Reproducibility and flexibility on a large scale

MacroPower injection molding machines from WITTMANN achieve high competitiveness

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Not far from the Ijsselmeer in the north of the Netherlands, AKROH Industries B.V. manufactures a wide range of plastics products for many different branches, including agriculture, the automotive industry and healthcare. The MacroPower from WITTMANN is one of the most popular machine models on its production floor and plays a key role in the company’s growth strategy.

AKROH is celebrating. On the day of our visit, three cream cakes were delivered to the production plant in the Dutch city of Zwolle, each decorated with a photo of a WITTMANN injection molding machine. The occasion is the commissioning of a new MacroPower 2000 from WITTMANN – with 2000 t clamping force by far the largest injection molding machine ever installed at AKROH. With this investment, the family-owned company is opening a new chapter in its history. Following the massive expansion of its machinery, further growth is now planned for the business segment of contract injection molding, which currently generates about 20 per cent of the company’s sales. “We are continuously stepping up the product portfolio for our customers”, states Arend-Jan Horst, owner and CEO of AKROH Industries B.V.

With 27 injection molding machines in a wide range of clamping forces, the company’s machinery and equipment has almost doubled since it moved into its new building three years ago. “We are now a modern factory”, says Horst not without pride, since his whole family is contributing to the company’s success. His wife Olga and his son Jorn, for instance, are in charge of the accounts department. Jorn’s brother Robbert is responsible as operator for the injection molding machines of the plant.

Ultimate reproducibility for extremely tough products
Since the company’s foundation in 1956, its product range has been changed and diversified several times. Among AKROH’s own product lines, one main focus lies on agricultural applications. Equipment for livestock and dairy farming as well as tractor components have made the AKROH brand famous especially in Europe. Via the agricultural trade, the company currently delivers more than 7,000 different products and product variants into 60 countries worldwide. More than 600 molds are in active use.
During our visit in Zwolle, large black shovel blades are running off the production line from a MacroPower 850 injection molding machine. Mounted on a wooden rod with a handle also injection molded from plastic, they will be sold as feeding shovels later on.

These large parts with a 1,000 g shot weight are produced in a single-cavity mold within a cycle time of 30 seconds. They are made of high-impact polypropylene, for they must be able to withstand some tough treatment during rough daily use in the stables and on the fields. Between summer and winter, the environmental temperatures may vary from -10 to +40° Celsius, which must not have any adverse effect on the stability of the shovels.

“With the MacroPower we can rely on producing consistent high quality”, Arend-Jan Horst emphasizes, leading us to another MacroPower machine, which molds large plant containers to a customer’s order. “Here, the requirements are even more stringent”, he explains. “The wall thickness is no more than 1.5 mm, yet we still achieve very high dimensional accuracy.” This was not the case with an injection molding machine of a Chinese brand, which AKROH purchased some years ago on trial. Especially with thin-walled parts, which require high injection pressures, the Chinese machine’s sensor system quickly reached its limits.
Another advantage of the MacroPower in direct comparison between the machines is its modest floor space requirement. Thanks to two-platen technology, the MacroPower’s footprint is noticeably shorter.

Generally, the footprint of the production cells is a major issue. Even when it comes to automation, AKROH ensures a compact layout. A conscious decision was made to equip the new large 2000-ton machine with a linear robot. In contrast to a six-axis robot, which would take up additional floor space next to the machine, the WX173 linear robot from WITTMANN is mounted directly on the machine above the clamping unit. For maximum flexibility during parts removal, WITTMANN integrated two additional servo rotary axes for its customer. Thanks to the servo C-axis, it is possible to switch flexibly between removal on the moving and on the stationary mold mounting platen, depending on the mold.