Welding Using Fire Arc

Welding is the process of permanently joining two or more pieces of metal to make a part. This is an important industrial process, and has a strong impact on the U.S. economy. In fact, almost all the things we use every day or have been resolved or produced by the team that has been welded. This includes appliances, automobiles, buildings, bridges and other infrastructure. Welding is done through the application of heat or compression or both. Typically, heat is applied using a fire bow. This type is called a welding arc welding. Some people are confused with solder, which is a slightly different process. In the solder, the other ingredients melted in between parts to be fused. Welding arc, on the other hand, uses heat from the arc to thoroughly melt the metal pieces together.

Welding can also use a filler metal that melts into the seam of the pieces together. This is done either through the feeder cables in the trunk manual welding, or welding gun equipped with a wire feeder. In preparation for welding, the edges to be welded pieces formed into a groove, usually V-shaped groove Creating a pool of liquid flame arc from the edge of the grooved pieces of metal and filler metal. A shielding gas welding torches surround a pool of liquid. Shielding gas is required to prevent oxygenation and weakening of the welded pieces.

Generally metals including aluminum and steel welded. Plastics are also welded, but the heat source used was the heat or electrical resistor. Different industry groups hire different types of welders. In the construction industry, welders working on the construction of bridges and subways. Machine manufacturers employ welders to make the cranes and bulldozers, food processing equipment, printing machinery and other heavy equipment. The rent of land transport welder manufacturing industry and water-based vehicles, and aircraft. Welders also perform maintenance and repairs to car body shops and stores that specialize in the repair of industrial machinery. Welders are present in the petroleum industry, especially in the construction of oilrigs. In the electricity industry, welders needed in the construction of electric generators and equipment.

Penetration Welding

discussion concerning fastening 4130 chromoly steel on web forums and discussion boards. however apart from all the questions about pre-heating, filler metals, and conductor sort and size, Weld What concerning testing?
How does one recognize you're obtaining enough penetration in your welds. The short answer is-you cannot. you'll ne'er be completely positive you succeed the proper quantity on some weld penetration welds while not damaging the slicing and dicing and metallographic testing. however the nice news is that you simply is pretty darn positive.
By running the take a look at welds victimisation a similar actual material thickness and joint style, so by following the procedures that letter, you'll be pretty darn positive that you simply area unit sensible welds.

The following is the basic procedure to test the welds on the chromoly steel 4130:
- Determine the different weld configurations with which you need to test
- Prepare a weld joint with the exact same way as you would for production welds.
- Weld joint test and write down all the settings such as heat if used, the electrical current, electrode type and size, filler metal type and size etc.
- After the test welds and cool completely, specify multiple locations to examine the cross sections
- Part of the test welds using a slitting wheel.
- Poland weld test section ranging from 180 grit silicon carbide coarse, then 240 320, and finally 400 grit paper.
- Swap with acid and muriatic Q-tip as used in the pool (to follow all the recommendations listed on the MSDS for the safety of acid)
- Quickly rinse with baking soda and water solution to neutralize
- Check the welds using a 10x power
If the penetration is suitable, you currently have a fastening procedure for fastening 4130 chromoly is well-tried. If this procedure is followed and {also the} welds were also examined visually, you'll be pretty darn positive you've got adequate penetration and weld quality.

Laser Configuration

Laser Head

At the heart of the system is U.S. Laser's unique laser head. The laser head is based on a single lamp, single ellipse, close-coupled design, optimized for maximum pumping efficiency.  The design produces up to 700 watts with a small diameter (6.3 mm) rod.  The single lamp reduces consumable costs, while the high efficiency reduces the energy and cooling requirements as well.

The laser head design allows for easy cascading of heads, in a series periodic resonator.  Single and two-head systems are standard, and four-head systems are available.


An important feature of the design is that it is tunable: the output power can be smoothly varied from <20% to 100% of rated power without any anomalies in the beam characteristics.


U.S. Laser can also provide high brightness variants of the basic lasers, where the maximum power has been slightly reduced to significantly improve the beam quality. This is especially useful in laser cutting.



Power Supply -
 Cooling Console            

The electronics and cooling system, in standard systems, are housed in a caster-mounted console.  The closed loop cooling system features a proportioning valve controller to maintain constant head temperature, and a high efficiency heat exchanger for connection to external cooling water/chiller. 


The electronics include a high efficiency switching power supply, and a control unit with status monitoring and protection.  All of these lasers may be computer controlled via digital and analog inputs.  Optional IEEE 488/RS232/RS422 computer interfaces are available.



Optical Enclosure

The laser heads, in standard systems, are contained in an enclosure consisting of a tooling plate base and a hinged, interlocked cover.  An optional air filtration system provides a clean, positive pressure, environment for the optics, to protect against environmental dust.


       
Laser Beam Delivery  

U.S. Laser's High Power CW Lasers are available with both conventional and fiber optic beam delivery systems. Particular attention was paid to power handling and transmission capabilitiy to maximize power on target, and minimize optical element heating. All lens elements are fused silica, and are sized based on the full beam diameter or fiber numerical aperture.All surfaces are high damage resistant antireflection coated to provide minimum power loss.



Integrated Cabinet Systems 

Multiple headed systems are also available with an integrated cabinet. These systems fully enclose the laser head and optics, power supplies and cooler in a common environmentally sealed enclosure. The laser head and optics are mounted on a granite base to insure maximum stability, and the optics are water cooled. The interior of the cabinet is temperature stabilized for use in harsh factory environments. The laser and optics are easily accessible for service and alignment from the hinged cover assembly, while removable panels provide access to the rest of the system. Normally the system is controlled and monitored via an external control computer which is supplied by the customer. An optional touch screen control box is also available.


Work Area Enclosure                             

U.S. Laser offers a variety of standard and custom work area enclosures to complement the high power lasers.  CDRH Class I and Class IV enclosures are available.  The laser systems can also be easily integrated into existing CNC or robotic machines. U.S. Laser manufactures high power CW Nd YAG laser systems, equipment and machines for laser welding, laser cutting, cladding and heat treating applications
Standard laser enclosure shown with optional

Laser Welding

Laser welding of metals has significant advantages over traditional welding methods such as arc, TIG, and plasma welding processes. When weighing these advantages, consideration must be given to factors such as material composition, overall part size and configuration, manufacturing environment, weld quality & precision, processing time requirements, and processing cost requirements. Solid state lasers (such as Nd:YAG) are most often used for low to moderate power applications.

(Tech Note: U.S. Laser Corp 'Welding Article')
   

US Laser offers an assortment of both traditional Pulsed and Continuous-Wave (CW) lasers tailored for a variety of applications. Typically, Pulsed lasers are employed for Lap (penetration) welding requirements, whereas CW Lasers are used when Seam (Butt) welding is required. There are a few requirements in which a Q-switched laser may be applicable. However, review of individual customer requirement is recommended to ensure the proper laser is selected for the intended application.

In its simplest form, US Laser can provide a stand alone laser system for OEM applications. In this configuration, the laser head and associated optics are mounted on an optical rail, which is connected to a separate power supply / cooling cabinet by means of electrical cables and cooling lines. A beam delivery system (viewing and focusing module) can be incorporated as a means of directing the laser output to the work-piece. Fiber-optic beam delivery, conventional fixed beam delivery, and Galvanometer based (scanning) beam delivery systems are available depending upon the given application.

   

Lamp-Pumped Lasers

US Laser lamp-pumped Nd:YAG lasers employ the use of high-efficiency, long-life krypton arc-lamps to excite a solid-state Nd:YAG laser rod located within the laser cavity. The configuration of the cavity is optimized to provide high wall-plug efficiency and stable operation. Both fundamental TEM00 and multimode output modes are available. US Laser offers lamp-pumped lasers in single and multi-head configurations, with output powers ranging from several watts to 2400 watts average CW output power (link to US Laser CW systems) , up to 200 Watts average AO Q-switched output power, (link to US Laser QS systems) and up to 400 Watts average Pulsed output power. (link to US Laser Pulsed systems)

Diode-Pumped Lasers

Unlike their lamp pumped counterparts, Diode Pumped Lasers use high efficiency, long life solid state diodes as their pump source. Because of the excellent beam quality, US Laser Diode-Pumped Lasers can generally be focused to smaller spot sizes, and may be suitable for various low power welding applications. US Laser offers CW & AO Q-switched lasers in TEM 00 and multimode operation with output powers from several to 100 Watts, though higher laser output configurations are available as required on a custom basis. (link to US Laser Diode-Pumped systems)

Custom, Turnkey Laser Systems

US Laser offers custom, automated turnkey laser systems for laser welding applications. The 4000 Series Industrial Laser Systems are designed to perform demanding, precision laser processing tasks in a production environment. The Nd YAG Laser System combines accuracy and precision with stability and ruggedness for applications such as welding. (link to US Laser Machining systems) In addition, we offer several integrated cabinet laser systems which are designed for high output CW laser operation using fiber-optic beam delivery, and interfaced to a customer supplied PLC. link to US 408-2 and 408-4 CW systems)

Microprocessing

Structuring and ablation are closely related processes. Short laser pulses of extremely high power produce an energy density so high that the material practically vaporizes without passing through a liquid phase (it sublimates). Very little molten material results from this process. Each laser pulse produces a small depression that is typically 10, 20, or more micrometers in diameter and only a few micrometers deep.
Laser structured solar cell.

For a long time, very few people had ever heard of structuring and ablation with solid -state lasers. The rise in the popularity of microprocessing, however, has focused more attention on these processes. The reason for this is simple: both processes make it possible to machine workpieces in small and ultrasmall dimensions.

Structuring

produces uniformly arranged geometries in surfaces with the goal of inducing specific changes to the surface’s technical properties. In such structures, one single element often measures only a few micrometers.

Laser ablation

is usually used in the manufacture of tools and molds as well as in electronics and semiconductor technology. In injection molding, for example, lasers produce highly detailed, three -dimensional molds into which resin is injected for creating plastic parts. The laser, however, can also be used to trim resistors or mark parts by selectively removing thin layers of material.

Drilling

At percussion drilling multiple laser pulses "peck" at the workpiece, producing the hole little by little. Producing a pilot hole, that is then enlarged in a series of circular motions is called trepanning. Helical drilling means that many laser pulses work their way into the workpiece in a downward spiral.

Laser cutting and laser drilling

Laser cutting and laser drilling

The laser can handle a variety of cutting tasks.
These range from micrometer-precise cutting joints in paper-thin semiconductor chips to quality cuts in 30-millimeter-thick steel. In laser drilling, the laser beam generates very small to large holes in metals, plastics, paper and stone, without contact.
Principle of laser cutting.

Where the focused laser beam strikes the workpiece, it heats the material so extremely that it melts or even vaporizes. Once it has completely penetrated the workpiece, the cutting process can start: the laser beam moves along the part contour, melting the material as it goes. Usually, a stream of gas blows the melted material downwards, out of the cut. The gap is barely wider than the focused laser beam itself.

In laser drilling, a short laser pulse melts and vaporizes the material with a high power density.
The resulting high pressure drives the molten material out of the hole.

Laser welding and laser soldering

Laser welding and laser soldering

The laser beam provides a variety of ways to join metals: it can join workpieces at the surface or produce deep welds. It can be combined with conventional welding methods and, additionally, be used for soldering.
Laserschweißen von Dickblech.
Even when seam welding with continuous laser beams, the heat-affected zones and the complete heating of the component are still considerably less than with arc or plasma welding. The supply of energy can be well monitored, regulated and maintained or precisely controlled.

Materials with a high melting point as well as high heat conductivity can be welded using a laser. Due to the small amount of molten material and the short, controllable melting period, some materials can be combined, which otherwise could not be welded. Filler materials can be used, if needed. Even when seam welding with continuous laser beams, the heat-affected zones and the complete heating of the component are still considerably less than with arc or plasma welding. The supply of energy can be well monitored, regulated and maintained or precisely controlled.
In soldering, the mating parts are joined by a filler material, or solder. The surface of the solder seam is smooth and clean, forming a nicely curved transition to the workpiece. Since solder seams do not require finishing, they are often used in the automotive industry for making body parts such as trunk lids or car roofs.

Heat conduction welding

Heat conduction welding

In heat conduction welding, the laser beam melts the mating parts along a common joint. The molten materials flow together and solidify to form the weld.
In heat conduction welding, the surface is melted.

Heat conduction welding is used to join thin-wall parts. One example of this are corner welds on the visible surfaces of device housings. Other applications can be found in electronics. The laser produces a smooth, rounded seam that does not require any extra grinding or finishing. Pulsed or continuous wave solid-state lasers are used in such applications. In heat conduction welding, energy is coupled into the workpiece solely through heat conduction. For this reason, the weld depth ranges from only a few tenths of a millimeter to 1 millimeter. The heat conductivity of the material limits the maximum weld depth. The width of the weld is always greater than its depth. If the heat is not able to dissipate quickly enough, the processing temperature rises above the vaporization temperature. Metal vapor forms, the welding depth increases sharply, and the process turns into deep penetration welding.

Building shapes out of powder and wire

Building shapes out of powder and wire

Deposition welding is a generating process that is applied for surface finishing as well as repairing or modifying existing components. Depending on the task at hand, either manual or automated laser deposition welding is used.
Manual laser deposition welding: the laser beam melts the filler wire and deposits material on the workpiece surface.
Manual laser deposition welding: the laser beam melts the filler wire and deposits material on the workpiece surface.

Manual laser deposition welding

In the case of manual deposition welding, the welder guides the filler material "by hand" to the area to be welded. A thin wire with a diameter between 0.15 and 0.6 millimeters is primarily used as filler material in this process. The laser beam melts the wire. The molten material forms a strong bond with the substrate, which is also melted, and then solidifies, leaving behind a small raised area. The welder continues in this fashion, spot by spot, line by line, and layer by layer, until the desired shape is achieved. Argon shields the work process from the ambient air. Finally, the part is restored to its original shape by grinding, lathing, milling, EDM etc.
When coating the surface, several powder coatings are either melted onto one another or next to one another, as required. The individual welding paths must precisely overlap in order to achieve a texture that is free from errors.
When coating the surface, several powder coatings are either melted onto one another or next to one another, as required. The individual welding paths must precisely overlap in order to achieve a texture that is free from errors.

Automated laser deposition welding

In the case of automated deposition welding, the machine guides the filler material to the area to be welded. Although the material can also be a wire, this process primarily uses metal powders. Metal powder is applied in layers to a base material and fused to the base material and is fused to it without pores or cracks. The metal powder forms a high-tensile weld joint with the surface. After cooling, a metal layer develops that can be machined mechanically. A strength of this process is that it can be used to build up a number of similar or differing metal layers.

Highly productive processing with no downtime

Scanner welding – Highly productive processing with no downtime
Scanner welding today enables highly productive and flexible production line layouts, making welding in series production faster, more accurate, and thus more cost-effective than traditional welding processes.
The scanner principle.

In scanner welding, the beam guidance is done using mobile mirrors [1]. The beam is guided by changing the angles of the mirrors.[4]  A processing field [3] determine which weld can be carried out with the highest dynamics and precision. The processing speed and size of the focus diameter at the workpiece depends on the imaging properties of the optic, the beam incidence angle, the laser beam quality and the material.
 Using the method of an additional lens system [2], the focus point can also be offset extremely dynamically in the Z direction, in order to process three-dimensional components completely, without moving either the processing head or the part.

Due to the very fast translation movements, downtime is nearly eliminated, and the laser unit can produce during nearly 100% of the available fabrication time.
Scanner welding in action.

During welding, the scanner optics can also be guided over a workpiece in conjunction with a robot. This "flying" movement is what inspired the term "welding on the fly": the robot and the scanner optic synchronize their movements in real time. The use of a robot increases the workspace significantly, permitting true three-dimensional part processing.

To program a PFO, you can use a convenient editor which can construct and save welding figures on a workpiece.

High-power disk lasers with high beam quality are used as beam sources. One or more flexible fiber-optic laser cables lead the laser light from the laser unit to the processing station.

Deep penetration welding

Deep penetration welding

Deep penetration welding requires extremely high power densities of about 1 megawatt per square centimeter. In this process, the laser beam not only melts the metal, but also produces vapor.
Deep penetration welding produces a vapor-filled hole, or keyhole.


The dissipating vapor exerts pressure on the molten metal and partially displaces it. The material, meanwhile, continues to melt. The result is a deep, narrow, vapor-filled hole, or keyhole, which is surrounded by molten metal. As the laser beam advances along the weld joint, the keyhole moves with it through the workpiece. The molten metal flows around the keyhole and solidifies in its trail. This produces a deep, narrow weld with a uniform internal structure. The weld depth may be up to ten times greater than the weld width, reaching 25 millimeters. The laser beam is reflected multiple times on the walls of the keyhole. The molten material absorbs the laser beam almost completely, and the efficiency of the welding process rises. If CO2 lasers are used for welding, the vapor in the keyhole also absorbs laser light and is partially ionized. This results in the formation of plasma, which puts energy into the workpiece as well. As a result, deep penetration welding is distinguished by great efficiency and fast welding speeds. Thanks to the high speed, the heat-affected zone is small and distortion is minimal. This process is used in applications requiring deeper welds or where several layers of material have to be welded simultaneously.

Hybrid welding

Hybrid welding

By combining laser welding and one other welding process, special applications for steel construction can be achieved.
Automated laser welding between cruise ship decks.

Hybrid techniques refer to processes in which laser welding is combined with other welding methods. Compatible processes are MIG (metal inert gas) or MAG (metal active gas) welding as well as TIG (tungsten inert gas) or plasma welding.

Here’s an example that shows the advantages. In shipbuilding, large steel plates that can be up to 20 meters long and 15 millimeters thick are welded together. The gaps between the plates, however, are too large for the laser beam to bridge by itself. To get around this problem, laser welding is combined with MIG welding. The laser delivers the high power densities needed for the deep welds and enables high welding speeds. This, in turn, reduces heat input and distortion. The MIG torch, meanwhile, bridges the gap between the parts and closes the joint using filler wire. On the whole, the hybrid technique is faster than MIG welding alone, and the parts are subject to less distortion.

Laser hardening

Laser hardening

The advantages of laser hardening are less refinishing work and the ability to process irregular, three-dimensional workpieces. Costs related to refinishing work is reduced or eliminated entirely.
How laser hardening works: the laser beam heats the outer layer (case) of the metal. Rapid cooling causes the layer to harden.

Laser hardening is a surface hardening process. It is used exclusively on ferrous materials suitable for hardening including, steels and cast iron with a carbon content of more than 0.2 percent.

To harden the workpiece, the laser beam usually warms the outer layer to just under the melting temperature (about 900 to 1400 degrees Celsius). Once the desired temperature is reached, the laser beam starts moving. As the laser beam moves, it continuously warms the surface in the processing direction. The high temperature causes the iron atoms to change their position within the metal lattice (austenization). As soon as the laser beam moves away, the hot layer is cooled very rapidly by the surrounding material in a process known as self-quenching. Rapid cooling prevents the metal lattice from returning to its original structure, producing martensite. Martensite is a very hard metal structure. The transformation into martensite yields greater hardness.
This turbocharger shaft is laser-hardened in the sections where the bearings sit.

The laser beam hardens the outer layer, or case, of the workpiece. The hardening depth of the outer layer is typically from 0.1 to 1.5 millimeters. On some materials, it may be 2.5 millimeters or more. Greater hardening depth requires a larger volume of surrounding material to ensure that the heat dissipates quickly and the hardening zone cools rapidly enough.

Relatively low power densities are needed for hardening. At the same time, the hardening process involves treating extensive areas of the workpiece surface. That is why the laser beam is shaped so that it irradiates an area that is as large as possible. The irradiated area is usually rectangular. Scanning optics are also used in hardening. They are used to move a laser beam with a round focus back and forth very rapidly, creating a line on the workpiece with a power density that is virtually uniform. This method makes it possible to produce hardened tracks up to 60 millimeters wide.

Soldering

Soldering
The quality of the temperate by soldering is dependent upon the join partners.

In soldering, the mating parts are joined by a filler material, or solder. The melting temperature of the solder is lower than that of the component materials. As a result, only the solder is melted.

The mating parts are merely warmed. Once melted, the solder flows into the gap between the parts and bonds with the surface of the workpiece (diffusion bond). Soldering a joint requires access to only one side of the joint. The thin gap between the components functions like a capillary, drawing the liquid solder into the joint.
Laser soldering of a car trunk-lid (Picture: Photon AG, Berlin)


The soldered joint is only as strong as the solder material. In a related process called brazing, solders made of copper and zinc can produce joints that are as strong as those attained during welding. The surface of the solder seam is smooth and clean, forming a nicely curved transition to the workpiece. Since solder seams do not require finishing, they are often used in the automotive industry for making body parts such as trunk lids or car roofs. Before the parts are painted, they only have to be cleaned.

Other applications can be found in mixed constructions. Components made of dissimilar materials often cannot be welded or, if they can, only with limited success due to the very different melting points of the materials. Joining aluminum and steel is one such example. For these and similar joining tasks, soldering offers the perfect alternative.