close up of laser cutter
22 Dec-2020

5 Answers That Show the Differences Between Glass and Metal CO2 Laser Tubes

Buying a CO2 laser machine is a major investment. As such, you need to ensure that the one-time cost won’t turn into a host of unplanned maintenance and repair expenses down the line. One of the potential sources of these unexpected challenges is tube type. Not all machines are created the same, and that’s why you need to determine if your particular unit has glass or metal CO2 laser tubes. This distinction could mean the difference between an okay and a great experience.

Understanding Power Ratings

There’s a general guideline that applies to all tube types, and it has to do with the unit’s size. For example, some suppliers may say that a 1000mm tube is capable of 60W. But tubes with dimensions of 55 x 1000 mm have a maximum power output of 50W, while a tube that measures 80 x 1400 mm is usually 100W. When you see the maximum ratings for any laser machine you intend to buy, compare them to the guideline and make sure the numbers you’re seeing match up.

Glass CO2 Laser Tubes

Glass CO2 laser tubes rely on direct current, DC, to excite the carbon dioxide gas. Machines with DC tubes are mostly used for nonmetal materials, such as acrylic, wood, leather, plastic, paper or bamboo. The beam diameter, also called the laser spot size, tends to be larger with glass tubes. However, glass beams still produce good work, especially when it comes to engraving. Because it does rely on DC, the pulsing action is not that fast, so engraving speeds tend to be lower. However, with a glass tube that has been thoroughly tested like from Thunder Laser, you are able to achieve much faster engraving speeds because of the higher quality glass tube. All glass tubes are handmade, so being able to choose the “cream of the crop” is very important from a performance perspective.

Metal Laser Tubes

Metallic laser tubes use radio frequency, RF, alternating current to excite the gas, making them better at pulsing. Along with their smaller spot size, these laser beams create engravings with fine detailing.

Every budget is different, and understanding which laser cutting tube is better depends on the project. There are a few fundamental questions you need answers to before deciding which to use.

What Are the Cooling Differences?

Because RF tubes are used for high-pulse jobs with quick repeatability, they get hot quickly and use an air cooling system. Glass tubes, however, are not so simple. Glass doesn’t conduct thermal energy as well and requires a water-cooling system. Water needs to be constantly flowing through the system to keep the tube cool, or it will overheat and get damaged. Of course, due to the constant DC, this cooling mechanism creates a potential hazard that requires vigilant care.

Which Is More Precise?

Whether you’re etching or engraving, precision is paramount. Precision and pulse rate are directly related. The higher the pulse rate, the more precise the beam. To get a higher pulse rate, the laser gathers the heat and then rapidly releases it, meaning it’s not heated continuously. When it comes to direct current, there is no room for that rapid gather-release process, because direct current is continuous. This means pulses from glass tubes are less frequent. Therefore, a glass CO2 laser engraver is more limited in pulse rate and tends to execute lower-quality engravings than its metal counterpart.

How Do They Cut?

When it comes to cutting, the material usually dictates the power settings. If you’re working with materials such as plastic or paper, then the minimum you need is about 30W at about 20% for engraving. Some may favor glass tubes because they work well in lower power settings. Metal laser beams do create more refined work, but they tend to leave slightly rougher edges that are imperceptible to customers and can be smoothed easily.

Which Lasts Longer?

By its nature, glass is more fragile than metal. But in the case of a CO2 laser cutting machine, it’s more so. The process of keeping the heated CO2 glass laser tube cool introduces a significant point of failure because it doesn’t handle heat well. Another issue is that the optics and electrodes are constantly bombarded with ions, which increase its rate of deterioration. This is why many warranties only cover six months after purchase. By contrast, metal CO2 laser tubes tend to last anywhere from three to six years with proper maintenance.

Which Is Cheaper?

When it comes to buying a CO2 laser machine for your business, glass tubes tend to be cheaper than metal tubes. However, the metal tubes last longer. But which is actually cheaper? Epilog and many other RF lasers claim to last 10,000 working hours or more. This is fairly accurate and equates to running the laser 40 hours per week for five years. There are also glass tube manufacturers that claim 8,000 – 10,000 hours but this is not very accurate. Most glass tubes will last in the 2,000 – 4,500 hours range which is 1-3 years of use at 40 hours per week. However, considering the cost to recharge or replace a metal tube is often 3x – 5x higher, there are no real cost savings with a metal tube vs glass. An RF tube is usually not needed for most users, unless they require very high precision engraving. Simple logos, monograms, letters, etc will not be any different with glass vs metal tubes. Even photo engravings can be quite good with a glass tube, especially if you add our hi-resolution laser head.

One Note About Cleaning Your Tubes

Executing regular maintenance of your laser cutter goes a long way to extending the usable lifespan of your tubes, whether they are glass or metal. The one caveat many manufacturers will mention is to be careful when using hydrochloric acid with glass tubes because it could damage the glass. If your DC tube is really soiled with sediment, carefully flush it repeatedly with a diluted 3% or 5% HCL solution until it’s clean. Remember to also flush the cooling system, which will reduce sediment and residue deposits.

Laser systems are crucial to many businesses large and small. Whether choosing to work with glass or metal CO2 laser tubes, Thunder Laser USA stands ready to help you find the system that works for you. Call us at 903-522-4070 to speak to one of our professionals, or email us at [email protected].