Contec MD multiplies endurance times in automated welding
The first generation of the Contec contacting system set new benchmarks when it came out just over three years ago. In automated welding, it prolongs the endurance time of the torch several times over compared to when a conventional nozzle is used. This is particularly true of systems being used to join aluminum. Users from a number of different industries voiced a wish to enjoy the same advantages in steel welding as well. Fronius has now met this demand by bringing out the second-generation Contec MD: This boasts endurance times that are between five and fifteen times as long, in the joining of both aluminum and steel. Among its other benefits are higher process stability and system availability, exact TCP (tool center point) and a flawless weld pattern.
The conventional contact tip of an arc-welding torch is a wearing part, with all the classic drawbacks that this entails. While being fed through, hard welding wires gradually abrade the cylindrical inside diameter into a conical shape. This causes the electric contact zone between the tip and the electrode to migrate uncontrollably in what tends to be the opposite direction from the wirefeed. After only a relatively short time, the contact tip needs replacing, which means interrupting machine operation. With the soft electrodes used in aluminum welding, it is these which abrade and then alloy to the inside of the contact tip – until this blocks wire-travel. When the wire is stopped in this way, the arc may burn as far as the contact tip and damage the torch. Contec MD greatly lessens these influences and risks.
This further-enhanced contacting system from Fronius guides the wire in V-shaped grooves that are now 12 mm long, under a defined contact pressure. Even after the half-shells start to wear, a mechanical spring ensures that the contact zone remains constant, providing a defined current transfer. In conjunction with the stable TCP, and without needing any readjustment, this results in high process stability, which also has a positive effect on seam quality.
The increase in lifespan over that of conventional contact-tips – in specific cases this may mean over fifteen times longer – drastically increases productivity. This is because every time a contact tip has to be changed, work has to be stopped, causing downtime and outage costs. Fewer interruptions mean higher system availability. They also reduce rejects and post-weld machining work. The new concept has a further economic benefit: Contec MD (MultiDiameter) is designed for electrode diameters from 0.8 mm to 1.6 mm. At the end of their long service life, the only parts the user needs to replace are the two half-shells. The nozzle stock, compression spring, clamping nut and spatter-guard are all reused. The Contec MD can be used on the latest range of Robacta, Robacta Drive and Robacta Drive CMT gas- and water cooled torches. It has been trialled up to 300 A for welding low-alloy steels, and up to 200 A for CrNi steels.