Welding Quality for Freight Wagons

Welding Quality for Freight Wagons

Deutsche Bahn’s freight wagons, which are used on wide and standard-gage railways, are manufactured by the company Tatravagónka in Tlmače, Slovakia. The wagons have to withstand enormous tractive forces, making the required welding challenging. To get the job done Tatravagónka is using TransSteel 5000 Pulse from Fronius, a welding machine that is ideal for welding steel and carbon steel alloy subassemblies.

Tatravagónkas product range is closely linked to that of its Poprad-based parent company, which has a portfolio of more than 100 different types of wagons. Its Tamns-design 4-axle wagon with sliding roof was awarded "best mechanical engineering product of 2018" in Slovakia. This wagon design has eliminated the risk of moisture ingress into the interior, a common problem when transporting raw materials. Tatravagónka also owns a patent for steel folding roofs with double labyrinth seals, making the bodies watertight.

Certified for rolling stock construction

The company is certified under EN 15085-2, classification level CL 1 for railway applications – Welding of railway vehicles and components and under DIN EN ISO 3834-2 – Quality requirements for fusion welding of metallic materials. They employ experienced welders who weld in compliance with its internal Welding Procedure Specifications (WPS).

Quality as a benchmark – including welding machines

The experts at Tatravagónka rely on the TransSteel 5000 Pulse from Fronius. With up to 167 optimized characteristic curves, it includes process variants that are in demand in many industries. Its design features the pulse function, which enables higher welding speeds for larger material thicknesses while also generating significantly less welding spatter and reworking compared to the standard process. If welding is performed in awkward positions using the pulsed arc (e. g. overhead), the arc pressure can be increased using the pulse correction feature. This prevents the weld pool from escaping. The dynamic correction feature can be used if deeper penetration is required for optimal root formation when welding thinner sheets with the standard arc. A harder and more stable arc can be generated by reducing the short-circuit dynamics at the moment of droplet transfer. When welding thicker sheets with the standard arc, a soft, low-spatter arc can be generated by increasing the short-circuiting dynamic. In special 4-step mode, it is also stabilized during ignition by reducing the power. Tatravagónka welders can place uniform welding spots at regular intervals using spot mode. The pause time between the intervals can be individually selected and is therefore ideal for tacking workpieces.

“Welding in overhead and horizontal positions (PE and PC) requires special skills from our welders. The welding equipment also plays a crucial role in achieving the required results,” explains Jaroslav Nemergut, Technical Director at Tatravagónka Tlmače. “Fronius has the perfect welding machine for our needs in the form of the TransSteel 5000 Pulse and its functions for welding heavy steel.”

EasyJobs at the touch of a button

Using the Up/Down welding torch, the welding experts at Tatravagónka can save up to five EasyJobs, which can be selected directly from the torch when the EasyJob Trigger (EJT) is activated. Fronius provides welding characteristics for this that are tailored to welding steel for various tasks:

• STEEL is the universal welding characteristic for quick, easy welding applications.
• STEEL ROOT is the welding characteristic developed specifically for root pass welding. It has gap-bridging ability and the capability to fill wide air gaps.
• STEEL DYNAMIC is a welding characteristic with a particularly hard, concentrated arc. The results include high welding speeds and deep penetration.
• PCS (Pulse Controlled Spray Arc) welding characteristic enables a combination of intermediate and spray arcs, providing deep penetration with minimal spatter.

“The TransSteel is easy to configure. When one parameter, such as the amperage, has been set, the algorithm of the Synergic function automatically calculates the other parameters. Depending on your needs, you can choose between Standard Synergic, Pulse Synergic or Manual,” says welding specialist Rey Jumaquio.

Ready to weld in three steps

The TransSteel's range of functions has been reduced down to the basics. The focus is on the distinctness and easy handling. This allows the welding specialists to concentrate on the weld pool. Whether you are experienced with the TransSteel or using it for the first time, the device is ready for welding in just three steps. Welders use the pressure-active buttons and rotary knobs on the front of the housing to set parameters, such as shielding gas, wire diameter and material thickness. In times of skilled worker shortages, semi-skilled workers can operate the welding machine with only brief training and weld less critical components to the desired quality level.

Precision and Safety

The central control and regulation unit of the TransSteel is coupled with a digital signal processor. Together, they control the entire welding process. Actual data is continuously measured so that the system can react immediately to changes. In this case, rule algorithms ensure the desired state in a split second. This provides three noteworthy benefits for all welders at Tatravagónka: high process precision and reproducibility of welds as well as excellent weld properties.

The universal welding machine also comes with safety features, including the Voltage Reduction Device (VRD), an optional safety device that reduces the voltage between the electrode and the workpiece when required, such as when working in a damp environment. This significantly reduces the risk of electrical accidents caused by arc welding.

Patented multi-lock interface for welding torch

The interface allows Tatravagónka welders to adapt MIG/MAG welding torches specifically to the relevant requirements. The wide choice of torch bodies in terms of lengths and angles ensures that even hard-to-access parts can be easily welded. When in doubt, the best option is a flexible torch body. The Fronius System Connector acts as the central connection point for all media. This enables welding specialists to connect a wide variety of different welding torches.

Easy documentation

Standard-compliant welding is the order of the day at Tatravagónka. This means that the requirements of the Welding Procedure Specification (WPS) need to be strictly adhered to during the welding process. The TransSteel 5000 Pulse’s Easy Documentation option saves the key welding data for each individual weld in CSV format on a USB stick. A Fronius signature is also saved to verify and guarantee the authenticity of the data.

(Source: Fronius GmbH Press Release)