A welding machine is a central working tool in metal construction, deconstruction, and repair. Whether for temporary auxiliary structures, adapter plates for attachments, or repairs to steel components—the thermal joining of metals complements mechanical methods such as concrete demolition shear, hydraulic splitter (wedge) for stone and concrete, or steel shear. In many application areas of Darda GmbH, such as concrete demolition and special deconstruction, in building gutting and cutting, as well as in rock excavation and tunnel construction, the interaction of hot work and cold separation and splitting methods is crucial for safety, quality, and efficiency.
Definition: What is meant by welding machine
A welding machine is a power source with control and feed equipment that provides the arc for the thermal joining of metallic materials. It converts mains or generator power into a welding current suitable for the respective process and controls parameters such as current, voltage, and arc characteristics. Depending on the process, the welding machine includes an electrode holder or torch, potentially a wire feeder and shielding gas supply. The goal is to produce a permanent, integral joint with defined weld bead geometry and strength.
Design and operation of a welding machine
Modern units typically operate as inverters: they rectify and switch the electrical energy at high frequency to achieve a stable arc, low losses, and compact designs. Key assemblies include rectifier, power electronics, control unit, cooling, (for MIG/MAG) wire feeder, and the connections for the ground cable and torch.
Duty cycle and performance reserves
The duty cycle (DC) indicates how long a welding machine can operate at a given current within ten minutes (e.g., 60% DC at 200 A). On the construction site, reserves are important because ambient temperature, cable length, and generator set operation influence usable performance.
Power supply on the construction site
Welding machines are supplied via 230 V or 400 V. When operating from a generator set, adequate apparent power, voltage stability, and protective measures must be ensured. Parallel operation of other loads—such as a hydraulic power pack—should be coordinated to avoid voltage dips. Long extensions increase voltage drop; large cross-section cables and short runs are advantageous.
Welding processes in deconstruction, steel and plant construction
Different processes are used depending on the task. Selection criteria include material, plate thickness, accessibility, quality requirements, and weather.
- Shielded metal arc welding (SMAW): robust, not very sensitive to wind, ideal for assembly, anchor plates, repairs. Dry, properly matched electrodes are crucial, especially for higher-strength steels.
- MIG/MAG: high deposition rate, productive in the workshop and on the construction site with a mobile wire feeder. Plan for shielding gas logistics and wind protection.
- TIG: precise, clean welds, suitable for thin-walled parts, heat-tint-free work on stainless steel (with forming gas). Lower deposition rate, but high weld quality.
- Carbon arc gouging (with inverter): for removing defects or opening cracks prior to repair welding.
Materials and heat input
Welding alters the microstructure in the heat-affected zone (HAZ). Preheating, interpass temperature, and controlled cooling reduce the risk of hydrogen-induced cracking. Electrodes and filler materials must match the base material; moisture in coated electrodes must be avoided.
Welding on high-strength and wear-resistant components
Components such as grapple arms or blades of steel shear and concrete demolition shear can be made of high-strength or quenched and tempered steels. Inappropriate heat control can negatively affect hardness and toughness. Repairs must be carried out with suitable filler materials, defined preheat temperatures, and proper procedures. Welds on safety-relevant components should only be performed after approval and in accordance with recognized rules.
Typical applications in concrete demolition and special demolition
Welding machines are used around concrete demolition shear, hydraulic splitter (wedge) for stone and concrete, as well as steel shear primarily for auxiliary structures and adaptations. Examples:
- Producing and welding on lifting points and lifting lugs on steel beams prior to controlled cutting with steel shear or Multi Cutters.
- Manufacturing adapter plates and base plates for mounting or positioning tools and protective covers.
- Temporary bracing and shoring before concrete members are selectively crushed with concrete demolition shear.
- Repair welding on steel parts of fixtures and the work platform, provided material, process, and approvals fit.
Cold cutting instead of hot work: differentiation and combination
In deconstruction, cold methods are often advantageous: they create no ignition sources and minimize secondary damage. Concrete demolition shear process reinforcement and concrete without flame; hydraulic splitter (wedge) for stone and concrete open components in a controlled and low-noise manner. When opening tanks and vessels, tank cutters as a cold cutting process are an important option. Welding remains useful where metals must be joined, supported, or adapted.
Occupational safety, fire protection and hot work permit
Welding is part of hot work. Depending on the environment, organizational and technical measures are required to protect people, the structure, and operations. This is especially true in building gutting, when cutting in existing buildings, and in special operations.
- Prepare a risk assessment, hot work permit, and fire protection concept.
- Clear combustible materials and fire loads, provide barriers and spark curtains, keep extinguishing agents ready.
- Avoid potentially explosive atmospheres; process tanks and lines only in a safe, gas-free condition.
- Ventilate, extract fumes, use suitable PPE; consider welding fumes and UV radiation.
- Plan a fire watch during work and adequate follow-up inspections.
Joint preparation, execution and testing
Good joints begin with preparation: clean joint faces, remove oxides and coatings, bevel edges, set gap and open the root. Tack welds fix position. Stringer beads improve penetration and control. Rework includes slag removal, visual inspection and—depending on requirements—non-destructive testing. Documented parameters (WPS) and qualified personnel ensure reproducible quality.
Selecting a welding machine for the construction site and the workshop
The right power source depends on the application. For mobile deconstruction, robustness, simple operation, and suitable processes matter; in the workshop, often productivity and process variety.
- Process: SMAW for universal assembly; MAG for high output; TIG for precision.
- Power/DC: sufficient reserves for thicker sections and continuous duty.
- Mobility: weight, carrying concept, IP rating, generator compatibility.
- Accessories: long ground cables, suitable electrodes/wire, gas management, gouging equipment.
- Quality functions: arc force, hot start, synergy programs, stable wire feeding.
Interaction with Darda GmbH hydraulic tools
On construction sites, welding machines often work alongside a hydraulic power pack, concrete demolition shear, hydraulic splitter (wedge) for stone, combination shears, Multi Cutters, steel shear, and tank cutters. Workflows should be planned so that sparks, heat, and welding fumes do not impair hydraulic components, hoses, and seals. Place the ground clamp close to the joint area to avoid stray currents in adjacent tools. Protective plates, stops, and adapters can be welded on or bolted as needed—depending on material, load case, and approval.
Maintenance, care and transport
Regular care increases operational safety: keep airways clear, clean filters, check cables and connections, store electrodes dry, protect wire from moisture. During transport, impact-resistant housings and secured cylinders (for shielding gas) prevent damage. Documentation of inspection intervals and visual checks supports safe operation.
Terminology notes and additions
Welding machines serve joining; cutting can be thermal (e.g., oxy-fuel cutting, plasma cutting) or mechanical. Where sparks and flame are undesirable, cold methods offer advantages: concrete demolition shear for concrete, hydraulic splitter (wedge) for controlled splitting, tank cutters for safely opening suitable vessels without a hot ignition source. The combination of cold separation and targeted welding enables safe and efficient approaches in many application areas of Darda GmbH.