Frötek-Kunststofftechnik uses Dalex welding machine technology for the production of stranded wire cables with wire end contacts and produces a wide range of variants in large quantities fully automatically within a very short time.

The expertise of Frötek-Kunststofftechnik with its main plant in Osterode am Harz ranges from injection molding of high-performance thermoplastics and multi-component injection molding to system developments such as Moldflow, resistance, ultrasonic and rotation welding, the creation of prototypes and the construction of small systems and tools as well as the assembly of components. Another important pillar is battery technology. Whether flexible or rigid, sleeve or welding technology, Frötek is internationally active in the production of a wide variety of connector cables. One of the secrets of the company's success lies in its production technology: a fully automatic welding system from Dalex is used to assemble a wide variety of stranded cables with wire end contacts.

One system for countless variants

"Frötek wanted to optimize its stranded cable production and combine several work steps. The company was looking for a system solution that could perform all tasks fully automatically, from feeding the cable to measuring, cutting and stripping processes, feeding the wire end contacts, welding the contacts on both sides and ejecting the finished products. The main challenge was the large number of variants. Welding tube connectors with cross-sections of 16, 25, 35, 50, 70 and 95 ^mm2 and lengths of 75 to 300 mm in 1 mm increments had to be produced reliably, repeatably and productively in the shortest possible time and in large quantities. The result is a 16-station rotary transfer assembly machine that is precisely tailored to the requirements," says Marcel Groß, Group Head of Mechanical Design at Dalex.

The stranded cable is fed into the system from the coil/coiler unit using dancer control. The cable is measured, stripped and cut to length to convert the various diameters and lengths. The conveyor belt then transports the corresponding cable section to the removal station on the turntable. A sensor automatically detects the cable. The cable is then removed from the conveyor belt, inserted at the turntable and tensioned.

Double welding shortens times

"The system is equipped with two welding stations. They each fit one end of the cable with the end contacts. As they work simultaneously, there are always two cables in the system and the quantities can be completed much faster," says Groß. The processes around the two welding machines are identical: a spring-mounted handling unit checks the cable, balances the lengths and brushes the copper wires to remove oxidation residues for optimum welding. It is then inserted into the welding station.

The copper end contact lugs also enter the station automatically. During the projection welding process, the system monitors the welding current, voltage and welding path in order to achieve optimum results. Between the two welding stations, a servomotor-driven handling unit removes the cable, turns it, moves it into position and inserts it into the component holder of the welding machine.

Automatic final inspection

Marcel Groß: "After welding, the system automatically checks the welded cables. If the parts are OK, a needle embosser marks the contacts. They are then ejected from the system on a conveyor belt. If the parts are faulty, they are automatically separated before marking. In the final station, a light barrier checks whether the component holder is empty after removal."

The advantages of the 16-station rotary transfer assembly machine are clear to see: Thanks to the combination of the previously separate work steps, the production of stranded cables is more efficient and therefore more productive. The many different variants can be covered with a single system. And the parallel welds significantly reduce production times. "Since purchasing the Dalex systems, we have already completed a remarkable 200 million welds - with outstanding quality. The combination of our own stringent rope monitoring techniques and our cable extrusion systems with the Dalex technology ensures that we have had very few welded part failures to date," says Sebastian Mathes, Director Electrical Engineering / New Markets at Frötek. The company already has three of these systems in use.