Laser marking is a marking method that uses a focused laser beam to alter the surface of a target.

The laser beam is emitted by an oscillator and scanned using a mirror (known as a scanning mirror), and a focusing lens is then used to focus the beam on the target and mark it by altering the surface.

Because laser marking involves using light to change the target surface, this method is more resistant to abrasion than ink-based marking, and the marking does not fade over time.

Laser marking machine also allows automation and processing at high speeds, consequently leaving permanent traceable marks on a wide range of materials. Laser marking allows parts and products to be marked with:

• Texts, including part numbers and serial numbers
• Machine-readable data such as Unique ID codes, 2D Data Matrix codes, barcodes, etc.
• Graphics

The laser marking technology creates lasting marks on component surfaces by generating focused beams of light containing high energy levels. The built-up energy is released in the coherent light beam directed at the material surface using mirrors.

As a result of the light beam interacting with the component’s surface, there is a transfer of heat energy from the beam to the surface. Therefore, the appearance and properties of the material will change. Depending on the energy level, the laser can engrave, etch, anneal, or discolor surfaces with great precision.

The concentrated beam targets only specific areas on the material, ensuring precise, high-contrast, and high-quality marks. These marks are permanent, and you can easily read or scan them on any surface. As a result, this marking process is ideal for operations where permanency and accuracy are critical.

There are several laser marking technologies for different applications out there. Each technique has its benefits and downsides, and your choice will depend on budget, quality requirements, and applications. Let’s examine some of these techniques.

Laser Engraving

This process involves the removal of some materials from components’ surfaces using laser beams. During the process, the material will absorb heat from the laser, melt, and evaporate, creating marks in the form of depressions. The material will also react with air, causing a color change to make the mark more distinctive.

There are no consumables involved in laser engraving. Thus, it attracts low operational costs compared to other engraving methods that use special inks or drill bits. Laser is suited for a wide range of materials, including metals, plastics, and ceramics. Therefore, engineers employ it for many diverse applications.

Laser Etching

This highly versatile process creates marks on workpieces by melting their surfaces. The laser beam produces a raised mark by delivering high amounts of energy to a small, localized area. Consequently, the surface will melt and expand, changing the color to black, gray, or white.

Etching is commonly used for producing permanent markings like serial numbers, data matrix codes, logos, and barcodes. It is also a versatile process ideal for a wide range of metals, including aluminum, lead, steel, magnesium, stainless steel, etc.

Laser Annealing 

In laser annealing, the laser beam will heat the material surface locally to create the mark. The beam only penetrates between 20 to 30 µm into the material surface, thereby resulting in a very minimal change on the surface. The localized heating causes color changes in the material. The marking could be black, red, yellow, or green, depending on the temperature of the heated layer.

The results of laser annealing are permanent abrasion-proof markings. Laser annealing works best on ferrous metals and titanium. Therefore, various industries can use it, ranging from healthcare to automotive, food and beverages, and aerospace industries.

There are many types of laser marking machines you can use for different applications. Each of these laser markers is ideal for different materials and operations. Here, we will discuss the three most common laser markers.

CO2 Laser Markers

A CO2 laser marker is an automatic laser printing system using a gas laser generator with a wavelength of 10.64μm, which uses the high-energy laser beam released by CO2 gas molecules to engrave photo, pattern, text, or line on wood, paper, ABS, PVC, resin, acrylic, leather, glass, ceramic, and rubber. It is equipped with a high-speed scanning galvanometer and a high-precision beam expander focusing system for fine marking.

CO2 laser marking is realized by using the thermal effect of the laser on the material. Or by heating and vaporizing the surface material to expose the deep layer of different colors.

Or by heating the surface of the material with laser energy, it will undergo microscopic physical changes, so that its reflective properties will change significantly.

Or some chemical reactions that occur when heated by laser energy, displaying etched graphics and text information. With a conveyor belt, it can mark on the fly, with a rotary attachment, it can engrave a cylinder, and with an XY moving table, it can achieve automatic segmentation and etching of large areas.

Fiber Laser Makers

A fiber laser engraver is a type of professional laser marking system used to use the laser energy to remove layers and change the appearance metals, plastics and glass fibers to create permanent text and patterns. A fiber laser marking machine is composed of laser generator, galvanometer scanner, and control card.

It features with small size,good beam quality, automatic follow-up, no consumable materials, no pollution, no noise, low-cost, maintenance-free, energy saving and environmental protection. 20W and 30W laser powers are used for shallow engraving. 50W, 60W, and 100W laser powers are able to do deep engraving.

MOPA laser generators are used for color engraving on stainless steel, titanium, and chromium. Rotary attachment is optional for rotary engraving on cups, rings, and cylinders. Belt conveyor is optional for industrial assembly line production with online flying marking system.

UV Laser Markers

An UV laser marking machine is a cold laser engraving system that uses a 355nm ultraviolet laser generator to etch the surface and subsurface of plastic, glass, and crystal. It can be used for the rotary marking of cylinders, and it can also be used for on-the-fly marking with the assembly line. Like a chemical etching method, it is possible to engrave the interior of crystal and glass with a UV laser.

The ultraviolet laser generator adopts frequency doubling technology to convert the infrared laser beam of 1064nm wavelength emitted by the solid-state laser generator into a 355nm (triple frequency) or 266nm (quadruple frequency) ultraviolet laser, also known as blue laser. Its photon energy is large, which can match the energy level of some chemical bonds (ionic bonds, covalent bonds, metal bonds) of almost all substances in nature, directly breaking the chemical bonds, causing the material to undergo a photochemical reaction without obvious thermal effect, so it is called cold working.

It has good beam quality (fundamental mode output), smaller focusing spot (diameter less than 3um, divergence angle is 1/4 of that of fiber-pumped laser), minimal thermal effect, no thermal effect, and can reduce the mechanical deformation of materials , and will not cause the problem of substrate scorching.

For laser marking machines of the same specification, the price from high to low is: UV laser marking machine, fiber laser marking machine and CO2 laser marking machine.

1. UV laser marking machine is used for ultra-fine marking, and the price is expensive, about $7000 to $20002.
2. Fiber laser marking machines mainly work on metals, with the largest number of users, and the price ranges from $3000 to $20000.
3. CO2 laser marking machine can only be used to mark non-metallic materials, and the price is $2000 to $5000.
4. Laser engraving machine with large working area will cost $3000 to $6000.

Laser marking machines can create marks like serial numbers, barcodes, and graphics. When choosing a laser marking machine, there are several things you should consider.

Here are three key considerations you need to know about.

1.Is a UV or fiber laser marking machine better for your requirements?

The two main types of laser marking machines are UV laser machines and fiber laser machines. Both look similar and both can engrave numerous materials. But a UV laser marking machine can engrave more materials than a fiber laser machine. However, a UV machine has less power for carving and engraving over metal materials.

Although the two types of machines look similar on the outside, the technology they use is different. They use different power suppliers and the UV laser must be refrigerated by a water chiller while the fiber laser is refrigerated by air.

The UV laser technology also allows for greater multifunctionality and capacity for marking over different materials, including non-metals, and it uses an automatization system such as linear guide engraving and rotary engraving.

Although a UV laser marking system has many advantages over a fiber laser machine process and is the most widely-used form of laser marking, fiber laser marking does have many benefits, including its ability to carve at high speed on a wide variety of metal surfaces.

2.Which materials do you want to mark?

Seeing as a UV laser marking machine can mark more materials, it is often the preferred choice. But your choice of machine will largely be dependent on the exact materials you need to engrave. Here are the key materials you can use with each machine.

Common UV laser applications

UV lasers can mark:
· Some metals
· Some stones
· All plastics
· All glass
· All papers
· All leathers
· All woods
· All ceramics

Common fiber laser applications

Fiber lasers can mark:
· All metals
· Some plastics
· Some stones
· Some leathers
· Some paper

The possible use-cases of laser markings continue to increase, thanks to the ever-developing technology. Therefore, laser marking processes now find applications in an extensive range of industries.

Many industrial and commercial products require labeling. These products include machine tools, integrated circuits, keyboard buttons, food packings, medical equipment, printed circuit boards, and many more. Laser marking helps create these labels, including model and serial numbers, QR codes, bar codes, part numbers, logos, dates, etc.

Traceable information is often required for quality control. Laser marking also helps to create permanent identification markers on various components. Examples include silicon wafers for photovoltaic cells, indications on electronics, smart cards on automotive parts, and more. This way, you can easily trace back and solve possible problems quickly.