[tintuc]Welding Electrodes are the essential components in the process of welding. We use welding to join different materials permanently. In simpler words, welding electrodes are cylindrical shaped metallic rods, coated with flux and comes in varying lengths and radius.

These rods help in making a bead of metal by using electrical currents (AC/DC) from the welding machine. The welding electrodes are classified with the class well imprinted in its body, through which we can judge the electrode coating, its penetration capability and type of current it uses.

Technically the welding electrode is made up of two parts; first is the actual metal which is formed into wires and cut into specified length and second is the flux coating where begins the chemistry role.

The metal used in the welding rod may vary from mild steel, cast iron, stainless steel, copper, brass or aluminum. The flux wrapped on these metal rods is cellulose used by plants for flexibility, powered iron, and hydrogen. Sodium and potassium are also used to make the flux and works as a binding agent. The flux coating on the metallic rod helps the electric current to flow more evenly during welding.

Metallic Wire

The role of metallic wire is bought from the supplier with low carbon and silicon contents in it. These wires are inspected in the composition and can be heat treated if required to increase the ductility property of the metal.

Metal Forming

This metal forming process is used to reduce the cross-section of the wire by pulling it through drawing dies. These metallic wires are then drawn in the metal forming machines, where they are shaped into special sizes as per the requirement. The common sizes of these metallic rods are mainly 2.5mm, 3.15mm, 4mm, and 5mm.

Straightening and Cutting

After the metal forming process is completed, the feed is provided to the straightening and cutting machine. Here the metallic rod is straightened and cutting is done as per the specified length of the welding electrode.

Watch video below to understand making of welding electrodes better

Dry Mixture

The dry mixture is the chemical composition of the flux to be coated on the metallic rod. The chemical mixture mainly consists of Cellulose, Mica, Titanium Dioxide, Low Carbon Ferro Manganese, Feldspar etc. These elements are weighed well before preparation and added to the dry mixer to make a homogenous mixture out of it.

Wet Mixture

Potassium Silicate is weighed and added to the dry mixture to obtain a wet mix out of it. This basically acts as a binding agent for the mixture. Now the wet mixture is collected and loaded into a hydraulically operated press, where it is pressed to form briquettes. These briquettes are further loaded in the flux cylinder of the extruder.

Coating the flux by extrusion

The coating of the flux on the metallic rod is done by the extrusion press. Here the flux is fed under pressure through a cylinder and the wire is fed from the wire magazine. During the extrusion process, the metallic wire is fed one by one from the wire feeder and is well coated with the flux by the help of nozzle or die box mechanism well incorporated in the extrusion press. The metallic rods coated with flux are regularly tested in an eccentricity tester to confirm the right formation of the welding rod.

The rods rejected during the test are collected and the flux is stripped off in the stripping rod. These metallic rods can be reused in the process again. The electrodes coming out of the press with the help of conveyor are brushed to make the surface smoother and one end of the welding rod is well ground which is used for holding it by the holder during welding. Then these welding rods are collected in the tray for air drying and after some time they are fed in the oven for proper drying.

Baking of the electrode

After the collection of welding electrodes in the tray, they are fed in the oven for baking. The baking period varies with the size of the electrode and this is basically done to reduce moisture content. It is advisable that the moisture content should not exceed 4 percent for the proper functioning of the welding electrode.

Grading and Packing

When the baking cycle is over the grading of the welding electrode is done by printing the type of electrode on its body. Then, at last, the finished welding electrodes are stored and packed in the specific cartoon.

Welding Electrode Classification

Welding electrodes come in variable sizes and applications. They are judged by the grading done on its body. For example, the most commonly used electrodes are E6010 and E7018. Here E stands for Electrode and 60, 70 specify the tensile strength of the rod. The last two digits help in specifying the type of coating, current and welding positions like overhead, vertical, horizontal and flat.

Source: Technology Insider

[/tintuc]

[tintuc]

 WELDING DEFINITION — WHAT IS WELDING?

During the welding process, a welder or machine joins two pieces of metal using heat or pressure. In soldering or brazing, the two pieces stay separate but joined. Meanwhile, welding connects the metal to form a single piece. Welding involves two types of materials:

• Parent material: A weld’s parent material includes the metal parts that join during the process.
• Fillers or consumables: During the welding process, added materials called fillers or consumables can help form the final piece.

A weld can count as homogeneous or heterogeneous. In a homogeneous weld, the consumable has a similar composition to the parent material. Heterogeneous welds involve filler materials that have a different composition than the parent material.

HOW DOES WELDING WORK?

The welding process involves a variety of approaches and joint types. Techniques for welding can fall into one of two broad categories:

• Fusion welding: As the most commonly known form of welding, fusion welding uses extreme heat to join metal pieces. The welder can use an inert gas or filler metal to strengthen the bond.
• Pressure welding: During the pressure welding process, the welder applies external pressure to the two pieces. Pressure welding can happen at a temperature below the material’s melting point in a process known as solid state welding.

Welders use fusion welding in a wide range of applications for many industries. Pressure welding techniques tend to involve specialized methods that suit more niche applications. Types of joints formed in welding include:

• Butt joint: 135-180° angle connection between two ends
• Lap joint: 0-5° angle connection between two overlapping parts
• T joint: 5-90° angle connection between one part’s edge and the other’s face
• Corner joint: 30-135° connection between two ends or edges
• Edge joint: 0-30° degree connection between two edges

Since welding involves multiple techniques and connections, it’s used in numerous applications.

TYPES OF WELDING PROCESSES

Both humans and machines can perform the process thanks to developments in welding technology. Learn more about each welding technique:

Manual welding: In manual welding, a trained welder uses specialized equipment to join pieces of metal. Welding professionals understand their industry’s best practices for creating high-quality parts and products.

Robotic welding: Automated welding processes involve robotic welding tools that can weld metal to a project’s specifications. Robotic welding can achieve precise, high-quality results at a high level of efficiency.

Many metal fabricators utilize both robotic welding automation techniques and manual welding by humans for the highest level of control.

[/tintuc]

[tintuc]

Modern metal fabrication would be impossible without welding, but where did this technology originate? Who discovered it, and what can we observe about how it has changed over the years? Here are the answers to some of your most pressing questions about one of the most significant developments in metal fabrication.

WHEN DID WELDING ORIGINATE?

As you might imagine, welding has been around for quite some time. We can assume it existed in some form as far back as the Iron Age and the Bronze Age. There is evidence that the Egyptians learned to weld iron together, and we have found small gold boxes with pressure-welded lap joints from over 2,000 years ago.

However, the type of welding prevalent then and during the Middle Ages was a very rudimentary type of welding that typically involved hammering two pieces of metal together under heat until they joined. Conventional welding as we know it did not appear until the 19th century.

WHO INVENTED WELDING?

No single person takes credit for the invention of welding. Some of the earliest inroads toward traditional welding came about as early as 1800. In that year, Sir Humphry Davy produced the first electric arc between two carbon electrodes through the use of a battery. In 1836, Edmund Davy discovered acetylene. But the process we recognize as welding today didn’t arise until 1881.

It started with Auguste de Méritens, who used arc heat to join lead plates together. His Russian student, Nikolai Benardos, then patented a method of electric arc welding with carbon rods. After that, welding processes advanced rapidly. Nikolai Slavynov figured out how to use metal electrodes for welding. Following this, C.L. Coffin, an American engineer, discovered an arc welding process using a coated metal electrode that became the precursor of shielded metal arc welding.

HISTORY OF WELDING TIMELINE

Welding history is a rich study of human ingenuity and spirit. After its invention, welding continued to evolve, bringing it to its modern-day form. Ancient welding looks a lot different than it does now. But each step in the welding timeline is an impressive leap of mechanical engineering. Here are some of the pivotal moments in welding history.

• 4000 BCE: Historians believe the ancient Egyptians developed the earliest forms of welding around this time. Civilizations started welding with copper, and over time, moved on to other metals like iron, bronze, gold and silver.
• 3000 BCE: The Egyptians used charcoal to generate heat to turn iron ore into a loose substance called “sponge iron.” They then hammered the loose particles together to join pieces in the first instance of pressure welding.
• 1330 BCE: The Egyptians began soldering and blowing pipe, joining pieces of metal together.
• 60 CE: The historianPliny recorded information about the gold brazing process. He included information about using salt as flux and even mentioned how a metal’s color reveals its brazing difficulty.
• 310 CE: Indian welders created the Iron Pillar of Delhi, which still stands today, using iron from meteorites. The Pillar remains an impressive display of early craftsmanship, at 25 feet high and six tons in weight.
• 1375 CE: Forge welding was at the forefront during this period. Blacksmiths would heat metal pieces and pound them together until they bonded.
• The 16th century: Welders advanced in their craft during this period. Manuscripts from this century included the first references to the word “weld.” The Italian goldsmith Benvenuto Cellini wrote about a soldering process used for brazing silver and copper.
• The 18th century: Welding technology skyrocketed in the 18th century due to the Industrial Revolution, which paved the way for the society we know today. Industries needed more advanced welding practices to achieve their goals. Welders developed innovative welding technologies to meet this demand. A couple of new advances included the development of blast furnaces and the discovery of oxygen.
• The 19th century: This century saw the discovery of the electric arc by Sir Humphry Davy. Other inventors also innovated and patented fusion welding, bare metal electrode welding and carbon arc welding. Robbers used a torch to break into a bank vault, providing the first look at purposely using torches to melt metal.
• The 20th century: Thermite welding first emerged in 1903. In 1919, C.J. Holslag invented alternating current welding, replacing electric arc welding as the most prevalent form of welding in the United States. Welding continued to increase and was in high demand due to the First and Second World Wars. President Woodrow Wilson established the United States Wartime Welding Committee to increase the production of welded equipment.

HOW HAS MODERN WELDING CHANGED?

Since the 19th century, people have developed increasingly efficient techniques for accurate, fast and effective welding. Today, we even have robotic welding, a method growing in popularity that uses computer control to weld metal much more quickly and accurately than is possible through manual welding. It also significantly reduces or eliminates any risks to human workers. We can only imagine what incredible new welding processes the 21st century will bring.

[/tintuc]

[tintuc]

Working with thinner sheets of metal is tricky. If you use too much heat, you may end up with a burn through. Too little may result in not enough weld penetration and will produce brittle joints.
The welding process you choose plays a critical role in the success of the procedure. If you want to know how to weld thin metal, then keep on reading.

To ensure a successful joint when working with thin gauge material, you need to keep a few things in mind.

Minimizing Burn Through

A burn through occurs when the molten weld pool collapses, dismembering itself from the workpiece. The result is a large hole instead of a perfect joint. The defect arises due to high-temperature inputs and is impossible to workaround. The welder will then have to start again on a new workpiece.

Weld Bead Appearance

Because thin-gauge metals warrant the use of lower heat inputs, the weld bead appearance may produce a higher amount of spatter. Welders usually face this problem when working with stainless steel filler metals.

Torch Angle

The placement of the torch significantly impacts the amount of energy transfer. You need to take into account the properties of the metal and its melting point when deciding on the working angle and travel speed. All these factors impact the amount of energy the metal is exposed to at one time. It can either increase or reduce the risk of a burn-through.

Shield Gas

Your choice of gas significantly affects the productivity rate of the process. If it does not transfer energy as effectively as it should, it could produce weak quality joints. If it has incredibly high energy transfer rates, it will create a significant amount of spatter, and you also run the risk of blowing through the material.

You can use either the tungsten Inert Gas (TIG) or Metal Inert Gas (MIG) welding procedure for these types of joints.

Metal Inert Gas for Thin Sheets

Gas Metal Arc or Metal Inert Gas welding is the most commonly used welding procedure for metal sheets. Depending upon the weld type and the size of the sheet, you can use either the regular MIG welding technique or combine it with the pulsing method to avoid a blow through.

Pulsing

In this method, you heat a small segment of the plates that are to be joined and then allow the weld pool to cool completely. You should not attempt to fill in the join all at once as it can create a hole in the workpiece instead.

The process has high material penetration and metal deposition rates. The intense energy exposure in this technique warrants extra care when working with brittle material. To control the amount of risk, always use the shortest wire diameter in the process. It takes less energy to melt, which limits the amount of heat transfer to the base metal.

A significant reason why this method is so widely employed when working with sheet materials is the control it allows over the energy input. It also allows for better control over the weld bead appearance, which makes it easier to fix mistakes that may arise due to lower deposition rates.

[/tintuc]

[tintuc]

Welding is the process of joining materials together by melting the two pieces and adding a third melted material. Electrodes provide a current to the materials and are made of a variety of difference materials. Electrodes are manufactured for different purposes and welding types and are classified by a five-digit number like E7011-M. Each number and letter corresponds with a piece of information, including recommended welding position, tensile strength and penetration depth. The "E" in the classification stands for electrode.

Strength

The first two digits of an electrode classification indicate the strength of the electrode. This strength is measured in thousands of pounds per square inch (psi). For example, an electrode classified as E80xx has a tensile strength of 80,000 psi. This number also determines the yield strength or point of deformation for low alloy steel electrodes. Subtract 13,000 from the electrode tensile strength to determine the approximate minimum yield strength. For example, the E80xx electrode has yield strength of 63,000 psi.

Welding Position

The third digit of the electrode classification determines the appropriate welding positions. Welds are performed in four major positions: flat, horizontal, vertical and overhead. Exx1x electrodes can be welded using all four positions with the vertical position moving up. Exx2x electrodes use only flat and horizontal positioning. Exx4x electrodes may use all positions with the vertical position moving down.

Classification Type

The fourth digit represents the classification type. The classification type states the electrode’s coating, penetration depth and required current type. Penetration depths range includes light, medium or deep. Current types include alternating current (AC), direct current electrode positive (DCEP) and direct current electrode negative (DCEN), though some electrodes use multiple types depending on the type of weld. For example, an Exxx7 electrode is coated with iron powder and iron oxide, has a penetration depth of medium and uses AC or DCEN power.

Additional Requirements

Certain electrode classifications include a suffix which identifies any additional requirements or information. Low alloy steel coated electrode requirements differ from the requirements of mild steel coated electrodes. Some common suffixes include M, which signifies military-grade electrodes, and G, which signifies that the electrode has no required chemistry.

[/tintuc]