The Challenge of Thin Sheet Welding in Mechanical Engineering

All Parameters at a Glance

The welding machine is operated with a central rotary push-button combined with a touchscreen. The quick change function that allows users to switch between properties, processes and functions is particularly practical. If you touch the respective prompt on the status bar of the display, you can immediately access the available parameters.

On the central display of the TPS 320i, the specialists can see all the relevant control variables and adjust them one by one. Innovative animations support the welding specialists when entering parameters. For example, there is a graphical representation of how a-dimensions change as arc length corrections are made, depending on whether a positive or negative correction is entered. The “synergic function,” which automatically detects how settings and corrections affect other relevant parameters, is responsible for this. 

Easy Jobs and WeldConnect App

Even if the operation is carried out with welding gloves, the machine responds perfectly. Recurring parameter combinations for specific tasks can be saved as personalized easy jobs at the touch of a button. For example, when welding a 3 mm thick steel plate, job 1 is used. If you are welding a 5 mm thick chrome-nickel plate, use job 2. If a JobMaster welding torch is used, these jobs are available directly on the welding torch. The practical Fronius WeldConnect app for Android and iPhone is helpful for setting the welding specifications. As soon as the base material, filler metal and shielding gas have been scanned using a QR code and the weld seam profile, material thickness, welding process and welding position have been entered on the mobile phone, the welding specialist can use NFC (near-field communication) to transfer the calculated values to the TPS 320i or to a mobile phone belonging to another employee, who in turn transfers them to his/her welding machine.

Robot Applications Make Welding Attractive at Knoll 

Welding does not necessarily have the best image. The profession is often associated with noise, harmful welding fumes and monotony. At the same time, the job is quite demanding, at least when robots come into play. Then, in addition to welding knowledge from electrical engineering to metallurgy, programming skills are also required. There is huge demand for welding technicians who know how to program robots, and they are well paid. 

Many companies, including Knoll, now create their welding programs offline, i.e. separately from the robotic welding system on a PC or laptop. This not only minimizes downtimes, it also offers the big advantage of welding simulation on the digital twin. In this process the software identifies axis limits, calculates starting points, limit positions and journeys, and sets teaching points independently. Obstacles are visualized and welding torch positions corrected on time, before the first weld is made.

Knoll now also uses a cobot system. It is easy to use and does not require traditional programming skills. If you want to create a weld path, you move the welding torch point by point along the joint line and save the points one after the other. The weld path and sequence are automatically calculated by the software, recorded, and are permanently available for later jobs. The system at Knoll uses CMT technology. Due to its extremely stable arc, combined with reduced heat input and low spattering, today the renowned “cold” MIG/MAG welding process from Fronius is used worldwide in plant, machine, power plant and automotive construction, in the aircraft and food industries, and in medical technology. It plays to its unrivaled strengths, especially when it comes to thin sheet welding.

“Operating cobots is intuitive and has a certain fun factor. This is especially true for young welders. They think cobot welding is cool; among other things because it is as easy as using a smartphone. Anyone who is familiar with using a smartphone can operate a cobot within a few hours. If this is enclosed and equipped with a fume extractor, the welding specialists are also protected against unhealthy welding fumes,” says Kleck, sticking up for cobots. 

Quality-oriented but with a Heart

It is typically Swabian that, alongside the social development of the town of Bad Saulgau, which they generously support with sponsorship, precision is close to the hearts of the two managing directors Matthias and Jürgen Knoll, including during welding. This means that they need specialists who uphold the company standard. Being aware of this, Knoll believes that the company’s success is above all the sum of the performance of many skilled employees who give their all for the company. Profits are used for site development and are reinvested in the company. At Knoll, they think ahead in terms of generations, not just quarterly figures. The region and the employees benefit from this.

Health and Safety Are a Top Priority

Healthy employees are not a given, and neither are committed ones. Since one depends on the other, Knoll uses ergonomic workstations and the best possible personal protective equipment. All welding tables are height-adjustable, and automatically darkening welding helmets plus fresh air supply have long been standard. In addition to this, the room air is renewed four times per hour. 

“Workplace ergonomics is an important topic,” Riebsamen explains. “Not only in terms of health, but also from a profitability perspective. Simple, individualized operation, short distances between the component and the welding machine: all this has a motivating effect, saves valuable time and increases the productivity of welders.”

Of course, component safety and quality also play a crucial role. The experts at Knoll therefore apply various testing methods, such as dye penetration testing (PT), to check each individual component. This is a fast, effective method that shows up surface cracks and other defects such as pores. It is also suitable for complex geometries and can be carried out on workpieces of all sizes. Even small errors that are not visible to the naked eye can be detected with PT and then corrected by the welding specialist.

During the dye penetration testing, a fluorescent dye is applied to the surface of the workpiece to be tested. This penetrates into existing cracks, pores and defects. It is then illuminated with a special lamp or sprayed with a developer. Any defects are immediately visible to the examiners because they are surrounded by the fluorescent dye.

In line with its motto “it works,” Knoll Maschinenbau GmbH supplies its customers with reliable individual plants and systems that are easy to operate.