see an LED red diode laser pointer a seminar speaker would use, but instead a pulse or throbbing output of energy.
When laser engraving an image the pulse is never consistently on as the image being laser engraved determines how often the beam needs to fire. Hence the laser beam is not required to pulse constantly on a raster engraved image. Where you will see a close to constant firing is in a large engraved area, such as a large white square, most, not all, but many laser tubes will create an image that has banding, this looks like horizontal bars across the wide white area (darker than the surrounding area), usually in 1/4″ to 2″ in size, in evenly spaced distances from each other, makes for an unacceptable, unsaleable product. This phenomenon is created by various conditions, such as, laser tube, heat buildup, power output, motion system, size of the white area, etc. but primarily caused by the laser tube’s method of energy output, i.e., pulsing.
Even more important is when cutting with a laser system, this is because now the laser beam must attempt to simulate an LED red diode laser pointer by attempting to pulse as many times as possible to simulate the “always on” firing method. This is called PPI (Pulses Per Inch), so the tube still only pulses, but when cutting materials you want the pulsing to be as often as possible simulating “always on”, this allows for quick and clean cutting, leaving a clean smooth edge without a lot of residue from burning the material instead of cutting it.
Now when cutting, the cooling method is even more essential because the laser tube is working overtime, it basically is working at its hardest when cutting as the beam nearly never turns off, unlike engraving where the tube only fires when there is a dot to be created, so it is on/off many times. Cutting is where you see the greatest benefit to water cooling, especially when the temperature gets excessive say 80+ degrees. Then you begin to see anomalies in the laser engraved image because the laser tube is overheating and that affects the laser beam output, hence banding, quality, etc.
Why does the industry no longer use water cooling?
The simple, short answer; COST & competitive pressure!
Long winded answer; Back in the early days of the laser industry many laser systems in the 50 watt or higher wattage range utilized water chillers. Due to the $3500-$5000+ cost (for water chillers) adding to the overall (already expensive) cost of the laser systems and the fact that customers continually wanted the best price possible each laser manufacturer began phasing out water chilled systems, hence competitive pressures forced allthe laser manufacturers to move away from Water Cooling to Air Cooling. Bad decision for the customer. To prove the point high wattage systems in the 150w range and higher wattage laser systems ALL utilize water chillers, some chillers as large as a typical living room. Without this cooling method these systems could not operate properly, produce poor cutting quality and laser tubes would burn out, causing millions of dollars in lost revenue and repair costs. So why do manufacturers not at least offer a water cooled option for their lasers? A question to contemplate…
Is piped water required to operate a water cooled laser?
Not at all, the water pump, water circulator and water chiller all are self-circulating water systems, no piped in water required. All that is required is clean distilled water, other water(s) tend to have minerals and such that could eventually degrade the metallic components of the water system.