Welding – general information
Welding is a complex operation, as different types of welds are made with electrodes using specific techniques. Moreover, the level of expertise in the field and the type of metal are very important in the choice of the welding equipment and methods.
Welding is used in a variety of applications: industrial, with professional welding machines to join metallic materials or hobby for small crafts or even the creation of plastic or handicraft objects.
What is a weld
Welding is the fixed, solid joining of several pieces of different metallic materials by melting or pressure. You can think of it as a gluing made using special joining textures under certain physical or chemical conditions. It occurs by changing the physical state of the material.
Welding is used in the construction industries, as well as welding various decorative elements at home (e.g. fences, garden furniture, etc.).
What materials can be welded
Welding is mainly done on ferrous materials such as steel (sheet), cast iron or stainless steel. Other metallic materials such as aluminum, copper, brass, zinc, magnesium or titanium can also be used.
There are special plastic welding machines with the pertaining electrodes. These are mainly used in the car repair domain.
When welding, two materials are used: the base material (the one on which the “solder” is made) and the filler material (the molten material that strengthens the connection between the two pieces being welded). Welding can be carried out with or without filler material.
Types of welding
There are several ways to categorize the type of welding. Depending on the melting method, it can be flame or electric arc welding (with covered electrode or shielding gas).
They are also categorized in terms of the execution of the work, and you will find them as symbols. Thus bead welding is continuous, the while spot welding is intermittent.
Other perspectives to categorize the types of welding are in terms of process (melt or pressure) and sectional shape (U, Y, K, I etc.).
LASER or electron beam welding are two advanced, expensive methods used in specific industrial work.
Do you like to craft and want to learn how to weld, to make things in your backyard, to repair things or even to turn your hobby into a profession? It’s not a simple process, in fact you have to invest in the right welding machines for the metals and applications you want to realize, choose the right electrodes and safety protective equipment. Then it will be necessary to learn various welding techniques to achieve the right welding.
Equipment needed for welding
To perform a welding, you need a complete set of equipment, which also depends on the type of welding.
First of all, you need a welding machine or inverter that you choose depending on the application. Then you also need the welding mask, welding cable, table tongs, electrode tongs and, of course, electrodes.
The generator or welding machine
The welding machine is the basic component, the source that generates the power needed for welding and you can find various models and brands for each type of welding (SEI/ MMA, TIG/WIG, MIG-MAG). These are robust equipment, and the price range varies according to type, model and performance.
Conventional electrode welders are the cheapest (at the opposite pole are the weld inverter, but the price is reflected in the practicality of use), the disadvantage is the high-power consumption and the fact that you need experience to use it.
Welding machines can be further categorized into transformers, diode rectifiers, converters and welding generators.
Welding inverters are the latest generation of equipment, smaller, easier to handle and with low electricity consumption. Welding machines are cheaper than the welding inverters.
The welding cable
Welding cables make the connection between the electrode holder and the welding machine and are made of copper electrical wires of varying thicknesses, covered with an insulating material.
The type of cable you choose depends on the compatibility with the welding machine, its cross-sectional thickness and length. On the market you can find electric welding cables with connectors and rod holders.
The table cable
The table cable provides earthing, closing the electrical circuit between the welding machine (electrical power source) and the welded component.
The table cables are most often sold with pliers and electrode holders. These are chosen according to the thickness (diameter in cross-section), the electric current at which the pliers are designed to operate, the length of the cable and the size of the electrode holder.
Electrode plier
The purpose of the electrode holder pliers is to securely hold the electrode and ensure optimal electrical contact for welding.
Criteria for the choice of electrode holder are the current carrying capacity and size.
Table clamp
The table clamp is clamped to the workpiece to ensure the earthing. It is required for welding machines or inverters, whatever the technology (MMA, TIG, MIG-MAG).
The table clamp should be securely fixed to the component under work, according to the manufacturer’s recommendations.
The electrodes
The electrodes are metal wires, conductors of electric current, wrapped in a protective layer. They are classified according to the coating material, each coating influencing the welding characteristics, the slag layer released and the welding position.
Types of welding machines
Welding machines (inverters) are classified according to the technology used. The most popular welding machines are those with sheathed electrode and shielded gas welding machines.
Inert gas shielded welding machines – so called argon welding machines – are gaining ground (TIG or WIG, MIG-MAG) due to their finer execution and simpler use, even by the beginners. Different types of materials are used with gases of different concentrations.
Spot welding is one of the latest generation technologies, it is easy to use and finds an important use in the automotive workshops.
Electrode welding machines
The most known is the conventional method, the manual welding with a covered electrode (MMA).
Shielded electrode welders are useful for consistent welding, allowing the use from any position and working with any type of material. They are cheaper than gas-shielded versions and consistently more affordable than the inverters. The disadvantages are that they are more difficult to handle, have high electrode losses and require a certain level of skill.
TIG welding machines
The MIG-MAG machines are more modern, perform finer welds and can even be used by people with no experience. The disadvantage is that they are significantly more expensive than MMA.
TIG (tungsten inert gas)/ WIG (wolfram inert gas) arc welding consists of welding by heating the work area with an electric arc, while the filler material is placed separately by the operator. This type of welding is used for fine welds or for thin, thin materials with small thickness.
MIG – MAG welding machines
The MIG-MAG machines are more modern, perform finer welds and can even be used by people with no experience. The disadvantage is that they are considerably more expensive than MMA.
The MIG-MAG (metal inert gas – metal active gas) process is better known as argon welding. Although the welding principles are similar to the classical one, the procedure is improved because the molten metal is protected by an inert gas (argon), released together with the wire which is the filler material. The active gas is a mixture of argon and another gas (oxygen, carbon dioxide). By this means the worked materials are protected from oxidation.
Spot welding machines
The spot welder is one of the most modern equipment of its kind, being used for professional purposes in industries or locksmiths, but also for home projects (it is simple to use).
The welding is done, as the name says, by pressing in small spots. They are useful for welding aluminum, copper or sheet metal of various alloys.
Welding inverters
Welding inverters are the best devices of this type for both hobby and home crafts as well as for use in professional projects. They use a new technology, with a silicon plate replacing the bulky transformer.
This makes welding inverters compact, easy to use and does not require extensive welding knowledge. They are useful both for joining thick sheets and for fine work.
The disadvantage is the price, a cheap inverter costs about RON 400.
Types of electrodes
The electrodes are categorized according to the material from which the coating is made. Thus, there are electrodes with basic, acidic, rutile, cellulose or oxidizing coatings. The type of electrode also depends on the welding position.
Good welding electrodes must retain their quality over time and slag residues must be easy to remove.
Each type of electrode influences the type of weld. For example, acid-coated electrodes are made of oxides (iron, manganese, silicon) and help to weld in depth.
Rutile electrodes
Rutile electrodes have a protective layer made of rutile (titanium oxide) and ilmenite (TIFeO3). They leave a thin layer of slag, which is easily removable. They ensure an optimum arc with low losses.
The rutile electrodes allow welding from any position (vertical, horizontal, overhead).
Basic electrodes
Basic electrodes have a basic coating, e.g. carbonate or calcium chloride. They are useful for joining alloys or sheets with an increased carbon content.
Base-coated electrodes are used to make strong steel joints. Welds are resistant to high or low temperatures.
Cellulose electrodes
The cellulosic electrodes are covered with an organic material that releases gases that protect the metal bath during the execution. The advantage of this type of electrode is that it allows you to weld even from awkward positions. The disadvantage of cellulosic electrodes is the uneven weld bead.
Electrode sizing and average welding current
The electrode diameter influences the thickness of the weld metal and the intensity of the general electric current. The thicker the material, the thicker the electrode must be to allow more electric current to pass.
An average 2.5 mm electrode can withstand an electric current of 70 to 100 amperes, while a 5 mm rutile electrode can withstand a current of more than 200 amperes.
How welding is done
Having discovered the equipment and accessories, it’s time to find out how to weld MMA and beyond. There are working positions (represented by specific symbols), and the actual procedure involves certain steps.
Attention! Work with the welding machine should only be carried out with appropriate protective equipment.
Welding positions
The welding position is the way of working and applying the weld. It is represented by the angles that the electrode forms with the horizontal (the symbol is the alpha sign) or vertical (Beta), depending on the way the parts are joined together
There are several ways of joining the pieces, namely head-to-head, corner (outside/inside), cross, T, edge, edge-rounded, edge-rounded and overlapping.
There are several welding positions. These depend on the type of electrode and the operator’s access to the joined components.
The horizontal welding position
In the horizontal welding position, the angle between the horizontal and vertical axis (A) is 0 degrees (+/- 5 degrees), while the vertical versus horizontal angle is 0 degrees (+/- 10 degrees), so perpendicular to the work.
For corner welding, the vertical and horizontal working angle is 90 degrees.
Position in the welding ledge
At the horizontal position on the vertical wall in the cornice, the working angle from the vertical is 0 degrees (+/- 5 degrees) while the vertical to horizontal position is 90 degrees (+/- 20 degrees).
For corner welding the welding position is 0 degrees versus 135 degrees ( +/- 45 vs 20 degrees).
Weld ceiling position
The ceiling welding position is also called overhead because of the angle formed vertically of approximately 180 degrees (+/- 15 degrees) for head-to-head and corner work.
Vertical welding position
In the vertical plane position, the value of the angles is reversed from the horizontal plane, and the values are maintained for both head-to-head and corner work. There are two types of positions: up-facing/ascending and down-facing/descending.
The alpha (horizontal) angle is 90 degrees, while the vertical axis angle is between 0 and 180 degrees.
Stages for welding
Preparing the welding machine is important for your safety. Specifically:
– Install the welding cable, ground cable, ground clamp and, if applicable, the electrode holder. Most modern welding machines and inverters can be supplied with all cables fitted.
– Mount the electrode making sure it is connected to the current polarity.
– Put on your clothes and welding mask.
– Apply welding methods specific to the material and purpose of the joint.
– Check the strength of the work
Preparing materials for welding Down
Before you get to work we recommend that you make a number of checks:
– Check the integrity of the cables (welding, supply, earthing).
– The electrodes must not be moist.
– In the case of argon welders (WIG type), the electrodes must be sharp.
– Make sure that you can supply the welder with a suitable voltage source (230V/ 400V).
– Depending on the welding machine and type of electrode, the surface of the welded objects may require certain features.
– Make sure you have the complete welding equipment.
Welding equipment installation
The welding equipment must be prepared for work, observing all safety measures. We recommend you follow these points:
– The welder machine is a live working equipment, so make sure that the welder is fitted with a cable more than 6 mm. thick.
– Stretch the power cord so it has no loops or knots.
– Choose only working length cables less than 100m.
– Check the polarity of the connections.
– Equip yourself with special protective equipment before welding.
Follow the manufacturer’s instructions before starting the assembly routine.
Installing and connecting welding consumables
The welding equipment must be prepared for work, observing all safety measures. We recommend you follow these points:
– The earthing cable with a diameter larger than 6 mm should be attached according to the manufacturer’s recommendations. Make sure you opt for the right thickness of the welding cable (long cables decrease the performance of the machine or inverter whether it is MMA, TIG or MIG- MAG. A thick cable protects you from voltage drops).
– Check whether you have complied with the polarity of the connections.
– Follow the installation steps of the welding machine or inverter according to the manufacturer’s recommendations. Pay attention to how the polarity of the cables is connected, since equipment powered by direct current (DC) can be connected directly (positive polarity, connect the workpiece to +, electrode pliers to – ) or the other way around (connect the object to the – terminal, pliers to + ).
– Adjust the current intensity according to the electrode diameter.
The welding itself
After fitting the cables, pliers and electrodes, it’s time to find out how to weld properly. Here are some brief tips on the specifics of each type of material.
How to weld with argon?
Argon welding is performed with TIG/ WIG machines or inverters, and for these we give you some specific tips:
– Sharpen the electrode according to the recommendations in the user manual.
– Mount the electrode. The most comfortable working angle is at an inclination of 15-20 degrees.
– Choose electrodes recommended for the material you are welding.
– The welding technique depends on the material and its thickness.
How to weld aluminum?
When welding aluminum with argon welding machines (TIG/ WIG), after sharpening the electrode, polish the tip until it becomes flat.
The travel speed for aluminum is higher than other metals. Thus, our advice is to check the working speed versus the thickness of the aluminum sheet. When welding, maintain a constant angle of thrust. If you are new to welding, reconsider welding aluminum sheets thinner than 8 mm.
How to weld stainless steel?
In the case of stainless steel one problem that occurs during argon (TIG) welding is deformation, and this arises from too high an intensity or prolonged application of heat in the same place. You can tell this from the rusty-gray appearance of the material being processed (the color should be salmon-orange).
All you need to do is to decrease the current intensity (or reduce the electrode size) and increase the working speed.
How to weld galvanized pipe?
Some of the problems that occur when working with galvanized pipes are oxidation, blackening of the top layer and the porous appearance of the weld. To reduce this problem, polish the galvanized surfaces to be welded.
How to weld copper?
Copper is a soft metal with a low melting temperature, so it is difficult to work. Copper is welded with direct current, reverse polarity. Some experts recommend helium as a better option instead of argon (it amplifies the current intensity).
When welding copper it is not recommended to insist on a single point for a long time because it oxidizes quickly. So, you need a fast and constant travel speed over the material being worked.
How is cast iron welded?
Due to its high carbon composition (10 times that of steel), the biggest challenge is not cracking the weld. The temperature that cast iron withstands is 788 degrees Celsius, and if it exceeds this level the material can crack while working.
There are two ways of working to prevent these problems: preheating or without heating the cast iron. Specifically, the entire cast iron object is heated to a comfortable level above the critical point (about 650 degrees Celsius heating). Even in the case of welding without preheating it is useful to increase the temperature to about 40 degrees Celsius.
Cleaning welding slag
Welding slag occurs especially when welding with conventional manual welding machines with a covered electrode (MMA). After welding, the seam is beaten to remove the slag.
If you need to apply a new layer of weld, we recommend sanding the weld bead.
Checking the resistance of the weld
The weld can be checked visually by observing porosity. Another way of inspection is to use liquid or magnetic powder to see how it penetrates or how it is attracted (if there are holes/porosities). Ultrasonic machines can tell you the safety of the weld without affecting the work.
A simple but less constructive way is to tear a piece of weld and see how it looks, how even it is.
Protective welding equipment
As we have said before, any welding operation must start with the equipment. Make sure you have the proper equipment consisting of a mask, pants, apron and special gloves.
Welding mask
The eyes are the most exposed during welding. Choose a quality mask that is lightweight, provides the necessary darkness and is resistant to shocks and high temperatures. For comfort, choose a mask with a stable, lightweight, stable fit.
In our online shop you can find cheap welding masks as well as some very advanced ones, all providing the necessary protection. A liquid crystal mask costs around RON 120.
Welding pants and protective apron
The sweatpants are durable and made entirely of flame repellent material. As this is a milling outfit, choose to have as many pockets as possible.
The welder’s apron is made mainly from cowhide leather and sewn with flame-repellent thread.
Protective welding footwear
The quality welder’s boots are made of cowhide leather and are fitted with a safety flap.
The soles are made of anti-static and non-slip material.
Protective welding gloves
Welder’s gloves are made of spalt or cowhide leather, resistant to cutting and puncture. The sleeves are long and cover your wrist.
They are sewn with flame repellent (Kevlar) thread. The quality cuffs are made of cowhide, have an abrasion layer in the palm and adjustable cuffs.
Welding protection rules
– First and foremost, keep children away from the welding torch.
– Make sure the earthing is done correctly.
– Check the insulation of cables.
– Do not touch electrical parts or the electrode without gloves or wearing wet clothes.
– Only weld in a stable position.
Tips for successful welding
The choice of equipment, the model of the machine, the appropriate welding techniques, the way you keep the electrodes are all elements that contribute to the desired result, namely a smooth welded bead and, above all, a strong joint.
If you’re a beginner, you can start practicing on sample materials and then move on to your work. We want this material to be a complete tutorial on electric welding, so here are some final tips.
Checking the power supply
This is an important aspect, which is why we insist on it. Before getting down to work, check all the aspects related to the power supply and connection of the welding machine or inverter, such as:
– supply voltage (230 V vs 400 V);
– the length of the power cable (a long cable can lead to voltage drops);
– the thickness of the earthing cable.
Practice welding on sample materials
If you are a beginner welder or if you are welding new materials or materials of different thicknesses that you have never worked with before, our recommendation is to do a test on a sample of the same type of metal.
This way you can inspect the quality of the weld and then choose the right electrode and electric current.
Zigzag electrode movement
If you’re a beginner, here’s another tip to help you weld correctly and easily. When you have to weld two materials at an inside angle, weld in a zigzag pattern, in dots, in equal steps.
This is a tip that we give you and that you will probably also find on welder forums.
Keeping and storing the electrodes correctly
Poor quality electrodes affect the quality of the weld (slag, oxidize). Keep electrodes away from moisture.
This is especially true when welding with a manual electrode or MMA inverter. The humidity also damages the wolfram electrodes.
Equipment needed for welding
To perform a welding, you need a complete set of equipment, which also depends on the type of welding.
First of all, you need a welding machine or inverter that you choose depending on the application. Then you also need the welding mask, welding cable, table tongs, electrode tongs and, of course, electrodes.
The generator or welding machine
The welding machine is the basic component, the source that generates the power needed for welding and you can find various models and brands for each type of welding (SEI/ MMA, TIG/WIG, MIG-MAG). These are robust equipment, and the price range varies according to type, model and performance.
Conventional electrode welders are the cheapest (at the opposite pole are inverter welders, but the price is reflected in the practicality of use), the disadvantage is the high-power consumption and the fact that you need experience to use it.
Welding machines can be further categorized into transformers, diode rectifiers, converters and welding generators.
Welding inverters are the latest generation of equipment, smaller, easier to handle and with low electricity consumption. Welding machines are cheaper than welding inverters.
The welding cable
Welding cables make the connection between the electrode holder and the welding machine and are made of copper electrical wires of varying thicknesses, covered with an insulating material.
The type of cable you choose depends on the compatibility with the welding machine, its cross-sectional thickness and length. On the market you can find electric welding cables with connectors and rod holders.
The table cable
The table cable provides earthing, closing the electrical circuit between the welding machine (electrical power source) and the welded component.
The table cables are most often sold with pliers and electrode holders. These are chosen according to the thickness (diameter in cross-section), the electric current at which the pliers are designed to operate, the length of the cable and the size of the electrode holder.
Electrode plier
The purpose of the electrode holder pliers is to securely hold the electrode and ensure optimal electrical contact for welding.
Criteria for the choice of electrode holder are the current carrying capacity and size.
Table clamp
The table clamp is clamped to the workpiece to ensure the earthing. It is required for welding machines or inverters, whatever the technology (MMA, TIG, MIG-MAG).
The table clamp should be securely fixed to the component under work, according to the manufacturer’s recommendations.
The electrodes
The electrodes are metal wires, conductors of electric current, wrapped in a protective layer. They are classified according to the coating material, each coating influencing the welding characteristics, the slag layer released and the welding position.
