FAQ

CO2 Laser Engravers and Cutters

One of the first decisions when buying a CO2 laser for cutting and/or engraving is the option between a Direct Current or Radio Frequency excited laser tube. To understand the differences in each laser, we must first understand how each laser works.

Water Cooled Glass Tubes:

Direct current (DC) lasers are most commonly made of glass.  Inside this glass tube is a mixture of gases, carbon dioxide, helium, nitrogen, hydrogen and xenon.  Electrical energy is sent through the tube.  This energy excites the gases resulting in a direct electrical discharge.   The discharge creates a photonic laser beam that bounces back and forth until a certain level of energy is attained, then the photonic (light) beam exits the laser at one end.  This infrared beam is invisible but powerful and once focused can be used to cut or engrave various materials. By the way the word LASER is actually an acronym that describes this process:  Light Amplification by Stimulated Emission of Radiation.

RF Metal or Ceramic Tubes:

An alternative way to transfer energy into the gas is via. radio frequency (RF). RF tube technology is commonly referred to as “metal” tubes. RF excitation produces a pulsed laser with an extremely quick repeatability. Unlike the parallel discharge in a DC excited tube, the RF laser discharges perpendicular to the resonator.

Comparison:

When deciding which laser is best suited for your application, understanding the pros and cons of each laser is critical. Below we break down the major factors when considering these different technologies.

Cost:

DC lasers made of glass (High Quality 8 to 10,000 hrs maximum life) are roughly 25% of the price of (High Quality up to 40,000 hrs life) RF lasers. The DC laser cost advantage is a result of a lower technology, maxmum life and manufacturing costs.

Cutting Performance:

Both types of lasers maintain high quality cuts, the edge quality is very similar. However, because RF lasers are pulsed, some materials may show a slightly rough edge. With that being said, this difference in quality is hardly noticeable to most users. RF lasers with a much smaller spot size will allow you to achieve a much higher precision on smaller items.

Engraving Performance:

RF lasers generate a much small spot size, this allows for very high precision bitmap engraving, For bitmap photo engraving the speed that the RF laser can react to changes in pixel colour (very fast) compared to a glass tube (very slow). This means that a glass tube can't compare in the quality of output or speed (Typically 2.5 times faster) with RF lasers. This problem gets worse at higher power in glass tubes. Making glass tubes over about 70 watt totally unsuitable for engraving.

Longevity:

If you have a glass tube you can only drive it at about 80% of its rated power without decreasing its life considerably. Not only is the maximum power you run a glass tube at, the water cooling temprature must be controled with accuracy to get the rated life. RF lasers being air cooled are regulated internaly giving a 24 hrs duty cycle at full power with no decrease in life. RF lasers last 4-5 times longer than (High quality) DC lasers. This longevity can help offset the initial higher cost of the RF laser. The gases inside RF lasers can normally be refilled. This process can be more expensive than the replacement cost of new High quality) DC laser. But you can expect the RF tube to have at leased another 20,000 hours use afer servicing.

Comparing Laser Output:

If you were to compare a 100W RF to a 100W DC tube and assuming all things are equal, the power is the same. Although the RF can use its full rated power. The RF power focuses that same energy into a more dense, smaller spot size. The quality and stability of that beam is much better as well. For engraving, detailed etching and smaller cut quality, the RF can offer significant advantages. However, for cutting you can initially afford to ‘buy’ much more cutting power compared to the cost of RF. So, determining what you will be using your laser for will help you make that decision.

Fiber Lasers

Pulsed Fiber Lasers are renowned for their versatility with laser marking being one of the most popular applications. Although similar to laser engraving, the appliance of a mark is at a surface level, whereas engraving is a mark with depth. Laser marking is the process where a material, which can be anything from ceramics, plastics, metals, LEDs, rubber, graphic composites, etc. is marked or labelled with a simple black mark, or in colour (depending upon the material).

One of the biggest benefits that a fiber laser offers to its users is that it is extremely stable.

The process leaves extremely precise, accurate and high-quality marks that are easily readable by the human eye and by machines too. The mark is durable and can be easily traced; this is an important quality to have when many parts that are laser marked need to be traced back to their original source.

It is also able to work with extremely small measurements, leaving tiny, yet still high-quality, marks. The beams used in this type of process are extremely powerful, reliable and controllable, delivering the quality previously mentioned.

Other normal lasers are very sensitive to movement, and should they get knocked or banged, the whole laser alignment will be thrown off. If the optics themselves get misaligned, then it can require a specialist to get it working again. A fiber laser, on the other hand, generates its laser beam on the inside of the fiber, meaning that sensitive optics aren’t required to have it working properly.

Another huge benefit in the way that a fiber laser works is that the beam quality that is delivered is extremely high. Because the beam, as we’ve explained, remains contained within the core of the fiber, it keeps a straight beam that can be ultra-focused. The dot of the fiber laser beam can be made incredibly small

Many other lasers will typically only convert a small amount of the power that it receives into a laser. A fiber laser, on the other hand, converts somewhere between 70%-80% of the power, which has two benefits.

The fiber laser will remain efficient by using near-to 100% the input that it receives, but it also means that less of this power is being converted into heat energy. Any heat energy that is present is evenly distributed along the length of the fiber, which is usually quite long. By having this even distribution, no part of the fiber gets too hot to the point where it causes damage or breaks.

Pulsed Fiber Lasers are renowned for their versatility with laser marking being one of the most popular applications. Although similar to laser engraving, the appliance of a mark is at a surface level, whereas engraving is a mark with depth. Laser marking is the process where a material, which can be anything from ceramics, plastics, metals, LEDs, rubber, graphic composites, etc. is marked or labelled with a simple black mark, or in colour (depending upon the material).

Finally, you’ll also find that a fiber laser works with low amplitude noise, is also extremely resistant to heavy environments, and has low maintenance costs. Generally, an SPI fiber laser will require no servicing as they are built with our ‘fit and forget’ technology. However, for the rare occurrence maintenance should ever be required costs are typically around 50% less than other lasers.

As the name suggests “laser colour marking” is the use of a laser to add a mark, to brass, titanium or stainless steel which thermally alters the surface to give the appearance of a variety of colours to an object. This has particular relevance in the jewellery industry for the marking of jewellery items with colour for increased aesthetic appeal.

The fiber laser beam is directed at the piece of jewellery in the area where the mark is required. The thermal heat from the laser beam alters the surface structure of the material, forming a permanent coloured mark to the exact shape required, as per the fiber laser programmed instructions.

By applying variations in the pulse width, the laser operator can control the amount of heat, which is being applied to the surface of the jewellery piece. By applying small changes to the pulse width and pulse frequency the oxide layer thickness can be varied. This creates discreet changes in the colour of the mark to the eye of the viewer.

It is unique as a process in that it doesn’t take away any of the material that it is working with, unlike other processes such as laser engraving. Instead, it heats up the area that it is targeting, causing oxidisation. This, in turn, causes a colour change beneath the surface of the material, leaving a permanent mark.

Laser marking is an environmentally friendly process. This is because it doesn’t use things such as chemicals or inks found in many of the more traditional marking methods. Lasers, particularly fiber lasers, also use much less electrical energy than these other types of marking processes.

As well as being apt at working with a range of materials, laser marking is also perfect at operating with a range of object shapes and sizes too. This may be large and simple objects, or it could be small and complex ones.

A wide variety of materials can be colour marked. These include:

  • Metals – brass, steels, titanium
  • Ceramics and plastics – although less applicable to the jewellery industry, colour marking can also be applied to ceramics and plastics too