All You Need To Know About Laser Welding Machines
In this article, you will understand what is laser welding? how does laser welder work? what are laser welders used for? how to use laser welding machine?
What Is Laser Welding?
Most laser welding techniques can be classified into two basic categories, “keyhole” and “conduction mode” welding. Both of these welding modes are capable of being performed autogenously, that is, without filler metal, as well as with filler, if so desired.
Keyhole, or deep penetration welding, is commonly encountered when welding thicker materials at high laser powers. In keyhole welding, the laser is focused so as to achieve a very high power density at the work piece. At the focus of the laser beam, the metal actually vaporizes, opening up a blind hole (the keyhole) within the molten metal pool. Vapor pressure holds back the surrounding molten metal and keeps this hole open during the process. The laser power is mainly absorbed at the vapor melt boundary and the keyhole walls. The focused laser beam and the keyhole continuously move along the welding path. At the front of the keyhole, new material is molten, and at the back, it resolidifies to become the welded joint.
The small size of the keyhole region results in a precise, narrow fusion zone, with a high aspect ratio (depth to width) as compared to arc welding methods. Furthermore, the highly localized application of heat means that bulk of the work piece acts as an effective heat sink so the weld region heats up and cools down rapidly. This minimizes the size of the heat affected zone, and reduces grain growth. Thus, the laser can generally produce stronger joints than arc welding, which is one of its primary benefits.
Laser welding also offers greater flexibility than arc welding, since it is compatible with an extremely broad range of materials, including carbon steel, high strength steel, stainless steel, titanium, aluminum, and precious metals. It can also be used to join dissimilar materials, as differences in material melting temperatures and heat conduction are of minor importance in the process.
In addition, laser welding delivers significant cost advantages over traditional methods, when all the process steps are considered. In particular, the precise application of heat minimizes distortion in the weld and overall part, thus eliminating the need for post processing in many cases. Plus, the ability to project the laser beam over relatively long distances with essentially no power loss makes it easy to integrate laser welding with other production processes, and lends itself well to integration with manufacturing robotics. Last, but not least, new product configurations with reduced flange sizes can be realized, which is critical for light weight vehicles in the automotive industry.
How Does Laser Welder Work?
A laser is a beam of concentrated light energy generated at a specific wavelength. In nature, light exists across a spectrum of wavelengths, ranging from very short (X-rays and gamma rays) to very long (radio waves). Humans can only see visible or the “white light” wavelengths from around 430–690 nanometers (nm). A laser beam is an amplified concentration of light energy at a specific wavelength. It is coherent light, which allows focusing on a tight spot and a narrow beam over long distances. The word LASER is an acronym that stands for Light Amplification by Stimulated Emission of Radiation.
Laser beams change when interacting with material
Laser energy absorption of a material varies based on a number of factors, such as wavelength, material thickness, crystalline structure, material additives, molecular structure, and more. The process takes the advantages of these material properties and laser to create a bond between two plastic materials: one that transmits the laser energy and one that absorbs it.
When a laser beam encounters any material such as plastic, it will either be transmitted, reflected, or absorbed based on the wavelength and the composition of the material it encounters. Most materials exhibit some degree of all three effects, but in varying proportions. A material may be optically clear to light in the visible spectrum and very absorptive to infrared laser, or be opaque to our eyes but transparent to infrared laser.
What Is Laser Welder Used For?
Laser welding can join materials that are not easily welded using other methods. Some of the materials that have been welded successfully to date include:
• Metals (steel, copper, brass, aluminum, silver, gold, alloy, and more)
• Acrylonitrile butadiene styrene (ABS)
• Acrylics
• Cyclic olefin copolymer
• Elastomers (TPU/TPE)
• Polyoxymethylene
• Polypropylene (PP)
• Polyphenylene sulfide (PPS)
• Polystyrene (PS)
• Thermoplastic polyurethane
• PBT
• Polyamide
• Polycarbonate (PC)
• Polymethyl methacrylate (PMMA)
• High-density polyethylene (HDPE)
• Low-density polyethylene (LDPE)
• Polysulphone
Laser welding is also effective with some dissimilar material combinations.
How To Use Laser Welding Machine?
General Steps for the Laser Welding Process:
1. Open the main panel door (unlock if necessary) and turn the key to the ON position.
2. Make sure to turn on the computer or tablet with the software/program attached.
3. Turn on the camera/TV for a second view (if applicable).
4. Turn on the protective gas by opening the valve (CCW) using the knob at the top.
5. Make sure the part or item that is going to be welded is positioned in a logical way that the laser welder head can reach. If it is a smaller part, keep it secure in a vice or another form of stability for the safety of the operator.
6. Turn on the fume extractor and make sure the vacuum is directed accordingly.
7. Now orientate the laser head to where it is roughly 8” away from the target weld surface.
8. Use the dials on the microscope to focus and magnify the clarity of the welding area.
9. Lock the laser head and base of the machine in place to ensure stability and accuracy.
The set-up is done and you are ready to laser weld.
10. Test the movement joystick with your none dominant hand (or however you’d like) to maneuver the laser welder head in the standard 3-axis direction. This will control the path that the laser beam itself will follow.
11. To activate the actual laser beam, you will use the foot pedal or whatever controller you have in your set-up. The foot pedal should be portable and you can place it wherever it is the most comfortable for your arrangement.
12. You will now take a piece of wire (they vary in size depending on the application) and hold it in your hand that is free or in other words, not the hand on the joystick. One way to hold the wire is as if you were holding a pen but place your thumb a little higher so you can distribute the force and create more stability over the wire material. However, with practice, you will find your most comfortable hand position.
13. Now combine steps 9, 10, and 11 to proceed to actually laser weld your specified area. Hold the wire steadily on the part in line with the area you are about to weld. Use the joystick to start at the tip of the wire and proceed to actuate the laser beam. Now follow the direction of the wire to melt the material together to create your laser weld.
