Why is welding called a permanent connection

Welding: process, dangers, occupation, work technique

welding is (according to ISO 4063) a process for the permanent joining of two or more materials and belongs to the group of joining processes. With this type of joining, workpieces are fused together by applying force or heat.

Welding offers several advantages compared to screwing, riveting or soldering. This includes cost savings and stronger connections.

Synonym (s): welding, joining

An overview of the welding processes

Classification of welding processes

There are several welding processes, which are broken down according to material, technology and energy. The main distinctions must be made between fusion welding and pressure joint welding. Depending on the process, the temperatures can be between 1000 and 3200 ° C.

The welding processes are classified according to different criteria:

  • material: Metals, thermoplastics (this includes plastic welding) and other materials (combinations of several materials are also possible)
  • energy: Use of thermal or mechanical energy
  • Characteristic / technology: Fusion welding and pressure welding
  • purpose: Joining or coating
  • production: manual, partially or fully automated

Guide: Choosing a Welding Process

The above criteria can be used to decide which welding process is the right one. In spite of everything, you have to choose additional criteria get noticed:

  • Component geometry
  • Welding position
  • Accessibility to the welding point
  • Quality requirements
  • Quantities
  • costs
  • Expenditure of time

Differentiation between fusion and pressure welding processes

The Fusion welding process to run without effort from. Instead, the two workpieces (often metallic) are melted on the joining surfaces. The joining process can then take place with or without additives.

The Pressure welding process however under force / pressure applied. Here, the joining partners are not melted, but connected by pressing them together. This is usually done without additives and can be combined with locally applied heat.

Procedure in welding

Many of the procedures listed have been used for a long time, but some have only been developed for special cases.

To the Fusion welding process counting:

  • Aluminothermic welding / thermite welding
  • Electroslag welding (RES welding)
  • Gas welding (G welding)
  • Cast fusion welding
  • Resistance fusion welding
  • Beam welding
  • Arc welding / electrode welding (E / MMA welding)
    • Metal arc welding
    • Gas-shielded welding (SG welding)
      • Metal active gas welding (MAG)
      • Metal inert gas welding (MIG)
      • Gas-shielded metal arc welding (MIG / MAG)
      • Tungsten gas welding (TIG / TIG)
      • Orbital welding
      • Plasma welding
    • Submerged arc welding (submerged arc welding)

To the Pressure welding process counting:

  • Diffusion welding
  • Fire welding
  • Gas pressure welding
  • Cold pressure welding
  • Arc pressure welding
  • Press butt welding
  • Friction welding
    • Ultrasonic welding
    • Roll seam welding (RR welding)
    • Rotational friction welding
  • Resistance welding
    • Flash butt welding (RA welding)
    • Projection welding (RB welding)
    • Spot welding (RP welding)

Adviser: which procedure for what?

Since there are a large number of processes in welding and the respective requirements vary, few processes are used most frequently.

For handyman and their simple / everyday use, arc welding or electrode welding (E-welding) is recommended. This does not require much practice and the workpiece can be welded without distortion even under adverse conditions. However, alloyed steels (such as stainless steel) cannot be welded and occupational safety must be strictly observed.

If non-ferrous metals or non-alloy steels are to be welded, [inert gas welding] with its MIG and MAG variants is recommended. This type of welding is cleaner and for Beginner suitable. However, in contrast to electric welding, higher costs must be taken into account.

Similar to MIG / MAG welding, TIG welding can also be used for beginners, in which alloy steels can also be welded. Here too, the cf. high acquisition costs.

Conclusion: A DIY welder should use MAG welding. With this welding process, most work (with unalloyed steels) can be done easily. You can find more information here. If you only need to weld infrequently, it is advisable to buy an electrode welding transformer.

Applications of welding machines

Robots in action during the welding process

The welding processes and thus machines can be used for a wide variety of areas. The most commonly used methods are MIG, MAG and TIG. Areas of application include:

  • Automotive industry
  • Household industry
  • Pipeline construction

examples for welded products include:

  • Railway rails (thermite welding)
  • Bodies
  • Tube
  • Poles
  • Tanks

Occupational health and safety

Occupational health and safety are the top priorities in (electric) welding. The following hazards must be observed urgently:

  • the resulting heat
  • the flying sparks
  • the UV rays
  • the bright arc

To the Osh Covering the body with suitable work clothes, gloves and an apron also counts. Simple protective goggles do not protect against UV radiation, which is why a protective helmet should be worn in the best case. Any spectators should avoid looking into the arc.

Since additional voltage is built up during electric welding, the workplace should always be protected from moisture. Many welding processes use toxic gases, which can be prevented by a ventilated and fire-proof work area.

A briefing is mandatory for all workers, as stipulated by the Occupational Safety and Health Act. The professional association for wood and metal (BGHM) also provides a list of all other welding rules.

Work technique / instructions

Basically, every welding process differs from one another. The following things must be done with the manual editing of the workpieces are observed:

  • When welding, the respective workpieces must be clean. Therefore, rust and any paint that may have been applied should be sanded off before the actual welding process.
  • First, the workpieces have to be connected with a spot weld on the joining surfaces. In this way, the workpieces can still be processed afterwards and the material does not warp when heated.
  • During the welding process, slag is created at the weld seam, which has to be knocked off or sanded off. Slag refers to the waste that is left behind when the materials melt.
  • After removing slag, the seams are completely welded through.
  • The welding current used must be adapted so that the connections between the workpieces hold correctly or do not melt through.
  • Correct posture should avoid cracks and inaccurate connections.
  • The correct settings for gas flow, welding current and speed must be observed.

Both alcohol for large-scale industrial use and household use is of the appropriate quality quality assurance necessary during the welding process. In the end, it is therefore important to ensure that the welded connections and seams are tight. The Weld joint quality says something about how acceptable irregularities in the weld seam are. Wikipedia provides its own articles on the following criteria:

  • Welding defects
  • Weld defects
  • Quality of the pressure welding
  • Quality of fusion welding
  • Quality assurance in welding

Welder (training)

The Welder / universal welder refers to a job in metal processing. They are experts in a wide variety of welding processes and cutting tools and work in a wide variety of industries:

  • Locksmiths
  • Metal construction
  • Machine manufacturer

Welders use different materials in their work. This includes various metals and / or thermoplastics. Your tools are mostly manual or automatic welding machines.

The profession of welder is about one training he learns. The scope of the training depends on the respective company. Although the DVS (German Association for Welding and Allied Processes) regulates basic and advanced training, there is no uniform duration. A retraining a welder is possible at any time, e.g. through TÜV Rheinland. There are no specific professional requirements for this. The duration can also vary here and range between six weeks and several months. There is also the option of taking welding courses, which usually only last a week and end with a TÜV test.

The salary of a welder depends on the size of the company as well as the size of the job. Collective industry surcharges in the metal and electrical industry are often added. So the salary can increase after just a few weeks.

The Future prospects The welder's profession is not bad despite many industrial developments. Around 70,000 people still work in this profession in Germany.

Virtual welding

Fronius presents "Virtual Welding" - a welding simulator for virtual welding, especially developed for trainees

The topic Virtual welding has become a constant topic, especially in times of Industry 4.0. Both beginners and experts have the opportunity to work with welding simulators during their training or further education. The advantages of this technology are:

  • Efficiency
  • Risk minimization
  • Resource conservation

Large companies such as Mercedes-Benz or MAN Trucks & Bus are now also working with virtual welding. Daimler now offers the new trainees the opportunity to operate systems in their own Industry 4.0 laboratory using a tablet PC - including virtual welding. Fronius International offers the welding robot Virtual Welding, which also works with VR / 3D glasses.

Facilities

  • DSV: German Association for Welding and Allied Processes e.V.
  • GSI: Union for Welding Technology International GmbH
  • SLV: Welding training and research institute (e.g. Berlin, Duisburg, Fellbach, Munich)
  • WorldSkills Germany e.V.: Professional competitions within Europe (EuroSkills) or worldwide (WorldSkills)

Construction of welding equipment

Simple construction of a MIG welding machine

Before the Construction of welding systems can be explained, the following points must be taken into account:

  1. Who is using the device?
  2. What experience does he have in handling welding equipment?
  3. For what purpose should the welding machine be used?
  4. Which welding process is right for it?
  5. What is the place of work?
  6. What is the budget?
  7. How many workpieces have to be welded?

After considering these points, it is clear whether hand operated or automated Welding systems are used.

The illustration opposite shows the structure of inert gas welding devices (hand-operated).

Details on the automated welding systems can be found on the respective manufacturer's pages.

Manufacturer of welding equipment / machines / accessories

This overview shows which manufacturers are available for welding systems and which area each company covers.

  • Bielomatik is one of the few companies that offers machines for all common welding processes. The specialty is plastic welding.
  • KUKA offers industrial robots for arc welding and laser welding. The company relies on partners such as EWM and Migatronic.
  • REHM is a manufacturer of welding equipment for all types of inert gas welding: MIG / MAG, TIG, MMA and plasma cutting.
  • Lorch: The company offers welding systems for gas-shielded welding. In addition to the hand-operated welding equipment, there are also automatic / robotic welding systems.
  • MERKLE is a manufacturer of welding machines, automatic welding machines and welding torches. The Bavarian company, for example, offers a large welding cell with robot automation.
  • CLOOS_ In addition to welding systems for laser welding and TIG welding, the range also includes plasma cutting machines. You can choose between manual and automated welding devices, as well as welding robots from the QIROX product brand.
  • EWM is a manufacturer of welding equipment. For this purpose, the company offers welding (equipment) accessories or welding consumables.
  • Migatronic: The Danish company Migatronic builds welding machines for MIG / WIG / MAG / E-manual / plasma welding.
  • Roleff develops WIG / MIG / MAG welding machines, plasma cutting machines and laser welding machines. The laser welding systems have a power of 300 watts and can be used mobile as well as stationary.
  • Würth develops welding systems for MIG / MAG welding. The company also offers welding accessories and other welding equipment.
  • Gerlach welding technology supplies welding machines, welding devices, welding consumables and plasma cutting machines for all applications. Products for the area of ​​occupational safety are also offered.
  • Fronius from the Stuttgart area is a service and product provider for welding processes. The portfolio includes MIG / MAG / TIG welding machines, complete welding systems and digital products such as Weldcube and Weldconnect.

Category "Welding: Process, Hazards, Occupation, Work Technique"