A Comprehensive Guide to Laser Engraving
A guide to everything you need to know about laser engraving.
Laser engraving is a process used in marking materials with a laser beam. It is used in the automotive, medical, and manufacturing industries while also being extensively used for artistic or aesthetic applications. In most cases, engraving is used because of its ability to produce durable, high-contrast markings.
This article will describe what laser engraving is, how it works, what materials should and shouldn’t be engraved, and the best choice for an inexpensive laser engraving machine to use if you are just getting started with laser engraving.
What Is Laser Engraving?
Laser engraving is a noncontact process that can create easily visible markings on a variety of materials by making use of a laser beam. It can reproduce highly intricate designs due to the fact that the beam is focused to a spot size of as small as a few microns depending on the focal point settings. Laser engraving is often used to produce artistic designs, signboards, industrial labels, and personalized apparel. The laser engraving process produces high contrast between the engraved and unengraved portions of a design, as can be seen in Figure 1 below:
Laser engraved wooden box.
Image Credit: Shutterstock.com/Fairuzee Ramlee
What Kind of Laser Is Used for Laser Engraving?
Laser engraving is most commonly performed with either a CO2 or a fiber laser. Both of these lasers can produce high enough energy densities to engrave a design on a target surface by vaporizing and removing material in a controlled pattern. Fiber lasers are more effective at engraving metals since most metals readily absorb their wavelength. CO2 lasers are better suited for engraving nonmetals such as plastics, stone, and wood since these materials better absorb their wavelength.
How Does Laser Engraving Work?
Laser engraving produces an embossed pattern on a material’s surface through the precise application of high levels of heat by means of a laser beam. The path, power, and speed of the laser beam are controlled by a computer program. The laser can generate very high energy densities, which can remove material from the surface of a material in the exact pattern required. Depending on the settings and programming of the laser, the resulting pattern may leave behind a pattern raised from its surroundings (convex), a pattern depressed into the surface (concave), or a darkened area essentially flush with the surface.
The process by which the laser removes material may be melting + vaporizing, direct sublimation from solid to gas, or, more generally, ablation. Ablation can refer to any erosive process that removes material from a substrate. In the field of laser engraving, it usually refers to material removal resulting from short pulses of laser energy. This energy briefly heats atoms on the surface into a plasma, generating shockwaves that eject small particles from the surface along the desired path. The laser power needed to engrave a particular material depends on several factors:
- Reflectivity: Reflective materials such as metals require higher laser power because not all of the laser energy is absorbed for heating.
- Density: The denser a material, the more molecules must be heated above a temperature threshold to mark the material. This requires more heat and, therefore, more laser power.
- State Transition Temperatures: The higher the melting, sublimation, and plasma generation temperatures of a material, the more laser power is required to heat a unit of material to the required condition for engraving.
Where Is Laser Engraving Commonly Used?
Laser engraving is used wherever durable, high contrast, mechanically durable markings are required, including the automotive, medical, electronics, and aerospace industries. Typical applications can include: durable signage, product marking, artistic engraving for commemorative items, and PCB (printed circuit board) marking. The engraving process is also employed to remove material from rusted metal parts.
What Are the Types of Laser Engraving?
Laser engraving can generally be broken down into three categories: laser ablation, concave engraving, and convex engraving. These are described in more detail below:
1. Laser Ablation
Laser ablation refers to the mechanism by which the material is removed during laser engraving. When a laser beam interacts with the material at a specific power level, it instantly heats up. The addition of heat is rapid enough that the surface does not have time to transition from solid to a liquid but instead is directly vaporized. At higher laser intensities, the ablated material is converted into plasma. Due to the creation of fumes during the process, sufficient fume extraction is required. Laser ablation can be used for both concave and convex engraving techniques. For more information, see our guide on What is Laser Ablation?.
2. Concave Engraving
Concave engraving refers to a laser engraving technique that makes use of laser ablation in order to remove material in the shape of a desired pattern or design. This process produces a design that is indented relative to the surface of the surrounding, untouched material.
3. Convex Engraving
Convex engraving refers to a laser engraving technique that also makes use of laser ablation to remove material. Unlike concave engraving, convex engraving does not directly engrave the design but instead engraves all the areas around the outline of the design. This produces an embossed design that is raised above the surrounding engraved areas. For more information, see our guide on What is Convex Engraving?.
What Are the Materials That Can Be Laser Engraved?
Laser engraving can be performed on a wide range of materials, provided the laser is powerful enough to vaporize the material. Listed below are some common materials used for engraving:
- Marble and Granite: Marble and granite are often engraved for items like tombstones or awards. They produce excellent contrast between the design and background when engraved.
- Stone and Brick: Stone and brick are often engraved for artistic products.
- Wood: Wood is easily engraved due to its low ablation point and low cost. It is a popular choice for hobbyists and is used for signs and artistic designs.
- Glass: Glass engraving is typically performed on awards and trophies. It can also be used to artistically mark wine glasses and other glass crockery.
- Acrylic: Acrylic is a highly transparent plastic that is used as a lighter and cheaper substitute for glass. It is also used for awards and trophies.
- Metal: Metal parts are typically engraved for permanent and durable part identification.
- Cardboard and Paper: Cardboard and paper can be engraved with very low-power laser engravers. They are used for creating artistic items like commemorative or congratulatory cards.
- Fabric: Fabrics are engraved to give clothing an artistic, distressed look. This process is often used on the denim material used to make jeans.
- Leather: Leather is typically engraved for personalized consumer items like wallets, belts, and shoes.
What Are the Materials to Avoid for Laser Engraving?
Laser engraving can be performed on a wide range of different materials. However, some materials should be completely avoided, as listed below:
- Polyvinyl Chloride (PVC): When vaporized, PVC produces chlorine gas, which is extremely dangerous if inhaled. It can also cause significant damage to the laser machine itself.
- Polyvinyl Butyral (PVB): This is an optically clear resin that is often used to laminate glass sheets. The fumes produced during engraving PVB can be toxic.
- Polytetrafluoroethylene (PTFE /Teflon™): Teflon™ can produce perfluorooctanoic acid if heated above 300 °C. This chemical produces a range of negative health effects during long-term exposure.
- Materials Containing Halogens, Epoxy, or Phenolic Resins: Laminated fiberglass and carbon fiber often contain resins. These resins produce harmful fumes if heated, and must therefore be avoided.
- Carbon Fibers: Carbon fibers are laminated with various epoxy resins that produce toxic fumes if vaporized.
- Artificial Leather That Contains Chromium (VI): Chromium VI (or hexavalent chromium) is a known carcinogen. The fumes created during laser engraving are, therefore, extremely dangerous.
- Beryllium Oxide: This material has exceptional thermal conductivity. This alone makes it difficult to engrave. But it is also very toxic. Inhaling fumes containing beryllium can also result in a range of negative health effects, such as lung disease.
The materials listed above should be avoided, as they can pose significant health risks if the workspace is not properly ventilated. Even if vented, local environmental regulations may require additional fume-suppressing procedures, such as water scrubbing for example.
How to Laser Engrave?
Laser engraving is a multi-step process, as described in detail below:
- Prepare the Design: Convert the design into a format that can be read by the laser cutter CAM (computer-aided manufacturing) software. This is usually a .dxf file or some other vector-based format. Some CAM packages can directly convert image formats into laser paths. The laser power, speed, and the number of passes are selected in this CAM software.
- Select the Material: The types of materials that can be engraved depends on the type and power of the available laser engraver.
- Fixture the Workpiece: Place the material into the laser engraver and ensure that it cannot move during processing.
- Create a Safe Work Environment: Ensure that there is sufficient ventilation and that the correct protective eye goggles are used.
- Engraving: Some laser engraving machines will automatically focus the laser. However, in some cases, this must be done manually prior to engraving.
- Finishing: Once the part is complete, it can be removed from the machine and cleaned.
What Are the Things To Consider When Laser Engraving?
When laser engraving, the most important thing to consider is safety. Ensure that the materials being engraved do not produce carcinogenic or toxic fumes. In most cases, ventilation will be required even if the fumes are not particularly harmful. Ensure that correct eye protection is worn, as reflected laser light can permanently damage the eyes.
On a technical level, it is important to understand the relationship between laser engraving effectiveness and laser power. Engraving is a high-energy process that vaporizes material, and some dense or reflective materials like metal require higher-powered lasers.
What Is the Best Cheapest Laser Engraving Machines?
“Cheap” is a relative term. However, for the person looking to get started in laser engraving, the most commonly recommended low-cost engraver is the Ortur LM2 Pro S2 Laser. It can be purchased for under $500. Its normal retail price is listed as $600. This laser engraver can engrave wood, leather, and even stone while also being able to cut materials like paper and cardboard.
What Is the Average Price of Laser Engraving Machines?
There is a large price difference between entry-level and industrial-grade laser engraving machines. Entry-level laser engravers can be purchased for $500 to $1000, while industrial laser engravers can cost $20,000 or more. Note that some laser cutters can also be used to engrave by reducing the laser power.
What Is the Difference Between Laser Engraving and Etching?
Laser engraving removes material in the shape of the design to produce either an embossed or indented effect, i.e. the design has a 3-dimensional structure. Laser etching simply marks a 2D design on the surface of the material and uses significantly less power. For more information, see our guide on Laser Engraving vs Laser Etching.
Which Is Safer Between Laser Engraving and Etching?
Both laser engraving and laser etching make use of laser beams that pose a burn and eye damage risk. Laser etching can be considered safer due to its lower power requirements, as well as the fact that it produces significantly fewer fumes.
Is Laser Engraving the Same as Laser Cutting?
No, laser engraving is not the same as laser cutting. Engraving removes material from the surface of a part in a controlled pattern. Cutting passes the laser beam through the entire thickness of a part, separating material into multiple pieces following either a simple cut line or a complex pattern.
Does Laser Engraving Use the Same Machine as Laser Cutting?
Yes, laser engraving can often be performed on the same machine as laser cutting by using a lower power level. Both processes are based on the same fundamental technology.
Is There a Laser Engraving Tool?
Yes, there is a laser engraving tool. This is basically a machine that moves a laser head around a 2-dimensional plane to engrave a design, as instructed by a set of commands generated by CAM software.
This article presented laser engraving, explained what it is, and discussed everything there is to know about the process. To learn more about laser engraving, contact a Xometry representative.
Xometry provides a wide range of manufacturing capabilities, including sheet cutting and other value-added services for all of your prototyping and production needs. Visit our website to learn more or to request a free, no-obligation quote.
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