- Your First Laser Tube: If you are buying a new laser cutting and engraving machine, make sure you ask for the make, model number and physical dimensions of the tube supplied with the machine. It is not unusual for machine suppliers to exaggerate the laser power output of a laser tube, promising 50 watts and supplying a 40-watt tube (50 watts is the Max power and 40 Watts is the rated power) for example. I have also heard of instances where a machine was sold as a 100-watt system but actually contained a 60-watt laser tube.
- A quick rule of thumb for the narrow tubes (50mm / 2″ diameter) is 5 Watts per 100mm of tube length.
- Fat body tubes (80mm / 3.15″ diameter) are typically 7~8 Watts per 100mm of tube length
- Buying a replacement tube: In this scenario, it is the supplier that you need to consider carefully.
- Correct Laser Power: Check that the specified power actually reflects the tube you are expecting to arrive, it is easy to check the manufacturer’s websites for information on a particular tube.
- Fit a Milliammeter: If your laser machine does not have a milliammeter fitted, it is highly recommended that you fit one yourself. You need to make sure that you do not drive the tube beyond the manufacturers recommended maximum operating current (mA) as this will prematurely age the tube and shorten it’s working life.
- With a Milliammeter fitted you can work out at what percentage power your laser tube operates at its recommended maximum operating current and set this as a limit for all jobs. Many laser software packages will allow you to set this limit within the machine settings.
- Buy a Laser Power Meter: I would suggest you buy yourself a low-cost laser power meter and regularly check the output of your laser tube, it’s also a great tool for troubleshooting problems. For the majority of users, it is not worth purchasing a professional laser power meter at several hundred $ £ € as you are looking for an indicative value rather than a precise value. As laser tubes gradually degrade over time, a laser power meter will help you to decide when the time is right to start getting a replacement.
- Manufactured Date: Each tube will have a date of manufacture printed on the main label. Ideally, this needs to be as close to the current date as possible, but it’s not unusual for this to be up to two months old. This is important as the manufacturer’s warranty starts from the date of manufacture, not the date of delivery.
- Maintenance of the Optical Path: It is important to keep your mirrors clean as well as your lens. On a perfectly aligned and clean optical path, it is not uncommon to lose between 10~12% power, dirty optics will increase this significantly. You should be checking and cleaning your mirrors on a weekly basis, your lens should be checked and cleaned on a daily basis. Running the machine with dirty optics means you will need to either increase the power or decrease the speed to maintain a cut, either way, the laser is working harder or longer than necessary.
- Laser cooling system: If you are able, it is always best to use a fully enclosed cooler or chiller unit which measures both temperature and water flow. This unit should not only give an alarm if there is a problem but stop the laser from operating without sufficient cooling. It only takes a couple of minutes to ruin a tube through overheating. Typically a laser tube should be running at between 15C and 25C, as the temperature rises the efficiency of the tube decreases, resulting in a lower power output.
- However, excessive chilling of the water is not usually recommended as the dew point is typically 5C below the ambient temperature. If you chill the water by more than 5C you run the risk of condensation on the glass. Since one end of the tube could be at 15~20KV there is an increased chance of arcing occurring which can damage sensitive electronics if the grounding circuit is not sufficiently robust.
The original versions of this can be found at How to Get a Longer Life from your Laser Tube