An automated longitudinal seam welding system guides the torch carriage at a constant speed along the joint and produces reproducible longitudinal seams up to 4,100 mm—without the need to manually guide the torch during welding. Schnelldorfer Maschinenbau develops these welding machines as a finely tuned combination of a clamping system, control technology, and welding head. We know what really matters: precision and repeatability.
Precision Welding: How an Automated Longitudinal Seam Welding System Works
An automated longitudinal seam welding system first positions and secures the workpiece. The torch carriage then travels along the seam at a constant welding speed. At the same time, the control system regulates key parameters such as current, feed rate, and gas flow along the entire weld length. This controlled torch guidance reduces typical welding defects such as penetration notches, porosity, and lack of fusion, and lays the foundation for consistent weld quality.
The clamping system is equally important: Flat clamping benches hold the joint area in a defined position along its entire length and promote uniform heat dissipation. This allows for better control of welding distortion than with point-by-point clamping.
The practical advantage here is that the stored welding process values can be retrieved later exactly as they were. In addition, sensors can be integrated into the system to monitor relevant welding parameters and report deviations early on. This results in a high degree of automation, particularly in mass production, because quality no longer depends on individual manual movements but rather on a system with reproducible settings.
TIG Welding, MIG, MAG, and Plasma: Processes for Different Requirements
Automated longitudinal seam welding systems can be operated using MIG, MAG, TIG, and plasma welding. The choice of welding process depends primarily on the material thickness, the material being used, the desired surface finish, and the required seam quality.
Welding Processes at a Glance
- MIG: Metal Inert Gas welding, primarily used for aluminum and copper. High welding speed and good weld quality.
- MAG: active shielding gas; the standard process for steel and carbon steel. Very cost-effective, especially for high-volume production.
- TIG: TIG arc welding with a non-consumable tungsten electrode, providing maximum control over the molten pool. For exceptionally clean and precise welds.
- Plasma: a confined arc with high energy density for thin-walled and challenging materials. Deep penetration and a narrow heat-affected zone.
Quality Standards in Welding Technology: What a Good System Must Be Able to Do
In industrial welding technology, a visually clean weld alone is not enough. The finished welded joints must also meet certain requirements and be subject to verifiable evaluation. There are various standards and regulations governing this, including the following:
- ISO 5817: Evaluation of Irregularities in Fusion-Welded Joints
- ISO 3834: Quality Requirements for Welding Production
- EN 1090: relevant for the design of load-bearing steel and aluminum structures
- CE Conformity: Pertains to the safety and conformity of the machine
- ISO 9001: describes requirements for a company's quality management system
The technical design of the machines also contributes to process reliability. High-quality systems can achieve positioning accuracy in the range of ±0.1 mm. The strength of a weld, however, always depends on the material used, the geometry, and the selected welding process; depending on the application, values starting at 500 MPa are possible.
Modular control systems also offer the advantage that functions and process monitoring can be expanded at a later date. This allows an existing longitudinal seam welding system to be flexibly adapted to changing production requirements at any time, without having to replace the entire machine.
From stainless steel to tube manufacturing—the materials and components
An automated longitudinal seam welding system processes steel, stainless steel, aluminum, and copper up to a material thickness of 15 mm. With appropriately adjusted parameters, titanium, special alloys, as well as duplex and nickel-based materials can also be welded. As a result, the systems cover a wide range of materials and industrial applications.
However, the specific design depends at least as much on the component geometry: For sheet metal, for example, the weld length is the primary factor determining the required machine size. For particularly long workpieces, the series covering component lengths up to 4,100 mm also addresses the upper end of the product range.
In tube manufacturing, on the other hand, the focus is more on diameter and clamping. Tubes ranging from 80 to 1,250 mm can be secured in a specially designed clamping bench and welded lengthwise. Cooling the clamping jaws promotes even heat distribution and helps maintain the stability of the component’s entire geometry during the welding process. This ensures clean and strong welds all around.
Where is automated longitudinal seam welding beneficial in manufacturing?
Automated longitudinal seam welding is particularly cost-effective when components are regularly manufactured with straight, uniform, and permanently leak-tight weld seams. Especially for recurring geometries and higher production volumes, automated longitudinal seam welding machines ensure consistent quality and shorter processing times.
Typical applications include:
- Automotive Industry: Manufacturing of welded tanks and containers that require permanently leak-tight and reproducible welds
- Food Industry: Manufacture of stainless steel containers, water tanks, and storage tanks with smooth, hygienically sound welds
- Mechanical Engineering: Production of housings, containers, and elongated components where dimensional accuracy and consistent seam quality are critical
- Construction Industry: Manufacturing of longitudinally welded pipes and components, the machining of which must be tailored to their diameter, dimensions, and material thickness
Schnelldorfer Maschinenbau: Automated Longitudinal Seam Welding Machine and More from the Experts
Schnelldorfer Maschinenbau develops and manufactures longitudinal seam welding machines and custom machines at its Schnelldorf facility and has been specializing in welding technology since 1980. We do not view the clamping system, control system, and welding head as independent components, but rather as a coordinated unit. That’s why we also manufacture custom solutions, which our team will gladly integrate into your ongoing production process upon request. For results that are truly tailored to your needs.
If you're looking for a welding solution that offers greater precision, efficiency, and repeatability, please contact us. We look forward to working on your project!
Frequently asked questions (FAQ)
What are automated welding processes?
Automated welding processes handle torch guidance, feed, and parameter control mechanically. The operator starts and monitors the stored program, while the system performs the actual welding process in a reproducible manner. As a result, repeatability remains consistent regardless of manual movements and fluctuations during a shift.
What is the most difficult welding process?
TIG welding is one of the more demanding processes in manual welding. The torch and filler metal are guided separately, while the distance, speed, and molten pool must be controlled simultaneously. In an automated system, however, the control system takes over many of these tasks, thereby maintaining a constant torch distance, welding speed, and current.
How many liters of gas per minute are used in MAG welding?
In MAG welding, the shielding gas flow rate is often between 10 and 18 l/min. As a rough rule of thumb, the gas flow rate in liters per minute is often set equal to the gas nozzle diameter in millimeters—so for a 12-mm nozzle, this would be approximately 12 l/min. However, the actual appropriate value depends on the nozzle, the workpiece, the welding position, and the environmental conditions. In automated systems, the specified gas flow rate can also be conveniently saved as a parameter and reliably recalled each time a program is started.
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