For the 100 per cent quality check, Maier has installed a camera system right next to the assembly station. The robot must move the part only 20 centimeters to the right. Here, the W832 pro robot’s rotary servo axes play out their strengths, for they are required to present in quick succession three different critical points on the molded part to the camera. First comes the silicone membrane just mounted. It is checked whether the membrane has been fitted correctly and whether the holes below it - each only 1 mm in diameter - are all open. At this point, the LED camera installed on the gripper comes on in order to take perfect pictures for evaluation. After checking the ventilation valve, the robot turns the part to give the camera a clear view onto the TPE seal. The camera focuses precisely on the part of the seal which penetrates most deeply into the hard component. "If this part is completely filled, the rest of the seal is also faultless", says Fabio D’Amato, COO of Maier. Finally, the connector coding is checked. If the image processing system signals OK three times, the W832 pro then deposits the fuse box on the clockout belt and immediately picks up a new set of inserts for the next cycle.
Real-time communication across corporate boundaries
To enable an extremely fast changeover from one fuse box model to another, there are not 18 different molds, but instead several different mold inserts and grippers. A particularly large amount of coordination work has been invested in the grippers. Where to place the valves? How to guide the energy chain so that the end-of-arm tooling can turn the part in the shortest possible time? And how to save weight? The Wittmann team had really looked into every detail and fully exploited all efficiency potentials.
The lighter the robot arm, the more scope is available for the weight of the gripper and the parts to be moved. What is more, light weight has a direct positive effect on energy efficiency - a topic particularly close to the heart of the decision-makers at Reinert They are pleased to find the Wittmann linear robot equipped with a sustainable feature. Thanks to EcoMode, the robot varies the speed of its movements. The injection molding machine sets the clock with its cycle time. The robot fully utilizes this time window, which means that most of the time it moves more slowly than technically feasible. This saves energy and simultaneously protects the mechanism in the interest of a long service life for the robot.
To provide communication between all components of the production cell - including the injection molding machine, the two robots, the assembly station and the image processing system, all coming from different manufacturers and each equipped with their own control systems - they are interconnected via Profinet. This industrial Ethernet standard laid out for realtime communication ensures a smooth process and facilitates the production startup following machine setting. Before the central control unit of the automation cell starts the production process, it checks whether the correct program has been set on the injection molding machine and on the linear robot. The network system also enables fast remote servicing in the event of a malfunction. The specialist engineers from Maier can access the cell from outside, to check the control system of all individual components and to view the camera images from quality assurance. "Wittmann is the ideal integration partner", says D’Amato. "Not all robots offer so much flexibility and openness."
Easy operation is vital
Wittmann was already well known to Reinert long before the fuse box project got under way. Many more Wittmann robots are operating on the production floor in Bissingen, and products from Wittmann are also in use at the two other plants of Reinert in Czechia and Romania. "Our production staff members are top fit as well as familiar with programming and operating the robots from Wittmann", says Klement. "This is mainly due to the easy operation and continuity in operating logic across many generations of robots."
At the beginning of the project, an articulated robot for the tasks of insertion, removal, assembly and quality checks was briefly considered. But Reinert deliberately decided against this option. "I have always said that things should be kept as simple as possible", explains Jürgen Hahn. "That minimizes the error risk, and our machine operators are very keen and highly motivated." The Managing Director is also familiar with the further advantages of Wittmann: "The robots are sturdy and long-lasting; we are getting excellent service."
Geared for growth
In close teamwork, Reinert, Maier and Wittmann have trimmed the automation of the entire process for maximum efficiency and flexibility. Every detail was analyzed in order to meet all requirements and still keep the costs reasonable. Programmers and software experts from Wittmann were also on board. "Whenever something has to be reprogrammed, it took just a telephone call, and the work could go on at once", says D’Amato.
The production cell is laid out to produce up to 400,000 assemblies per year. In the preseries, 50,000 fuse boxes for agricultural utility vehicles are being produced to begin with. How fast the numbers of units may increase is not foreseeable. For a start, the production cell is to be fully utilized with other, equally complex parts. "The basic concept of the production cell keeps all options open for us", says Christoph Klement. As soon as the fuse boxes really take off, the trays now being filled manually can very easily be replaced by vibrating bowls, hoppers and separators. Then the equipment will be able to maintain autonomous production for up to eight hours.
