Kontron eSystems, a supplier of IoT-capable AC wall boxes, has expanded its injection molding capacity at its Leipzig site by starting up five new production cells delivered as integrated solutions by Wittmann. Two of the new cells are equipped with automatic IMD lines. According to the company, the investment combines production efficiency with design flexibility, which is important for housings manufactured to the requirements of individual automotive OEMs.
The start-up is also linked to a change in the sourcing model for plastic parts. As Lars Böhme, Manager of Plastics Operations at Kontron’s Leipzig plant, points out, many components, especially larger ones, had previously been purchased from an external contractor. The acquisition of a new customer led to a change in this strategy and to the largest injection molding project at the site in more than 30 years. A key element of the investment is automated, highly integrated injection molding lines planned and delivered from a single source.
One example of the manufactured products is wall box housings consisting of eight injection-molded parts in total. The front cover carries the vehicle brand, and after installation the logo is intended to be backlit. Requirements for the housings include resistance to weathering and reliable long-term functionality, both under severe frost and under direct sunlight. In addition, scratch resistance is important because RFID or NFC cards are held against the surface and often wiped across it, and contact with rings or keys can damage the outer layer.
IMD for visible and functional surfaces
To combine functionality with design requirements and surface durability while enabling product variants, Kontron decided to manufacture the front covers using an IMD (in-mold decoration) process. According to the company, decorating visible and functional surfaces with a film is usually more efficient, flexible and robust than painting parts after injection molding.
Together with partner company Leonhard Kurz, a capacitive film system was developed that contains the complete electronic operating system. This made it possible to design a closed user interface without additional control panels or switches mounted on top. Multi-layer film systems were used, which also makes it easier to integrate backlit design elements such as the vehicle logo. As stated in the source material, the IMD process is intended to give product designers broad creative scope while maintaining competitive unit costs.
MacroPower, sequential injection and dynamic temperature control
The second largest component among the wall box’s eight parts, after the basic housing weighing 2 kg, is the front cover. Depending on the variant, shot weights range from 500 to 800 g, and production takes place on a MacroPower injection molding machine. Single-frame decorations are fed in a roll-to-roll system onto the clamping unit. Once the decoration is positioned correctly, the injection molding machine’s control system receives a signal from the film feeding system and initiates mold closing. The processed material is crystal-clear polycarbonate because the entire decoration, including its color scheme, is generated via the film.
Due to the size of the covers and the requirements for a smooth visible surface, sequential injection molding (cascade process) is used. This approach is intended to fill the cavity as evenly as possible with the plastic melt, reducing the risk of visible weld lines. “The film is highly sensitive. Even the smallest unevenness shows up even more distinctively in the decoration of the film,” Böhme explains. In this context, attention is drawn to the accuracy of the MacroPower machine movements and to the dynamics of the Tempro plus D temperature controllers. As indicated, fast cooling affects part quality and at the same time supports cost efficiency, and the cycle time remains below one minute despite the high shot weights.
A multi-axis robot removes the finished cover from the mold while a new decor frame is simultaneously fed into the cavity.
Automation and integration of third-party systems
After demolding, the cover is transported to quality inspection and then directly to packaging. The only manual operation is the visual inspection required by the OEMs. All other tasks are carried out by Wittmann linear robots, including stacking parts in transport boxes. A camera integrated in the robot gripper ensures correct positioning, enabling fully automatic packaging. Within the cycle, the robot deposits the molded parts and also places the interlayers.
As soon as boxes are completely filled, they are removed by autonomous transport systems, which simultaneously replace them with empty boxes. The entire automation system, including the control connection to the existing autonomous transport equipment and the box changer, was developed by Wittmann automation specialists at the Nuremberg site. When designing the movement sequences, the focus was on maximizing overall system efficiency.
Linear robots were selected for quality inspection and packaging, while a multi-axis robot is used for demolding. As Maximilian Töpfl, Production Manager at Wittmann Battenfeld Deutschland, explains, this was required by the limited hall height and the dust-free enclosure system. “In this particular arrangement, the multi-axis robot helps us above all to save space at the top,” says Töpfl. “We have developed this multi-axis robot in-house and integrated it seamlessly into the overall system. This is another of Wittmann’s strengths: the ability to adapt flexibly to customer needs and on-site conditions.”
Clean room enclosure and reduced changeover times
The injection molding cell is enclosed as a clean room area because even dust particles would become visible under the film decoration. A laminar flow box installed above the clamping unit generates a downward air flow, capturing airborne particles and pushing them out of the working area.
A challenge during planning was the exchange of IMD rolls and the need to open and enter the clean room enclosure for this operation. “The roll weighs 30 kilograms and has to be lifted to the top of the machine. But we have no room here for a conventional platform,” explains Ludwig Pander, responsible for plastics technology and assembly at Kontron eSystems. “Wittmann came up with a brilliant idea here, which was very easy for us to implement.” The concept uses the space behind the clamping unit to install a small platform integrated into the machine, allowing the operator to climb up to install the roll after it has been positioned by the indoor crane.
To reduce setup time, another customized solution was implemented that allows the laminar flow box to be pushed back easily across the entire top of the system. “With this solution, we save a lot of time. The roll change takes us only half an hour, not half a day as is usual for conventional systems,” says Pander.
Start-up under time pressure and single-source supply
“With this investment in process-integrated and automatic production lines, we have created an ultra-modern, competitive manufacturing system for making technologically sophisticated visible parts,” summarizes Stefan Salesch, Automotive Sales and Marketing Manager at Kontron eSystems. It was also noted that the schedule was demanding: the new customer set the production start date, and planning, installation and start-up of the first equipment components had to be completed in less than six months while ongoing orders continued to be processed. This meant that the new systems were installed in parallel with the dismantling of existing equipment.
“The time schedule was the most critical part of the project,” confirms Töpfl. He also points to supply chain effects still being felt at the time and to the need to retrospectively increase the clamping forces of two injection molding machines that had already been ordered, because the final decision on the wall boxes was made only very late in the process. As a result, the complete facility layout and the originally planned positioning of the equipment inside the confined production hall had to be reviewed. “We almost had to cut open the wall of the hall. We had less than five centimeters of space left. That was real high-precision work made to measure. Here, the space-saving design of our machines was a real help,” Töpfl reports.
Kontron negotiated the project with several suppliers. “Wittmann offered us the shortest go-to-production time and has actually delivered on schedule,” says Pander. Töpfl attributes this primarily to Wittmann assuming overall responsibility as a system supplier. “We did not have to wait for external partners, but could finish everything in-house in Nuremberg, which saved us a lot of time.”
The deciding factor was said to be the ability to supply everything from a single source, including the injection molding machine, temperature control, material handling and automation. “After all, we did not only need the injection molding machines, but the equipment around them as well. So, we relied completely on Wittmann’s expertise,” says Salesch, adding: “We are very proud of this completely newly designed injection molding production. It has triggered a spirit of optimism at this location. The colleagues here can see that we are going further ahead.”
Central granulate conveying system
Kontron eSystems’ Leipzig site is linked to a long production history largely shaped by Siemens. A total of 30 million business telephones were produced here for global markets, combining electronics manufacturing with plastics expertise. Kontron benefits from this legacy also because some former Siemens staff are still employed at the site. “IMD technology was already introduced here in 2003,” Salesch reports, referring to decorative strips for telephone housings produced at that time.
Today, wall boxes account for about 50% of Kontron eSystems’ sales in Leipzig, while the other half comes from contract manufacturing. “We are optimally positioned for technologically sophisticated visible parts with shot weights ranging from 20 grams to two kilograms,” says Salesch. In contract manufacturing, many customers come from the automotive and e-mobility sectors, and the electronics industry is also increasingly relying on Kontron’s production capacities in Leipzig.
As the product portfolio continues to diversify, the range of materials processed in the redesigned injection molding hall is also increasing. Therefore, following the successful start-up of the new lines, Kontron initiated another project, a large central material supply system from Wittmann, which now supplies all machines with granulate.
