Automotive supplier Krug geared for new challenges in electric mobility thanks to ENGEL duo

Highly precise, but still cost effective – this was the requirement that Kunststofftechnik Krug posed in its search for a new injection molding machine for the production of fan wheels and frames for automotive cooling systems. Thanks to the ENGEL duo, the company has managed to combine both of these properties under one roof. Good experience gained in production led to ENGEL large machines also being installed at the new technology center at the Breidenbach, Germany, headquarters.

Electric vehicle adoption brings new challenges, such as with radiator fans and frames. Where precision molding of these parts to date has been about ensuring high cooling power, there is now a move towards also focusing on smooth running. Any imbalance in the fan wheels causes vibrations that tend to generate noise. In vehicles with combustion engines, these sounds are drowned out by the engine. But in EVs, even quiet fan noise can be perceived as a nuisance.

“The requirements in terms of quiet fan operation have grown significantly,” explained Rüdiger Braun, managing director of Kunststofftechnik Krug GmbH in Breidenbach, Germany. “Repeatability and dimensional accuracy are now among the most important criteria for injection molding machines.”

Krug is one of the largest manufacturers of passenger car fan systems in Europe.

“For the Porsche Taycan, we now produce radiator fans with a tolerance of 10 grams per millimeter. Not long ago, the specifications for vehicles in this class were 30 to 50 grams per millimeter,” Braun noted.

To manufacture large fan wheels and matching frames, the company uses a duo 900 injection molding machine. The decisive factor for choosing the machine was that the large ENGEL machines combine precise machine movements with very high production efficiency.

Flexibility with high clamp force levels

“We have put in a great amount of development work to further improve the already very smooth action of the fans, and we also took a close look at the injection molding process,” said Jochen Krug, CEO of the automotive supplier.

The challenge was not only to achieve precision in the machine movements but to continue manufacturing in a cost effective and competitive way. The molds were equipped with numerous sensors for the tests. For each individual blade, a pressure and temperature sensor was integrated into the cavity to check repeatability and process stability.

“We’ve seen the duo machines manage to do both things very well,” Krug added.

At the Breidenbach headquarters, the ENGEL duo is now the predominant machine type for the production of large parts.

“ENGEL offers many machine sizes in the high clamping forces range. This ensures a great deal of flexibility for us,” said Braun, “especially since we also purchase plasticizing screws that correspond to our materials.”

The company processes polyamide and polypropylene, which are reinforced with long glass fibers to ensure that the fans are high strength under mechanical stress in continuous operation. ENGEL uses laser technologies to weld on metal carbides in the production of its screws to ensure high abrasion resistance. As a result, ENGEL plasticizing systems achieve a long service life even when processing materials with a high filler content.

Focus on smart assistance systems

Where it may have been possible to balance the large fan models with clamps in the past – much like balancing a car tire – today, the injection molding machine must deliver the precision. Krug invested in visual digitization for quality control. The Atos system by Carl Zeiss Gom Metrology captures a detailed 3D model of the component surface with a resolution of several million measuring points. The focus is on the evenness of the surfaces and the edges – the two critical points when it comes to performance and low noise.

There are plans to additionally leverage the opportunities offered by smart digital assistance in the future. The duo machines are equipped with iQ weight control, which adjusts the injection rate, switchover point and holding pressure in line with the current conditions during each cycle. Fluctuations in raw materials and in ambient conditions can also be automatically compensated for before even a single reject is produced.

“This gives us greater assurance in the series production process,” emphasized plant manager Ingo Heinz.

Krug takes a holistic view of efficiency. High repeatability helps to ensure conservative use of both raw materials and energy. The total energy consumption of the duo machine was analyzed before the purchase decision was made.

Standardized machine control

Krug supports its customers throughout their products’ life cycle. From product development and simulation, through mold making to series production, assembly and logistics. Many customers opt for the complete package, while some choose specific value generation stages.

“We have some customers who only want to perform sample inspection for one mold,” Braun reported.

To avoid the need to block production capacity for this, Krug is building its own mold technology center. An initial machine has already moved in. As has a duo 900.

“It is important to us to have the same machines in the technology center as in production,” said Rüdiger Braun. “Having standardized machine control units makes things easier for our team.”

One difference to production, however, is immediately apparent: the technology center has its own color scheme, and the machines there are orange instead of ENGEL green.

Under the Innotec umbrella, Krug is continuing to expand its range of services for all aspects of molds at the new technology center. Demand from customers is increasing.

"We are very experienced in injection molding and as a mold maker which is another advantage for our customers,” as Krug emphasized.

Getting more out of the machine

“We are increasingly moving towards multi-stage processes of value creation,” said Jochen Krug, describing an important trend.

The integration of assembly steps into the injection molding process, along with multi-component processes for the production of hybrid parts have arrived at Krug. For example, in the Household Products business unit. At its Breidenbach location, Krug produces housings and complete assemblies for Thomas brand vacuum cleaners and vacuum washers with strict requirements in terms of the surface quality.

“Combining a high level of vertical integration with automation allows us to keep producing parts like this in Germany,” said Rüdiger Braun.

The third prerequisite is good partners, people who also offer great support in after sales.

“What we have seen is that we really get more out of the machine with the consultancy and training that ENGEL offers around processing engineering, allowing us to achieve truly top quality,” said Jochen Krug.

For more information, visit engelglobal.com.