The Difference between DC Glass and RF Metal Laser Tubes

comparison

Let's Get Started, Shall We?

The world of laser engraving is developing at a rapid rate. Advanced technology continues to change the way laser engraving machines work, providing even more crafting opportunities to start a small business.

Laser engravers have been taking over garages, workshops, and businesses in the United States; engraving wonders such as:

  • Jewelry accessories
  • Glasses and watches
  • Awards and Trophies
  • Signage
  • Business cards
  • Key chains

CO2 laser engraving machines are popular among DIY enthusiasts and business owners for processing the following materials:

  • Wood
  • Leather
  • Ceramics
  • Fabric
  • Glass
  • Acrylic
  • Rubber
  • Marble

The laser tubes typically used in CO2 laser engravers are categorized into DC glass and RF metal tubes. Let’s delve deeper into the differences between these two types of laser tubes so you can choose the best one for your engraving endeavors.

What is a DC Glass Laser Tube?

Invented in the early 1960s, Direct Current glass laser tubes were the first compatible tubes for CO2 lasers. A DC glass laser tube comprises a fragile, long glass container with a laser gas mixture inside. Generally, the laser optics are connected to the glass for sealing the laser mixture and forming the laser resonator. A laser beam is produced when a high voltage DC discharge ionizes the gas inside the container.

A DC laser requires special water cooling equipment for optimal operation. The best way to cool a DC glass tube is to use a water chiller. This chilling device comprises a refrigeration instrument and a pump for water recirculation around the laser to maintain a constant temperature.

What is an RF Metal Laser Tube?

This laser tube features a hermetically sealed metal chamber, which contains the laser gas mixture. Ionized gas (plasma) produces a laser beam through precisely controlled radiofrequency energy.

Originally, Radio Frequency metal lasers were a part of highly demanding military applications. Today, these laser tubes make a popular choice for excellent engraving results.

A Comparison Guide

Both RF Metal and DC Glass tubes offer unique benefits, such as high quality and quick engraving results.

Although metal laser tubes have been the industry standard for many years, they are often expensive and high maintenance. On the other hand, DC Glass tubes are available as a more affordable energy source for engraving or cutting. Let’s take a closer look at how these two tubes measure up:

Cost

RF laser sources are more expensive, having an average cost of 5-8 times more than a DC glass laser source. That’s because of the higher manufacturing cost and technology of an RF laser tube.

For example, an average CO2 40W laser tube costs around $130 to $200, and an RF 40-45W laser source costs around $1,000.

Power Usage Range

An RF laser source can be used between the 2%-99% power range, allowing use on more delicate materials. However, most common material applications will never require those low power settings. 

A CO2 Glass tube is usually used between the 10%-99% power range because settings below 10% can result in laser beam instability. But, most engravers never use those low-power settings anyway.

Quality of Beam 

An RF laser source can produce an unfocused beam diameter of around 2.5 to 3mm. This results in a slightly finer laser beam and a marginal accuracy increase once focused. But, the difference is negligible.

A CO2 Glass laser source will produce an unfocused beam diameter of around  3.5mm-4.5mm. A slightly larger beam diameter has its own set of pros and cons.

For one, a larger beam diameter should be able to cut through thicker materials in fewer passes. Besides, is it really worth spending 5 to 8 times more money for a 1mm difference in beam diameter that will hardly increase accuracy? Diving into the metrics of this case, that’s less than a 0.04-inch difference.  

Overall, RF laser sources are more durable and provide a negligible increase in accuracy. An RF laser source would be most favorable for larger companies who have fast production lines and can afford a larger initial investment. The payoff time would also be less under these circumstances.

Engraving Performance

RF metal laser tubes generate a smaller spot size out of the laser’s output window, resulting in precise and accurate engraving performance. The smaller spot size plays a crucial role in high precision engraving. However, most commercial applications will never take advantage of this unneeded accuracy increase.

Cutting Performance

Both types of laser tubes result in high-quality cutting. However, due to the RF metal laser tube's pulsating lasers, a few materials such as acrylic may show a rough edge. Most people do not notice this difference, but it can be evident if you are engraving an intricate design. This is one area where glass tubes have an accuracy advantage.

Longevity

 

Most RF laser sources can last 5+ years while being used 40 hrs per week (~ 10,000 hrs)

Depending on wattage, CO2 Glass laser sources can last anywhere from 1,200 hours (~ 1-2 years) for a 40W to 10,000 hours for a 150W (~ 5 years).

 

While the extra lifetime seems worthwhile at first glance, the massive cost difference between the two laser tubes shows that CO2 glass lasers are the economical choice. A simple breakdown of price per runtime hour shows that it only costs $0.03 per hour to run a DC glass tube, compared to $0.10 per hour for RF metal tubes. 

You can refill the gases inside the RF, but this process is more expensive than replacing a DC glass laser tube. Over time, maintenance and replacements for a tube can add up. That means investing in a DC glass laser is a wise decision if you don’t have the capital to invest in expensive laser engraving equipment.

Which CO2 Laser Tube Is Better?

The engraving requirements and budget constraints of every small business and user are different. When searching for the best CO2 laser engraver machine, investing in a DC glass laser tube can be a cost-effective solution for your small startup business and engraving endeavors.

Acquiring a water-cooled, DC glass laser tube makes the best option due to its affordable cost and low-maintenance operation. 

How to Get the Most out of your DC Glass Laser Tube

Follow these helpful tips to add more years to your laser’s lifespan and get better engraving performance.

Prevent Overdriving

Don’t forget to check the manufacturer’s recommendations and instructions for optimum current to ensure maximum durability.

Clean Frequently

Cleanliness is a crucial factor in any tube’s life. The dirtiness of one’s lens or mirrors can result in any minor or significant loss of your laser power. You will ultimately have to increase the laser power or lower the operating speed to overcome this loss of power. Also, don’t forget to change your cooling water and clean the water tank regularly!

Prevent Overheating

Never operate a glass CO2 laser tube without using a high-quality chiller. Overheating can cause permanent damage to the laser and reduce its performance. It’s usually best to operate with a water temperature between 60 and 70°F (16 to 21°C).

Find the Best Laser Tubes from OMTech Laser

If you are looking for a professional-grade CO2 laser engraver for your projects or small business needs, don’t forget to check out OMTech and their products and services. They provide top-quality engraving machines, parts, accessories, and more to unlock endless engraving possibilities!