True to original replicas
The company from Fürth-Burgfarmbach is a leading manufacturer of plastic toy vehicles in Europe and produces construction, agricultural, forestry, emergency, and commercial vehicles as well as recreational vehicles in Germany and the Czech Republic. The faithful replicas of renowned brands on a scale of 1:16 focus on high product quality and product safety.
Demanding welding task
A "Personal Water Craft" has recently been added to the product portfolio of Mittelfranken. As the first of its kind, it presented the development department at Bruder with new challenges. With the "Personal Water Craft", the "boat" cannot be injection-molded from one part or assembled from several parts, as is the case with land vehicles. No, here the hull and lid of the boat have to be welded absolutely watertight. This is because the hollow space inside the boat is important so that the boat does not sink in the water later on. Of course, the surface of the boat must not be affected by the welding, the weld seam must be virtually invisible. In order to find a suitable process and a welding machine manufacturer, Björn Ferner, head of process development at Bruder, says that he googled first of all... and was thus able to find a suitable welding machine manufacturer. SONOTRONIC attentively. "The discussions with SONOTRONIC were very professional, there was a specialist knowledge available, which is decisive for us when awarding such projects". After the first contact with Hermann Meth, buyer at Bruder, our sales representative Christine Thieringer visited the factory in Fürth and in cooperation with the developers of Bruder and our application technology team headed by Markus Hecht a suitable solution for the welding task was developed.
Welding device with robot interface
A good half a year after the request, production is now up and running: The two parts, made of blue ABS plastic, are produced on an existing injection molding machine in Bruder's plant. The robot handling of the machine removes the two parts from the injection mold and transports them directly in front of the SONOTRONIC welding device, which is located next to the system. This is a special ECO iSONIC equipped with a soundproof hood, robot interface and sliding table. The machine was designed both for manual operation for the production of prototypes and for automatic operation with loading and unloading by robot handling. An interface allows the connection to the existing removal system of Bruder.
In series production, the handling system first places the hull of the boat in the component holder and then fits the lid precisely onto it. The sliding table moves the parts into the welding machine, and the integrated lifting door closes like a safety device. In just a few seconds, the two parts are welded absolutely tightly and firmly together using ultrasound (Fig. 4). The boat parts were constructed according to the groove (in the lid) and tongue (in the hull) principle. The spring, i.e. the contour inside the fuselage, serves as an energy direction transmitter, which establishes the connection between the upper and lower parts by targeted melting. The weld is not visible from the outside and due to the low thermal load, there are no markings on the component. The component is excited by the vibration of the sonotrode at a frequency of 20 kHz and the force applied via the feed unit. According to the principle of "external and internal friction", the energy direction sensor and the contacted area in the groove plasticize. After a very short cooling phase of 0.5 seconds without ultrasonic action, the two parts are firmly connected to each other along the joining zone.
After welding, the feed unit with the welding tool returns to its home position, the lift door opens and the sliding table extends the welded boat. Since the joining zone has already cooled down, the boat can be removed directly from the handling unit and placed on the conveyor belt of the system. In another production step, the seat and steering unit is later mounted on the "Personal Water Craft", but without ultrasonic welding. This means that the toy is then packed into the packaging and finally sold in the shops, with the addition of a driver figure. It was also a very interesting project for SONOTRONIC, to which hopefully many more will follow.
On the ultrasonic standard machine, ECO iSONIC in special design hull and lid of the toy boat are welded together absolutely tight.