AE Plast Kft. trusts tie-bar-less ENGEL victory combi machines

As a plastics processor in the technical molding sector, AE Plast Kft. in Hungary needs one thing more than anything else: maximum flexibility. Especially since the applications are very challenging. Multi-component injection molding processes are part of daily business. To combine precision with efficiency here, AE Plast relies on injection molding machines from ENGEL. The victory model range's tie-bar-less clamping units were the deciding factor.

AE Plast in Császártöltés in southern Hungary was founded in 2006 as a joint venture with the aim of supplying customers in the white goods and power tools sectors with parts that comply with strict requirements. Robert Bosch Power Tools is just as much a part of the customer base as Bosch Siemens Household Appliances, and also many automotive suppliers. "We are not the classic contract injection molder, but contribute a huge amount of expertise to customer projects ourselves and also help to develop the injection molds," as Managing Director Thomas Herpertz emphasizes. "We have earned a very good reputation due to this." AE Plast produces for global markets.

For example, the housing components for the multifunctional MM20V rotary tool for cutting, grinding and milling are intended for the US market. AE Plast will deliver 80,000 assemblies to Dremel this year. The assembly consists of a cup housing that holds the rotary head in the finished product, and two half-shells that form the handle and enclose the battery.

"The most important thing is stability," says Herpertz, describing his customer's requirements for injection molded parts. "The Dremel housing needs to pass the drop test from a height of two meters without damage." Other relevant factors include an attractive design and great ergonomics in the rough and tumble of everyday construction site use.

The three-component design equally meets all of these requirements. The gray basic part is made of polyamide with a glass fiber content of 35 percent to ensure stability. The black areas are made of TPE to ensure a good grip. The blue stripes are trim parts that are also made of glass-fiber-reinforced polyamide to achieve an optimum bond between the two thermo-plastic components.

An ENGEL victory combi injection molding machine with a clamping force of 400 tonnes, a vertical rotary table, three injection units and an integrated ENGEL viper linear robot are used for production. The assembly relies on two molds: a 2-cavity mold for the cup housing and a 2+2-cavity mold for the two half shells. "The cup housing is the most challenging part," as Szabolcs Balla, project manager at AE Plast explains. "We need a large core with jaws in the mold here. The blue trim strips are then injected on via gate valves. The mechanics with a total of ten gate valves mean that we need a 27-zone hot runner." The different shot weights are a further challenge for the victory machine. 120 grams of gray PA per shot are processed for the basic housings, while the blue component has a total shot weight of just 5 grams, and the TPE component needs 20 grams of raw material per shot. Highly precise process control, and the excellent platen parallelism and uniform clamping force distribution of the tie-bar-less clamping unit ensure great repeatability here.

The special feature of this injection molding process is that the three components are processed in just two injection molding steps. The two gray base components are produced in the first step. At the second position of the rotary table, the blue PA and the black TPE are injected at the same time. To make this possible, the design was configured to avoid the blue and black areas of the part touching at any point. "This helps us boost production efficiency," says Balla.

While the basic part design was specified by the customer, AE Plast carried out extensive DFM analyses and mold fill analyses in-house to design the injection molding process. "Where do we inject, how do we separate, and how do we still keep the mold sealed while injecting the low-viscosity TPE? These were the questions on the table, and in each case we had to keep an eye on the shrinkage of the individual components," Balla reports.

The Corona pandemic added a further challenge: coordination between the customer in the USA and the moldmaker in Asia was all handled virtually. "Traveling was impossible at the time," Herpertz explains. "We had to rely on sample inspection in Asia. Test tools were used to simulate how the three components could be processed in the most efficient way."

In 2008, the first of today's total of eight ENGEL victory machines was installed at the AE Plast production plant. The decisive factor was tie-bar-less technology, which is still a unique selling point of Austrian injection molding machine manufacturer ENGEL. Unobstructed access to the mold area speeds up mold setup and, by doing so, boosts machine availability, especially if there are many mold changes, which is the typical case for contract injection molders. While Dremel parts have very long running times, the molds on other machines at the plant are set up frequently. Two mold changes occur in each shift on average. In line with this, the efficiency potential that the tie-bar-less machines leverage in three-shift operation during a five-day week is huge. And the production floor height, which is comparatively low at five meters is an important factor. "If we had injection molding machines with tie bars, we would have to remove a tie bar to set up the molds," as plant manager Gábor Frémer points out.

The automation also benefits from barrier-free access to the mold area. The robot arm can reach the cavities directly from the side without having to circumvent any obstacles. This reduces the overall cycle time in some applications.

Other aspects contribute to the flexibility of the machinery, in particular the customizations that ENGEL has implemented for its customer. "We can vary the nozzle distance of the injection units between 160 and 300 mm, making it very easy to mount a wide variety of customer molds," Frémer is pleased to report. "ENGEL implemented this for us very quickly and with no trouble at all." ENGEL also adapted the hole patterns on the mold fixing platens and the ejector bores to the individual requirements of AE Plast.

Another benefit: From the start of the cooperation in 2008, the control unit of the ENGEL injection molding machines was in the Hungarian language at no extra charge. "With other injection molding machine suppliers, this was still an expensive custom option at the time," Herpertz reports. "We can toggle between German and Hungarian in the control interface. This is a huge advantage for us as we train many employees ourselves."

There is no such thing as an apprenticeship plastics molding in Hungary. When it comes to on-the-job training, AE Plast receives great support from ENGEL-HUNGÁRIA Kft, the ENGEL sales and service subsidiary in Budapest. "We have access to training in employees' native language, which is a big help," says Herpertz, emphasizing the very good personal contacts across the board and the short distances: "We can clearly see that ENGEL is a family business. We can talk to each in an open way and reach out to each other. We handle many things without any red tape. That's our understanding of collaboration."

AE Plast is planning for the future with ENGEL. The topic of sustainability is high on the agenda. Much has already happened here, and the two partners also tackle new challenges together.

For example, energy efficiency is becoming significantly more important. "Some of our customers are already carbon-neutral, and they expect their suppliers to continuously improve in this respect, too," as Frémer points out. "Injection molding machines are major energy consumers, which is why we take a very close look here and also capture the long-term trends. If we compare the first machines delivered in 2008 with the latest victory machines to be delivered, we see energy savings of 25 percent on average."

The state-of-the-art servo-hydraulic system, ecodrive – which has been included as standard equipment with the ENGEL victory for some time now – also makes a major contribution towards this. While the machine is at a, for example during cooling, the motors are idle. Energy loss is avoided in this way. The cup housings for the Dremel tools offer particularly high potential for saving energy. The cooling time accounts for almost half of the total cycle time of 52 seconds.

"Processing recycled material is also a factor in increasing numbers of new projects," as Herpertz reports. "Grinding in sprues has lost its bad reputation. For each product, we evaluate with our customer whether recycled material can be added and, if so, how much."

With a very high level of in-house plasticizing expertise, innovative processing technologies and digital smart assistance, ENGEL supports its customers on their path to a circular economy. As a system solution provider, ENGEL ensures that all system components, technologies and the digitization concept are matched in the best possible way. "The everything from a single source strategy makes things very easy for us, from project planning through commissioning to after-sales service," as Herpertz points out. "No matter where an issue crops up, we simply call ENGEL and get help very quickly."