Highly automated injection moulding with impressive complexity

The company has a workforce of around 555 – including 215 robots – and operates 114 injection moulding machines that produce over 1.3 billion parts annually. Martin Weißer, who heads the company in the third generation with ambitious plans for the future, is in charge of overall operations: “Together with our customers, we want to develop groundbreaking manufacturing solutions with a high degree of functional integration and set standards according to our motto ‘Excellence in plastic’. The new production line for the radomes clearly shows the direction in which we are thinking.”

Picture: While a Yaskawa GP25 fills the intermediate storage in front of the injection moulding machine, the larger GP50 assumes its loading and unloading tasks.

Time-optimised development in simultaneous engineering

Even before the series order was placed, W+G technicians were closely involved in the development process at automotive supplier Bosch. At the same time, the first stations for the automation of the injection moulding cell were built at special plant manufacturer EGS Automation in nearby Donaueschingen. “Due to the tight time budget, we had to start planning the automation in the middle of product development, i.e. without final data. Nevertheless, we managed to set up a rough plan by designing certain plant components and processes very flexibly and paying attention to easy replacement and adaptation,” says Hartmut Pfalzgraf, Project Manager at EGS Automation.

Working in simultaneous engineering played a decisive role in ensuring that the complex production line with the two linked injection moulding processes could be put into operation in a timely manner. And this is how the manufacturing process is configured: the plastic base units with two contact pins will be produced by the first injection moulding cell, equipped with a punching line, a Scara robot for isolating and placing the contacts, a Yaskawa six-axis robot for loading and unloading the Arburg injection moulding machine, and a testing station. Here, the base units undergo a 100 percent check before being placed in trays and stacked by a Sumo Ecoplex tray stacker from EGS Automation.

Picture: Hundred percent transparency - a large display panel visualises the data of each process step of the production line.

An injection moulding cell that is second to none

From here it goes in manual operation directly to injection moulding cell 2, where the operator feeds the trays equipped with base units to the plant via a second Ecoplex palletizing system. As Martin Weißer proudly announces: “Together with our proven plant manufacturer EGS Automation we have succeeded in automating a complex manufacturing process with many upstream and downstream work steps within a very small space. This fully automated injection moulding cell demonstrates what is feasible today with its total of six robots, a winding station, five integrated test stations, multiple sensors and impressive manufacturing IT.”

The high level of functional integration here becomes clear when we look at the processes: First, the base unit must be wrapped with a hair-fine copper wire, to be used later to heat the radome. This is performed by a special winding system that also welds the wire ends to the pins and carries out an electrical continuity test. A Scara robot automates this cell. The next step involves overmoulding the wire-wrapped base unit. This two-stage process is carried out by an all-electric Arburg 920-2K injection moulding machine. Sophisticated testing processes follow before the radomes are provided with a data matrix code.

Picture: Reaching into the injection moulding machine - the GP50 while loading and unloading.

Reliable six-axis robot with high dynamics and precision

The facility is so complex that only a few employees understand and master it down to the last detail. One of them is Emre Yeniay, Technical Engineer Manufacturing Equipment at W+G: “The interlinking of all stations of the plant is fully automated with five Yaskawa six-axis robots, including two GP25s for handling tasks, a large GP50 for the automation of the injection moulding machine and two GP7s that operate the downstream testing processes. To ensure the most gentle handling of the radomes, all robots are equipped with vacuum grippers. Besides high precision, the Yaskawa robots score top marks with optimum availability, crucial for our 24/7 operation.”

One of the most prominent features of the facility is the large transfer station situated in front of the injection moulding machine and accessed by the two GP25s and large GP50. The smaller six-axis robot takes over the assembly of the base units coming from the winding system; the larger GP50 picks them up in pairs and inserts them into the SGM. The transfer station is generously dimensioned with a capacity of 24 base units. Emre Yeniay explains why this is necessary: “This station is also used for buffering. If there is a malfunction in the upstream process during wire winding, the injection moulding machine can continue producing within the cycle time. The keyword here is thermal equilibrium, which gives our technicians the critical time to fix the problem.”

Picture: A compact Yaskawa GP7 six-axis robot during the complex radar attenuation test.

Highly developed test procedures with absolute transparency

After overmoulding, the GP50 removes the parts from the SGM and immediately performs the first test step. In a swash circle inspection, the robot moves the parts under a camera system that checks the exact alignment of the contact pins. The GP50 then feeds the parts to a second transfer station. This is where the journey of the radomes through further test stations begins. Parts handling is carried out by two compact but precise Yaskawa GP7. First, an electrical resistance test is carried out to determine the correct function of the heating wire, and a flatness test is performed in the tolerance range of only ten micrometres. A complex radar attenuation test is then carried out.

Finally, a GP7 six-axis robot transfers the parts to a laser labelling station, where the tested radomes receive their individual data matrix code, which is then checked for readability in the next step. All information regarding manufacturing and QA parameters is stored in this DMC code, ensuring 100% documentation and traceability of each component. In the final step, the GP7 inserts the radomes into the customer SLCs, which are then stacked by a GP25 by another Ecoplex palletizing system after they have been fully fitted and manually removed from the system.

Picture: At the laser labelling station, the tested radomes receive their individual data matrix code.

AI should further minimize error rates

The reject rate plays a crucial role in the manufacturing costs of the safety-relevant component. Martin Weißer: “In order to keep the error rate as low as possible, we must have the best possible command of the process. The radomes are relatively expensive components, and each reject part compromises our profitability. Therefore, each manufacturing and testing step is monitored by sensors and the data is visualized on the system by a DAQ system on the prominently placed display. We follow every process in real time, identify trends and can immediately take countermeasures.”

But that is not enough for the corporate leader who strives for perfection. To further optimize the processes, Weißer + Grießhaber employs manufacturing IT specialists whose task is to implement additional AI skills. The basis for this is already available in the form of existing data volumes from each process. “With the use of generative AI, we want to move from a reactive to a forward-looking manufacturing model that also has the intelligence to optimize itself. The result will be a further reduction in the error rate in the near future,” says Weißer.

Picture: Final handling step: a Yaskawa six-axis GP25 hands over the loaded SLC to an Ecoplex palletizer system.

Acting with foresight, pursuing visions, developing technologies – these are precisely the issues with which Martin Weißer is concerned. “We must expand our technological pioneering role; that is the only way to secure Germany as a production location. In the medium term, we will therefore position our company as an assembly and process solution provider with its own development expertise, and pursue this path together with innovative partners such as EGS Automation. The production of the radomes with the two linked injection moulding processes with a high depth of value creation, the multitude of integrated processes and high-tech automation shows where the journey is headed,” Weißer concludes.

Picture: CEO Martin Weißer, W+G automation experts Emre Yeniay and Hartmut Pfalzgraf, Project Managers at EGS were able to put the ambitious project goals into practice.

Text: Ralf Högel 

Pictures: ©Yaskawa Europe GmbH