Laser marking is a revolutionary technology that is currently used for a very wide variety of applications.
It is applicable in many forms, from engraving, annealing, foaming to staining and removing techniques.
To choose what technique and what machine to use for each desired application is what most people have to worry about.
This is because different surfaces have different requirements, and different machines have been designed for use in different ways.
So take some 10 minutes of your time and let Heatsign Marking show you how to distinguish the type of machine you need for your applications.
What is Laser Marking?
Laser marking is the process that labels a material using a focused laser beam. When the laser beam interacts with the surface of the material, it alters the appearance of the marked area to display a desired design.
This is achieved through discoloration, which happens when the low-powered laser beam hits the marked area. Laser marking makes it possible to create high-contrast high-precision marks without disrupting the surface of the actual material.
This is the main difference between laser marking and laser engraving, which is a subtractive process that leaves indentations on the surface.
What this article is all about
The purchase of a laser marking machine need not feel or look technical at all.
In fact, most marketing pitches simply overwhelm potential buyers with details they do not need when making a choice to buy laser marking machines.
However, you almost always must research to establish the choice of machine that best suits your needs.
There are five main types of laser markers;
- Fiber laser machines,
- Green laser machines,
- UV laser machines,
- CO2 laser machines,
- Mopa laser machines.
The type of machines you require for different materials will be different. This is because laser engraving can be done on many types of materials including various types of metal, plastic, glass, wood, paper, ceramic and even stones.
Selecting the wrong equipment to buy can therefore be a painful and expensive process.
This is more so if you haven’t accurately figured out what you need, because of the time, transportation and warranty issues that may arise when you want to change to the right machine you require.
A quick look at the technology
The term laser is basically an acronym for ‘Light Amplification by Stimulated Emission of Radiation.
Lasers have three distinct properties that are together used to make permanent marking on a wide variety of materials possible;
- Highly Monochromatic beams; this means that the beams consist of light waves that are from one precise single wavelength
- Outstanding Directivity; this means that the beams have parallel light waves that don’t collide or spread as they travel over distance
- High Coherence; which means that the waves are in phase with one another.
A laser engraving machine consists of three main parts, namely a laser, a controller, and a surface. The laser operates like a pencil emitting a high quality monochromatic beam that allows the controller to trace patterns onto the surface. The controller manages the direction, intensity, speed, and spread of the laser beam while it works on the surface.
There are three main types of engraving techniques employed by the various types of laser engravers.
They include the X-Y table, the cylindrical technique and the galvo mirror technique.
The X-Y Table
The most common technique is the X-Y table. In this technique, most models have the work-piece (surface) stationary and the laser optics move around it in X and Y directions, drawing vectors on the surface. Other models have variations where the laser is stationary and the work-piece moves, or the work piece moves in the X axis and the laser moves in the Y axis, and vice versa. This is what is known as the vector mode.
Cylindrical Laser Marking
This technique is for cylindrical work-pieces like pipes (or flat work-pieces mounted around a cylinder). In this technique, the laser traverses a fine helix, usually on a rotating cylinder, with an on/off laser pulsing that produces the desired image on a raster basis.
In the third method, both the laser and work-piece are stationary. Galvo mirrors use a reflective mechanism to move the laser beam over the work-piece surface. Laser engravers using this technology can work in either raster or vector mode.
The Marking Point
This is the point where the laser beam touches the working surface. It should always be on the focal plane of the laser’s optical system, usually the same as the laser beam’s focal point. This point is typically very small, perhaps less than a fraction of a millimeter. It is typically characteristic of the optical wavelength of the beam, and only material within it is significantly affected when the laser beam hits the surface.
The energy delivered by the laser changes the chemical structure or vaporizes the material at the focal point, thus revealing the intended marking.
The main difference in the types of laser machines used in marking applications is the wavelengths that each supports, and power, which determines the speed of operation.
Different wavelengths mean that different types of machines will be suitable for different marking surfaces.
However, in general, laser marking systems have distinct advantages over other types of marking.
They offer reduced downtime, eliminate or highly reduce the use of consumables, create high contrast and permanent marks and end up giving you reduced preventive maintenance and costs.
Factors to be included in evaluating the correct Laser Marking System
When choosing the ideal model you want for your intended use, the following are the best things to take into consideration;
Moving or stationary marking surfaces
If you need a machine to be included into a processing line for continuous processing of parts, models that can accord part marking of moving parts, at a pre-determined speed are a great choice as they provide high in-process efficiencies.
Due to the varying properties of laser wavelengths and power, different systems will give different results depending on the speed with which part production is happening. High speed production lines will need high wattage markers in order to effectively mark all in-process parts.
Material to be marked
As we shall see later, laser markers can work on a wide variety of surfaces. The marker you use will depend heavily on the marked materials you want to work on. For example, fiber lasers are very good with metals, while CO2 lasers are great with non-metals.
Some machines are sensitive to work environments that have a high propensity for dust, shock and vibrations, while others are robust and can withstand these environments.
Some laser machines are low speed, and may not work well with high workloads. For example, when marking metals, it could be more cost effective in the long run to work with fiber lasers than with CO2 lasers.
After Sale Services provided
Sometimes, machine set up and operation can be tricky. Though most laser markers are relatively low maintenance with long lives, working with a supplier who has local expertise or who can provide instant assistance is a good consideration when choosing which equipment to buy.
Understanding the five types of laser markers
Fiber laser marking technology has risen in recent times to be one of the most sought after direct part marking technologies the world over.
With power levels ranging from 20-50 watts, Fiber Laser Marking machines are some of the most powerful laser marking machines in the market.
These machines are ideal for depth etching or engraving, with great results on harder metals or when one needs high powered systems with a smaller spot size to achieve high resolution.
High beam quality and small spot sizes with larger lenses allows fiber laser to be used for small-component batch marking applications or the cutting of very thin metals.
There are several ways in which you can use fiber lasers.
This is the kind of marking done to cause different shades of colors on a material by varying the speed, power, frequency and pulse width. The best results on color marking are achieved on stainless steel and aluminum, especially if you have a mopa fiber laser marker.
Another form of color marking is color removal, where you can mark by removing color on coated materials to reveal an underlying material of a different color. This technology is mostly used for fittings, labels and packaging materials.
This is the hardening of a metal surface using a laser which also enables various types of colors to be produced in what is known as color laser marking. Various shades of green, red and yellow can be achieved in this process with various materials.
Involves the kind of treatment that leaves the targeted area lighter than the rest of the part being processed.
Carbonizing is the destruction of carbon bonds to create shades of darker marked areas without affecting the surface of the material. It is mostly used for light plastics and organic materials.
Night and day marking:
Fiber laser technology can be used to deliver marks that are easily legible in day time and illuminated by night. This can be useful for such applications like use on dashboards, reflectors, number plates, watches, Health and safety and door signs.
The fiber laser markers produce excellent beam quality that is usable on a wide variety of surfaces. Because of the high level of filtration of monochromatic light beams, varying the power of a single type of beam can allow you to work on many types of surfaces.
Fiber laser markers are highly durable.
Some models are built in modular designs, giving very high flexibility on the marking area they can work on, and the ability to work well with complex marking surfaces.
They usually have economic power usage, with a photoelectric conversion rate of about 25%, which is one of the best in the industry.
You can achieve different depths of laser engraving, depending on the intended purpose by varying the wattage of the selected machines.
Fiber laser markers are also some of the fastest marking machines you can use.
When mark some material which is very thick or high reflection, it cannot work fast. It also can not do very deep engraving on most metals.
Green Laser Marking machines are designed to mark highly reflective materials. They also work on or highly sensitive substrates like silicon wafers, exhibiting very good work ease and high precision. They operate in the green Near-IR visible light spectrum (at 532 nm) and power ranges of 5-10 watts.
They are perfect for soft plastics, PCB Boards, Integrated Circuit Chips and for scribing or marking of Solar Cells of various material compositions.
The inherent advantages of the 532 nm wavelength include greater absorption across a many types of materials, and mitigated thermal energy allowing it to mark substrates that other higher wavelength simply cannot. Green Laser markers also give very tight spot sizes of up to 10 µm.
- Green laser markers achieve very high precisions that allow micro-marking of fonts that are less that 1mm with very small widths of up to 10 µm.
- The achieve very low thermal transfer to work surfaces, which is ideal for highly sensitive materials.
- The green laser markers are ideal for marking semi-conductors, PCB, ceramics and epoxy resins.
- They can be used in coating removal marking with thin layer coating, working on materials that do not react to other forms of Infrared beams.
- The robust mechanical and optical design allow the machines to work in high speed industrial environments where dust, shock and vibration are common.
- They are expensive and not ideal for depth marking.
Ultraviolet (UV) represents a band of the electromagnetic spectrum with wavelength from 10 nm to 400 nm. They are shorter than those of visible light but longer than X-rays.
Long wavelength UV is not considered an ionizing radiation, because its photons do not have the energy to ionize atoms. However, it can cause chemical reactions that make substances glow or fluoresce.
As a result, the chemical and biological effects of UV are much wider than simple heating, and many practical applications of UV radiation are possible due to its interactions with organic molecules.
Gas lasers, solid state lasers and diodes can be used to make machines that emit ultraviolet rays, and lasers are available which cover the entire UV range.
Since the excimer laser was discovered, it has been possible to avail intense ultraviolet light. Researchers explored and uncovered the unique properties of this new light source. As various phenomena involving UV energy and material interactions were discovered and optimized, practical applications emerged.
UV Laser marking machines are a manifestation of this technology.
They are usually designed in the 355 UV laser wavelength and can mark a wide range of materials. They are perfect for “cold marking” applications, where lasers producing heat is not applicable. UVC, can mark materials like plastics, ceramics and glass without the need of additives. Due to the high quality beam, UVCs can micro-mark electronics, circuit boards and microchips. They are also superb for use on solar panels and precise medical equipment marking (e.g. marking measuring cylinders and syringes).
Used in the medical and pharmaceutical industry to mark low heat tolerant equipment like plastics.
Used in the electronic industry to mark circuit boards and microchips with high quality <1mm fonts.
Can mark glass without risk of micro-fracture
UVCs are efficient in power usage
- UV laser marking machines are not good for metal deep etching or engraving.
- UV Laser machines is very expensive. The industrial machines are going for as much as $20,000.
CO2 laser marking machines are usually sealed-tube laser marking systems with galvo-steered beams designed for marking non-metal surfaces like wood, glass, quartz, and ceramics. They can also mark fabrics and other organic materials, operating at wavelengths of 10,600nm.
These machines are used to produce barcodes, serial numbers, and logos on metals and other surfaces.
When laser marking bare metal using a CO2 laser, a special marking agent (spray or paste) is used to treat the metal prior to engraving. Once the laser beam is applied, the heat from the laser bonds the marking agent to the metal, resulting in a high contrast permanent mark.
The machines are fast and affordable. They are among the oldest type of engravers and markers, and can also mark organic materials such as wood, ceramics such as tiles, stones and more.
CO2 laser systems can be operated from a wide range of applications like Windows and Linus, and are very easy to use.
The CO2 lasers are largely used in food, drug, or alcohol packaging, integrated circuits, electrical appliances, mobile communications, microchips and electronic components.
Due to their wavelength, sealed-off CO2 laser sources achieve best marking results on organic materials like wood, paper or leather and certain plastic polymers. CO2 lasers are also suitable for some glass marking.
Good For Coated metals, such as paint aluminum or painted brass, do not require pre-treatment.
CO2 lasers are best suited for non-metals, producing good markings on materials such as wood, leather, paper, plastics, glass, ceramics and acrylics.
If you want a CO2 laser machine with big power, it can be very expensive. There are offers for these machines ranging from $1400 to $10,000 on Amazon.
The photoelectric conversion rate in the process is only 10%, and energy consumption is high.
CO2 laser marking machines exhibit significantly lower throughputs than fiber lasers when working with metals. This is because time is required for the coating or pre-treating with a metal marking agent.
Co2 Laser Glass tube working life is less than 2000 hours, Metal RF CO2 laser tube working life will be more than 20,000 hours but price is high.
CO2 lasers are also costlier to maintain, and the operation requirement is higher.
MOPA Laser Marking Machines are very similar in design and outlook to fiber laser markers.
However, the internal technology is different, giving different capabilities.
MOPA machines gives a high power efficiency by use of the Master Oscillator Power Amplifier approach. In this technology, the “MO” produces a highly coherent beam, and an optical “A” is used to increase the power of the beam while preserving its main properties. It can reach amplitudes of up to 2700KHZ, compared to the Q-switched (fiber laser) option which only goes up to 500KHZ.
The master oscillator has no need to be powerful, and has no need to operate at high efficiency because the efficiency is determined mainly by the power amplifier.
Several laser power amplifiers can be seeded by a common master oscillator, which can give good versatility in a production facility.
These machines achieve great results with reproducible multiple-color marking on stainless steel, high contrast black marking on anodized aluminum and high contrast marking on plastics.
Since most mobile phone casings are made of anodized aluminum, the MOPA laser is mainly used to emblazon high contrast IMEI and barcode numbers on the casings.
Handcraft manufacturers can also produce very beautiful designs using green, pink, purple, blue, red and black colors on stainless steel.
As MOPA laser can adjust the pulse width to achieve different marking results, then it will also be a good choice for plastic marking.
- Can mark stainless steel in different colors.
- You will achieve less burning or melting in the edge area of the worked surfaces especially during engraving.
- Less heat development during annealing markings on metal, which leads to a better corrosion behavior, tensile strength and durability of parts.
- Gives more homogeneous and sometimes higher-contrast markings on some plastics.
- Gives you less foaming when working with plastics
MOPA technology has been around for quite some time, but research is still going on in the field, hence the best machines are yet to be designed.
MOPA machines almost always tend to be more expensive that Q-switched fiber laser markers.
Wood, glass and some types of plastics are just never going to work with MOPA lasers, as is the case with Q-switched or fixed pulse markers.
Variable pulse width lasers cost more are much more complicated to work with for the following reason: Finding the correct power, speed, pulse frequency and line fill settings for any material with a MOPA laser can be a challenge.
Equipped with the tips you have gathered in this article, it is now possible for you to do a cursory glance and the work you want to do with laser markers, and decide which type of machine to buy.
From there, it is now a matter of choosing the models that give you the best options in terms of pocket friendliness, features, mobility, after sale services etc.
Fiber lasers are great with metals, CO2 lasers are best with non-metals. UV laser markers are great for creating fluorescent marking on low heat tolerant materials like soft plastics, while the MOPA gives versatility with color marking on stainless steel, and black marking on anodized aluminum.
This article is created by HeatSign, one of the leading Chinese brands in marking technologies.