Welding process: How do I weld?

Welding - welding equipment and welding processes in overview

Welding process: How do I weld?: welding

By definition, welding is a joining process in which - with the addition of heat and / or pressure and optionally with the addition of an additive - materials are permanently bonded. In short, it can also be said that materials are melted, connected and cooled down again. Although welding is often associated with metals, it is also referred to as the thermal bonding of plastics as a welding process.

Decisive for the term "welding" is the achievement of the liquidus temperature (transition to the liquid state) of the materials to be joined. Only in this way is a cohesive connection achieved, whereas in hard and soft soldering only the additive is liquefied and adheres to the contact surface to be connected. Here no cohesive connection takes place.

Subdivision of welding processes

Depending on how the melting temperature is reached and which filler metals are used, the welding is divided into fusion welding and pressure welding.

A distinction is made between welding in the form of how the liquidus temperature is reached and which additives and auxiliaries are used in the welding process.

Since thatpressure welding is used only in industrial production, the various methods are only to be mentioned here:

Welding process: How do I weld?: weld

Fire welding - a form of pressure welding
  • forge welding
  • resistance welding
  • Cold pressure welding
  • friction welding
  • ultrasonic welding
  • explosive welding
  • Electromagnetic pulse welding
  • diffusion welding

Thefusion welding in its different variants, however, is used in industrial production and partly also in the private workshop. Here, the required temperature is not reached by pressure or friction, but by a heat source. This can be done by a gas flame or by an electric arc, which reduces the technical complexity compared to the pressure welding.

Welding process: How do I weld?: welding

Aluminum thermal welding of rails
  • Gießschmelzschweißen
  • Gas fusion welding (autogenous)
  • beam welding
  • Resistance fusion welding
  • Aluminum thermal welding
  • Arc-weld
    • Manual arc welding
    • Submerged arc welding
    • Inert gas welding (MIG, MAG, TIG)
    • plasma welding

Welding and welding machines for do-it-yourselfers

Many of the mentioned types of welding are unsuitable for the domestic workshop, as they are intended only for special applications and therefore are not profitable. Gas arc welding (autogenous welding) is the main choice, as well as manual arc welding and gas-shielded arc welding (MIG, MAG and TIG) from the group of arc welding processes. We would like to introduce these welding processes in more detail and explain the function of the welding machine.

Gas fusion welding - autogenous welding

Welding process: How do I weld?: process

Gas welding requires a manageable accessory.

As the name implies, in gas fusion welding, the material to be joined is melted with a gas flame and welded. In most cases, a filler material is introduced in the form of a welding wire. This ensures that sufficient material is available to achieve a secure connection of the weld.

The term "autogenous welding" or "autogenous welding" is derived from autogenous = self-employed, since for the production of the weld only a hot flame (if necessary welding wire) and no further aids are needed. The burning of the fuel gas requires oxygen, which is fed but also removed from the environment. Without excess oxygen around the molten bath and the fresh weld, there is no danger of the fresh weld oxidizing. This process and the independence of other excipients for oxidation protection, make gas welding independent or autogenous.

The advantage of gas welding is above all in the easily metered heating of the workpiece, so that it is frequently used in sheet metal processing and in bodywork applications. Here can "welded with feeling" and holes can be closed in the sheet metal. Nevertheless, it is also possible to use the welder - by changing the flame setting - to separate steel sheets.

The welding process distinguishes between two variants of the welding direction:

  • Rightward welding: The welding process is viewed from the perspective of a right-angled handler, which holds the torch with the right hand and holds the welding wire in the left hand. If the welding process is carried out from left to right, the flame of the burner is directed to the already created weld, keeping it hot for a very long time and the melt can run deep into the root. The flame direction additionally prevents oxidation of the weld seam. Qualitatively results in a very good and secure weld, so that right-justified welding is mainly used for thicker sheets. With thinner ones, there is a risk that the melt will run through the sheet and holes will be formed.
  • Leftward welding: With the same handling but a burner guide from right to left, the flame no longer protects the weld, which can lead to oxidation. A large part of the heat generated slides over the prepared weld joint and no such good weld root can be produced. Advantageous, however, is the moderate heating and faster cooling, with the very thin sheets can be welded.

Welding process: How do I weld?: process

Right-Right Welding - Weld (left) can flow for a long time

Welding process: How do I weld?: process

Nachlinks welding - weld (right) cools quickly

Manual Arc Welding - Do-It-Yourself Welding Technique

The manual arc welding - arc welding, electric welding or electrode welding - was displaced in the production for the most part by inert gas welding. The welding process is too slow and the quality of the weld strongly depends on the skills of the welder. However, electrode welding offers many advantages, making it predestined for use on construction sites, outdoors or in private workshops.

Welding process: How do I weld?: weld

Electrode welder for DIY enthusiasts from 50 euros available
  • low in purchase
  • usable by different electrodes for many materials
  • Welding possible in every situation
  • welding under water possible
  • very flexible
  • a long electrode allows welding in the narrowest areas

Electrode welders are available in many different sizes and simple devices are already under € 100 to get. Apart from a power connection and suitable electrodes, no further welding technique is needed. This makes the electrode welder a welder for home improvement. There is no need to store gas bottles and even a 230 V connection is enough for small welding jobs.

However, electrode welding requires some practice, experience, and a steady hand that feeds the electrode evenly during the welding process. With different electrodes even almost all metals and even cast iron can be welded.

How does electrode welding (manual arc welding) work?

Like other "electrical" types of welding, electrode welding requires grounding at theWorkpiece (5) and a high voltage at the contact of theElectrode (1) reaches a high temperature with the workpiece. The high temperature ensures that theMetal core of the electrode (2) and also the edge of the weld toMolten bath (4) liquefy and connect with each other. To inclusions and corrosion of new Weld seam (6) To avoid the electrode has a coat of various additives that positively influence the welding process by stabilizing the arc, metallurgically improve the weld and form slag, as well as a protective gas. While thatProtective gas (3) preventing oxidation of the molten bath, surrounds the resultingSlag (7) the new weld, "protects" it and provides a slower cooling. After the welding process, the slag can be easily knocked off

Welding process: How do I weld?: process

Good guidance of the electrode is important

Welding process: How do I weld?: process

Manual arc welding - learning to weld

Inert gas welding MIG, MAG and TIG

Welding process: How do I weld?: process

Inert gas welding and electrode welding in one device

Similar to electrode welding, inert gas welding also works. It also requires a high voltage, a ground on the workpiece, an electrode and a shielding gas that surrounds and protects the weld.

The advantage of inert gas welding, however, is the automatic feed of the welding wire, which ensures a uniform welding pattern. In addition, the shielding gas replaces the sheath of the electrode so that less harmful fumes are produced when burning.

The disadvantage, on the other hand, is the additionally required protective gas, which is available during the welding process and must be stored properly. As a result, inert gas welding is used in only a few private workshops.

With more technology, inert gas welders are just a bit more expensive, but often have the advantage that they can be used for inert gas welding as well as for electrode welding or manual arc welding. Corresponding welding machines provide the required voltage for both welding processes and can be operated with or without a hose package for inert gas welding.

The welding process is similar in both welding processes:

Between theElectrode (3) and theWorkpiece (7) an arc is generated, which leads to a high temperature development and thus theMolten bath (5) leads. Since there is no sheathing of the electrode, the requiredInert gas (4) directly over the so-calledHose package (1) supplied and protects, as in the electrode welding the molten bath and theWeld seam (6) against inclusions and corrosion. To transfer the required voltage without loss to the welding wire, the welding wire is in aContact sleeve (2) guided, which holds the welding wire in position and transmits the electrical energy

Welding process: How do I weld?: welding

The welding wire is fed automatically.

Welding process: How do I weld?: welding

Process during inert gas welding

Differences in MIG, MAG and TIG welding

The metal inert gas welding (MSG) can be divided into other different methods. Decisive for this is the supply of inert gas or filler material, the welding wire.

  • Metal inert gas welding (MIG) - Inert comes from Latin and means "idle". In metal inert welding, this means that the shielding gas has no direct influence on the weld seam. It does not alter the composition and properties and only prevents corrosion of the molten bath.
  • Metal active gas welding (MAG) - As the name implies, the gas actively engages in the welding process, combines with the metal and changes its properties.
  • Tungsten inert gas welding (TIG) - In addition to the direct supply of the welding wire, in which the welding wire simultaneously serves as an electrode, a non-consumable tungsten electrode can be used and the filler material (welding wire) are supplied separately.

What is a welder inverter?

Welding process: How do I weld?: welding

Welding inverters can be small and handy.

The welding process requires a high current at a low voltage. This is obtained from the power grid with high voltage and lower current and must therefore be converted. In the form of the transformation also the naming differs.

  • Welding Trans Formater - A transformer consists of at least two coils - the primary coil and the secondary coil. If an alternating voltage is applied to the primary coil, a magnetic field is created which is transmitted via an iron core. On the opposite side is the secondary coil, which performs the process reversed and converts the magnetic field back into electrical voltage. The newly generated voltage is proportional to the number of windings. More windings of the primary coil give a higher and less a lower voltage. In this way the input voltage can be stepped up or down. Depending on the power, the coils must be dimensioned accordingly, which leads to the required iron core to a high weight.
  • welding inverter An inverter uses the same principle, can use smaller transformers by rectifying the mains voltage and a much higher frequency (generated by power semiconductors). The higher the frequency generated, the smaller the transformer used can be. This allows much smaller and lighter welding equipment with a higher efficiency.

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Video Board: How to Arc Weld | Welding