WITTMANN MacroPower Injection Moulding Machines Improve AKROH Competitiveness

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 their 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 moulding machine. The occasion is the commissioning of a new MacroPower 2000 from WITTMANN – with 2000-tonne clamping force by far the largest injection moulding 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 moulding, 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 moulding 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 moulding 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 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 in 60 countries worldwide. More than 600 moulds are in active use.

During our visit to Zwolle, large black shovel blades are running off the production line from a MacroPower 850 injection moulding machine. Mounted on a wooden rod with a handle also injection moulded 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 mould 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 consistently high quality”, Arend-Jan Horst emphasises, leading us to another MacroPower machine, which moulds 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 moulding 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 customers. Thanks to the servo C-axis, it is possible to switch flexibly between removal on the moving and the stationary mould mounting platen, depending on the mould.

MeltPro screw and HiQ Flow – a successful duo

Another contribution to the consistently high quality of the injection-moulded parts is made by the plasticising units in the WITTMANN machines. “All of our most recently delivered machines are equipped with MeltPro barrier screws, and we have now also retrofitted the existing machines”, reports Michel van der Motten, Managing Director of WITTMANN BATTENFELD Benelux NV.

By this move, AKROH has prepared itself well for the future, since the proportion of regrind in the materials being processed is rising. When using a machine with a standard 3-zone screw to process materials with a high proportion of regrind, AKROH had to lengthen the plasticising time to achieve sufficiently high melt homogeneity. “This means that for several products we would no longer have been cost-efficient”, Horst explains.

The intelligent assistance systems from the HiQ product series from WITTMANN provide additional support in processing recycled material. The HiQ Flow software measures the viscosity of the plastic melt during the injection phase of each cycle. In the case of deviation from the pre-defined set value, the machine automatically compensates the injection volume within the same shot. The result is 100 per cent good parts.

Especially in recycled plastic materials, the MFI sometimes fluctuates strongly from one batch to the next. “With our WITTMANN machines, we can still process high percentages of recycled material streak-free”, says Horst. “Since our introduction of MeltPro screws and HiQ Flow, we are not getting any more production-related scrap.” Some plant containers are already being produced entirely from recycled materials.  For making the feeding shovels, 10 per cent regrind is currently blended in. This regrind is entirely derived in-house from sprue and start-up scrap.

“Keeping production scrap in the cycle is now an essential strategy for us to remain competitive with our prices”, Arend-Jan Horst emphasises. “For the agricultural products, we have strong competitors in China, India and Pakistan. Here, the unit costs are invariably an important issue.”

Digitalisation secures maximum uptime

“Our customers buy from us because we deliver excellent quality, respond flexibly to customers’ wishes and are nevertheless not more expensive than the Asians”, the manager explains. “The price we are paying for this is a continuous flow of process optimisation.” Consistently high reliability and stability of the machines are not enough. The availability and flexibility of the production systems are also closely examined by the AKROH management for every investment decision.

“When we receive an order today, we can deliver it tomorrow”, this is how Arend-Jan Horst describes the extreme case, which happens quite often. Moulds are changed twice or three times per day, and this must be done quickly to keep the machines’ uptime on top level.

The long-stroke system for releasing the tie-bars supports easy installation of large moulds from one side, and what is more, the progressing digitalisation of the production processes is already showing a positive effect here as well. “The machine recognises the mould by reading out the mould data set and then automatically sets the correct parameters”, explains Horst. “Digitalisation already offers many opportunities today for working even more efficiently. We intend to exploit these opportunities even more effectively in future”.

In family-owned companies, long-term planning is normal

A basic prerequisite for continuous optimisation of processes is transparency. The AKROH team is just starting a relevant project to examine energy efficiency.

“We have set ourselves the task of measuring more. We look at all sources of energy consumption, not only those of the machines. Maybe it is possible after all to turn the temperature of the cooling water up by two degrees in one process or another. The energy prices have risen so sharply in last year that even changes seemingly small at the first glance have a large effect. The important point for me is that we can continue production here in our homeland in spite of the high labor and energy costs – to this end we exploit all opportunities open to us.”

As CEO of a family-owned company, Arend-Jan Horst thinks ahead on a long-term basis. “I was eleven years old when my grandpa bought his first injection moulding machine”, he remembers. “That was a Battenfeld machine, and I learned injection moulding on it.” Strong ties between AKROH and the WITTMANN Group, of which Battenfeld today is a part, have been in existence ever since. “The excellent contacts are important to me”, Horst emphasises. “WITTMANN is a family-owned company like us, and family-owned companies work in a different way. People there talk openly with each other, which also makes it possible to plan the future together.”

Read more from Wittmann Battenfeld here.

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