Laser cleaning solutions are becoming the norm in industrial applications. The capabilities of laser cleaning solutions are unmatchable by alternative cleaning processes. Laser cleaning systems serve aesthetic, functional, and physical purposes.
Therefore, professionals new to the technology often ask, 'what is laser cleaning?' Understanding the capabilities of laser cleaning can improve the outcome of any manufacturing process.
This article will have an in-depth discussion on the concept of laser cleaning. You will learn the working process of laser cleaning machines, different methods, types, parameters, and much more valuable information.
What is Laser Cleaning?
Laser cleaning is a form of laser ablation that uses a high-energy light beam to remove contaminants from a material's surface. Laser stands for Light Amplification by Stimulated Emission of Radiation.
The laser cleaning process uses short laser pulses. The pulse is high frequency to increase its stored energy. Additionally, the beam diameter is focused on a very small area.
When high-power lasers strike a contaminated surface, the contaminants absorb the stored energy. High-energy lasers vaporize the contaminant particles when they come in contact. This results in the complete removal of contaminants from the surface. Common contaminants include oxides, oils, phosphates, paint, or any other unwanted material layers.
The focused laser beam can be controlled to move over the required areas of the material. In this manner, it can provide a straightforward cleaning operation, leaving out any sensitive areas that do not require cleaning.
Who invented Laser Cleaning?
JF Asmus invented laser cleaning technology in 1973. He proposed laser cleaning as a way to restore artwork. However, the laser technology at the time was quite restricted. The development of laser technology, combined with the ideas of JF Asmus, led to the laser cleaning technology of today.
How Does Laser Cleaning Work?
The process of laser cleaning is based on the physics of light amplification and energy released through these rays. There are various steps involved from preparation to post-treatment. Let us study these steps one by one:
What is the process of laser cleaning?
1. Pre-requisites
Before starting the laser cleaning process, it is vital to know the laser ablation threshold of the unwanted material. The ablation threshold is the minimum energy limit of the laser over which the unwanted material will vaporize. The ablation threshold varies across materials such as oxides, rust, paint, and oils. Therefore, knowing this value for the particular material you wish to remove is essential.
Shooting the laser beam below the ablation threshold will not have any effect. Keeping the laser beam too far beyond the ablation threshold can harm the primary workpiece. Therefore, the value of laser energy should be slightly above the ablation threshold. Additionally, the difference between the ablation thresholds of unwanted material and the underlying surface should be sufficiently significant.
2. Laser Setup
Every laser cleaning machine comes with its own setup guidelines. Read your machine's manual to know how to get it ready. It is crucial to have eye protection beyond this point.
3. Beam Delivery
The laser beam is pointed toward the workpiece material. The beam is sent in short bursts instead of a long exposure. The delivery method and movement of the laser depend on the type of laser cleaning system being used. Certain laser systems can scan the workpiece for areas that require cleaning. The operator can adjust the scanning speed.
4. Plume Extraction
When a large number of contaminant particles is removed, vapor rises. The plume can block the laser beam and settle on the workpiece again. Therefore, the plume extraction process takes place. A dust-blowing mechanism prevents the plume from settling again or blocking the laser cleaning process.
5. Inspection
A workpiece inspection is conducted to determine whether the task has been completed successfully. If any contamination is found, the workpiece undergoes a repeat cycle of laser cleaning.
6. Post Treatment
Once cleaning is complete, the workpiece goes for secondary treatment processes. Secondary treatment is optional and depends on the job's requirements. For instance, the workpiece should be coated with anti-corrosion layers after rust is removed by laser cleaning. This prevents future contamination with rust.
Laser Cleaning Modes
There are two modes of laser cleaning operation:
Pulsed Laser Cleaning: Pulsed laser cleaning uses a high-frequency alternating laser beam for cleaning. The pulsed laser beam provides a short burst of energy to the contaminant, removing it instantly. Pulsed laser cleaning is the preferred mode.
Continuous Laser Cleaning: The part is exposed to the laser beam for a more extended period. This results in a deeper cleaning of the workpiece. However, it risks overheating the underlying material and damaging it.
What are the Different Methods of Laser Cleaning Processes?
There are two methods for executing laser cleaning technology. These are:
Dry Laser Cleaning
Dry laser cleaning directly irradiates the surface with the laser beam. Laser ablation of contaminants occurs. Contaminant particles vaporize and are removed from the surface. Dry laser cleaning works well for surface cleaning of sensitive materials, such as artwork.
Wet Laser Cleaning
Wet laser cleaning starts by applying a liquid layer on the surface. After that, laser ablation begins. The laser beam heats and vaporizes the liquid layer. Vaporization of the fluid film causes shock to the contaminants, dislodging them from the surface. A significant requirement for wet laser cleaning systems is that the contaminants do not react with the liquid film. It can trigger unwanted chemical reactions and make cleaning more difficult.
What are the Different Types of Laser Cleaning Machines?
Many different types of laser cleaning systems are available to suit various requirements. Let us discuss these types of laser cleaning machines one by one:
- Handheld Laser Cleaner: A handheld laser cleaner is a small device that can be held and operated manually. The laser delivery device is connected to a control unit. The control unit is a little bulky but still portable and manageable.
- Conveyor Laser Cleaner: A Conveyor laser cleaning machine has a laser device mounted on the conveyor. The workpiece automatically feeds into the laser, and the entire surface can be scanned and cleaned within the laser compartment. These machines fit well into the assembly production line, where products move on conveyors. A typical example is the automotive industry.
- Robotic Laser Cleaner: A Robotic laser cleaner has beam-delivery systems mounted on the robot's arms. Another option is to use Computer Numerical Control (CNC) to control the laser's movement around the part.
- Enclosed Laser System: An enclosed laser system features an enclosure that confines the part for laser cleaning. The operator cannot access the part during the cleaning operation. This increases the workforce's safety during the process.
Types of Laser Based on Emission Source
Lasers can be classified into many types based on their source and emission method. These various types of lasers are:
- CO2 Laser: In a CO2 laser, an electric current passes through a Carbon Dioxide (CO2) gas chamber. This results in the emission of a visible laser. It is one of the most common types of laser emission systems. These lasers are a subtype of gas lasers. Other alternatives for CO2 are helium-neon, argon, and krypton.
- Solid-State Laser: A solid-state laser replaces the gaseous CO2 medium with a crystal. The crystal contains glass or ruby, mixed with a rare-earth material such as chromium, neodymium, or erbium. Neodymium-doped Yttrium Aluminum Garnet (Nd: YAG) is a typical example of such a laser.
- Fiber Laser: A Fiber laser has a silica-based optical fiber as the medium. The fiber also contains traces of rare-earth material. A fiber laser can be highly focused on a very small area. These lasers are smaller in size. Additionally, they operate at low cost. It is the most preferred emission type in laser cleaning.
- Semiconductor Laser: A Semiconductor laser is also known as a direct diode laser. It uses a special diode that can undergo spontaneous emission. The diode emits a laser beam when current is applied.
What are the Advantages of Laser Cleaning?
Laser cleaning offers many benefits compared to other alternatives. Six main laser cleaning advantages are:
- Selective Cleaning: Laser cleaning can target the contaminant layer that requires removal. The underlying material will always be unharmed by the process.
- Consumable Free: No solvents or chemicals are required for laser cleaning. It is an entirely consumable-free process.
- Versatile: Laser cleaning is highly versatile. It can apply to all types of materials. The important thing is to know the ablation threshold.
- Speed: Laser cleaning is a high-speed process. There is no drying time or waiting period, unlike chemical cleaning. Additionally, the speed of high-power lasers can clean any material within seconds.
- High-quality Results: Laser cleaning efficiently cleans the surface, providing a very high-quality surface finish.
- Material Integrity: The material integrity remains preserved in laser cleaning. This is because the laser only interacts with the contaminant, and its energy is too low to harm the underlying metal.
What Parts Can a Laser Clean?
Laser cleaners are used to remove a wide range of unwanted particles from metal surfaces. Some common examples are:
- Rust: Laser rust removal is one of the most common laser cleaning applications. Lasers can remove corrosion contamination on all types of metal surfaces.
- Paint: Laser cleaning is a great way to remove paint when repainting surfaces. Chemical paint cleaning often degrades the underlying metal.
- Grease and Oil: Contaminant removal is a common requirement for all types of surfaces. Laser surface cleaning can clean these materials without contact.
- Dirt: Dirt accumulates on all surfaces. Laser cleaning removes dirt particles without requiring manual dusting or wiping.
- Adhesive Bonding: Adhesive bonding residue is difficult to remove without chemical products. Laser cleaning is the best method for removing adhesive bonds without chemical products.
- Historical Artifacts: Historical artifacts are sensitive to damage. Laser cleaning provides precise cleaning of these pieces without damaging them.
- PCBs: Electronic parts like PCBs are sensitive to fluids due to the electrical faults they can create. A laser is a great way to clean electronic components without causing electrical failure.
Besides the parts above, laser cleaners can use many other objects. These are:
- Medical equipment
- Glassware
- Optics
- Automotive industry parts
What Materials Can a Laser Clean?
Laser cleaning can clean a lot of different materials, like:
- Metal surfaces
- Plastics
- Glass
- Ceramics
- Stone
- Concrete
Industrial Applications of Laser Cleaning Systems
Laser cleaning is preferred over traditional industrial cleaning methods in many different sectors. Some of the most common applications of laser cleaning are in these industries:
- Automotive
- Aerospace
- Medical
- Cultural and Heritage
- Electronics
- Glass and Optics
- Semiconductor
- Metal Fabrication
- Printing
Is Laser Cleaning Safe?
Yes, laser cleaning is an entirely safe process. However, it is crucial to use the laser cleaning system as intended. Laser cleaning follows a safety protocol that keeps human organs, such as the eyes, out of harm's way. Wearing eye protection when using laser cleaning is of prime importance.
Is Laser Cleaning Environmentally Friendly?
Yes, laser cleaning is a very environmentally friendly solution. Unlike traditional cleaning methods, laser cleaning does not rely on chemicals that harm the environment. Additionally, it adds to the recyclability and reusability of parts. This makes laser cleaning a green and sustainable solution.
Is Laser Cleaning Expensive?
No, laser cleaning is not at all expensive. In fact, it is one of the cost-effective ways of industrial cleaning. Laser cleaning uses no consumables, unlike traditional cleaning methods. Therefore, the operational cost of laser cleaning systems is negligible. The only important thing is the initial investment when buying the machine.
Essential Things to Consider When Buying or Using a Laser Cleaning Machine
Laser cleaning machines, like those provided by Allied Scientific Pro, are versatile in the materials and contaminants they can clean.
However, it is crucial to consider certain factors beforehand when choosing a laser cleaning system for a particular application:
- Laser Power: The main factor determining the amount of energy stored in a laser. The unit of laser power is Watts (W). A pulsed laser beam has short bursts of high energy. Therefore, the laser power for such beams is measured as an average. The peak energy in a pulsed laser beam can be a hundred times more than the rated laser power. Lasers usually come with multiple power settings.
- Fume Extraction: The fume extraction system should be used in conjunction with the incident laser beam. A sound fume-extraction system keeps vapor out of the laser's path.
- Pulse Duration: Longer pulses increase the exposure to the laser treatment. Too long a duration can damage the underlying material. A too-short duration can be insufficient to clean the material. Choose a duration value that can complete the job correctly.
- Scanning System: A scanning system can check the contaminated areas and automatically redirect the laser to clean them. This provides quick, fully automated laser cleaning.
- Type of Contaminants: Different contaminants have different ablation thresholds. Understand the contaminant you want to clean before using the laser pulse.
- Cost Effectiveness: Cleaning is generally a secondary finishing process for most industries. Ensure the budget you allocate to laser cleaners is a cost-effective solution for your industry.
- Reliable: The laser cleaning machine should be trustworthy to withstand the intended industrial use. Any breakdowns in the machine can cause supply chain disruptions and downtime.
Laser Cleaning vs. Traditional Cleaning Methods
To evaluate the efficacy of laser technology, it is important to compare it against other cleaning methods.
Laser Cleaning vs. Sand Blasting
Laser cleaning is significantly preferable over the sandblasting process. Sandblasting relies on a high volume of sand for its operation. Additionally, the process's ability is minimal. It is also harmful to the operator. However, laser systems have no such downsides.
Laser Cleaning vs. Chemical Cleaning
Chemical cleaning requires harmful chemicals that can damage the part. Additionally, chemicals are not environmentally friendly. The cost of using chemical consumables is also high. Laser systems provide a cost-effective and environmentally friendly alternative to chemical treatments.
Endnotes
Laser technology has significantly optimized industrial cleaning. The no-contact laser cleaning technology can remove contaminants at surprisingly fast speeds. If you are looking for a cleaning process for your workshop, the laser cleaning method is a perfect fit.
Take a look at our different Laser Cleaning Machines on our dedicated website.