Comparison: Galvo lasers versus flatbed lasers

As we know, there are many wavelength lasers that can be used for marking / engraving. The predominant ones are CO2 and YAG lasers. These wavelengths extend the spectrum from the far infrared to the near infrared. The choice of which type of laser to use is really based on the material that is being marked.

For this article, we will focus on Yb – fiber lasers ranging from 1060 to 1070 nanometers. These are most often used for marking metals, achieving contrast on certain plastics, and removing paint / ink. As the laser sources are essentially the same between the flatbed and galvo units, the actual beam delivery system is the critical decision point.

A quick definition of each type is warranted first. Galvo is short for “galvanometer,” which is a high-speed, high-precision motor used to direct lightning to a location in space. The term “directed beam” is commonly used as a descriptor for this type of laser. The mirrors are mounted on the end of two independent galvo motors and the very fast deflection of the two mirrors working in tandem will cover an area with the focused beam. A special optics called “flat field” lenses allow the beam to be delivered perpendicular to the workpiece over a specified area. The most common field sizes are 4 “square (5.5” in diameter) and 7 “square or 8” in diameter. Generally speaking, the quality of the marking is approximately the same throughout the field.

Flat surface lasers, also known as “gantry” lasers, deliver the beam through an XY tracer system, usually driven by AC or DC servo motors. This is a more common supply type for CO2 lasers, but it is being used extensively with Yb: Fiber lasers and YVO4 Vanadate lasers. The combination of the servo motors and the belt-driven gantry arms allows a large area to be covered. Various gantry-type fiber lasers are available to address areas up to 24 “x 36”. Depending on the delivery style of the plotter, the beam is focused through the center of a single lens and down onto the workpiece. The XY axis then moves the focused beam around the marking area in linear motion (usually in raster mode).

So why is one better than the other? In fact, you cannot say which one is better without using the app or the actual process as your driving indicator. I have had the opportunity to work for companies that supply both types. This is both a blessing and a curse from a salesperson perspective. Most companies that manufacture a flatbed system do not have the experience or knowledge to produce a competitive galvo unit. On the other hand, it’s nice to have every technology to turn to.

So perhaps the first rule of thumb is to consider what the vendor’s key products are. If you manufacture flatbed platforms, rotary recorders, percussion stampers, etc., galvo lasers are probably not your main concern. I work for Electrox, which does nothing more than make directed beam laser marking systems. There are several other companies that operate in the same way, where galvos are their specialty. Likewise, there are a number of companies where flatbed lasers are their bread and butter. When selecting technology, consider the vendor’s knowledge base.

If cycle time is not the main issue, I recommend running samples for evaluation with both technologies. Having marked pieces that can be compared side by side, with different types of lasers is a luxury not to be missed. If brand speed is the key, galvo systems are the only way to go. If your parts are very large, the flatbed system may be preferable, although most galvo suppliers offer a programmable XY table option. Evaluate the price and quality of the brands if this is your situation.

Galvos are much better if the marking is to be “in line”, that is, on an automated production line. Most flat surfaces are not suitable for customization. Flatbed platforms, while slower in processing speed, actually sometimes produce more output when running in batch mode. Batch mode is when you put similar parts into an array and then process them in a row and column format. The relatively slow speed of the platforms will allow the operator to perform other operations in parallel with the marking. One suggestion is to ask your supplier to provide you with a time study based on your exact production requirements.

Fiber lasers, I mean the actual “engine” of the system, are very reliable and durable. Galvo systems require less maintenance than flat surfaces, but this is nominal for both. The longer stroke of the gantry types creates conditions where the belts must be adjusted and alignment is more critical. Still, this is a very easy process and is generally not a problem in production.

Flatbed systems generally work with a more graphics-oriented program like CorelDraw. So if you are doing a lot of image manipulation, logos, photos this may be the best option. If you are interested in variable text such as bar coding, serialization, and date coding, galvo systems are usually superior. Always request a software demo when selecting a laser. Note: I even wrote a previous article on selecting laser marking software. Ease of use is key.

The selection of the team is something that you will have to live with for some time, so it is essential that you evaluate all the options. Make sure you understand what you will be using the laser for now and what you will need it for in the future. We as manufacturers cannot make machines bigger, faster, and easier to use after the fact, so be sure to buy equipment that can grow with you as your business expands.

So in conclusion, never buy strictly by price. Consider all the performance characteristics of each type of beam delivery system and, most importantly, which type will be the most advantageous to you and your business.