Moulds Production 5-axis machines deliver precise 3D contour of blow moulds — overnight and during the weekend
Blow moulds produced by Blomix are used worldwide. The Dutch company strives to meet highest quality demands while remaining flexible and economical. The recent investment in automated 5-axis machining centres from Hermle helps the company achieve these goals.
Mould manufacturer Blomix designs, engineers, manufactures and maintains moulds for extrusion blow moulding in the southern Dutch town of Brunssum, about 30 kilometres north of the German town of Aachen. These moulds are subsequently used with thermoplastics to produce bottles, jerrycans, drums and pressure tanks for fruit juices, shampoo and household cleaners as well as petrochemical and medical substances. Their volume ranges from 20 mm to 500 litres — although precision, not size, is the real challenge. Since a blow mould always consists of several parts, for example to integrate cooling ducts or to create complex shapes. To ensure seams or burrs are not visible on the finished blow moulded products, Blomix machines the transitions to guarantee a precise fit. “For the perfect 3D contour, we manufacture with tolerances in the range of a few microns,” Beenders explains.
Although this might sound very simple, it is technically very difficult to achieve: The moulds spend up to 15 hours on the machine in just one setup — enough time for thermophysical properties such as thermal conductivity to negatively impact the perfect end result. To prevent this from happening, Blomix has had an ultra-modern, extra-high workshop built. The nine-metre-high ceiling and adiabatic cooling based on evaporative air cooling help to keep temperature fluctuations to a minimum down on the shop floor. The second safeguard is the actual machinery: Three 5-axis machining centres from Maschinenfabrik Berthold Hermle.
It all started back in 2007 with a C 30 U. When Luuk Beenders became Managing Director of Blomix in 2014, he introduced a new strategy: His aim was to make the company more flexible and innovative while further improving quality. The C 30 U tied in well with this concept and he decided to invest once again in Hermle: 2018 and 2020 saw the arrival of a C 400 U and a C 650 U respectively. “We needed a machining centre on which we can process up to one-metre-long blanks,” Beenders says when explaining his decision in favour of the C 650 U, which replaced a somewhat outdated machine.
Precision speeds up installation
The milling centres from Gosheim are characterised by their precision and long-term accuracy. This is ensured not only by their rigid construction in a modified gantry design but also by their integrated compensation of thermal expansion. An investment that pays for itself: “The outstanding precision of the Hermle milling centres helps to cut installation time. The individual components fit together much better, thus reducing the time spent reworking,” Beenders claims.
A look inside the light and bright production facility shows yet another reason why the decision was made in favour of Hermle: The reliable automation solution. “This is the only way we can remain competitive,” the Managing Director explains. It is important that the machine and the automation come from the same source, as this increases ease of use and technical availability. “If problems arise, it's quite clear who's responsible. In addition, the team at Hermle responds very quickly when we need its help.” While a robot changes the pallets on the C 30 U, Beenders opted for the HS flex system, which was launched in 2017, for the other two 5-axis milling centres and explains: “We needed a solution that could flexibly address varying workpiece dimensions and automatically handle blanks and workpieces clamped on pallets. When we ordered the C 400 U, the HS flex automation that Hermle had launched the previous year was therefore our favourite.” The fact that the C 650 can now also be automated with an equally flexible system was an important factor when it came to making the final decision.
We're one of the first companies in Europe to use the HS flex heavy system and it's going very well.
Introduction of the HS flex heavy system in March 2020 therefore came at just the right time for Blomix. The rotary, lifting and linear axes of the automation variant for the workpieces weighing up to 1200 kilograms move and place the pallets precisely between the machining table, shelf and set-up station. Blomix currently uses ten pallets — although there is actually space for twelve — which is quite sufficient for the time being in view of the long runtimes.
Uniform operation ensured
Even though the HS flex heavy system is new, the team at Blomix found it easy to operate right from the start: Like the flexible handling system of the C 400 U, the heavy variant is controlled and managed by the Hermle Automation Control System (HACS). Hermle has developed the intelligent order management solution specifically to make access to the milling machine and automation as efficient, convenient and intuitive as possible. To stop his engineers from working on the disused machine out of old habit, Beenders resorted to using a somewhat unusual but extremely effective object — a padlock. “I would've handed over the key in exchange for a plausible explanation. But to this day it's remained untouched in my drawer.”
Beenders is delighted with the integrated operating concept of the machining centres: “In our case, flexibility doesn't just mean we can easily swap parts between the three Hermle machines, it also means operators are proficient on each machine.” They can thus optimise machine utilisation, thereby ensuring greater capacity. Room for improvement is important at the company, which works in a project-based manner. “We don't utilise the machines to maximum effect as this allows us to respond more spontaneously to requests from customers. Nevertheless, it has to worth our while,” the Managing Director explains. His goal is to make the best possible use of automation and thus increase profitability. During the day, workers complete the complex tasks, perform tests and prepare the unmanned shifts. At night and on weekends, the 5-axis machining centres ideally run autonomously.
“We don't want to be the biggest, but we want to remain the best,” Beenders explains. “We achieve this goal through our adherence to deadlines and high-quality standards. And we can only do this with partners like Hermle, which keeps its promises in terms of precision, reliability and service.” Nevertheless, Beenders still hesitated briefly before purchasing the C 650 U. The reason for this was the tool length. “The maximum length possible at present is 350 mm. For some geometries, however, we occasionally need tools measuring up to 500 mm in length, which can only be inserted manually.” Fortunately, this was the only thing he had to compromise on with regard to the C 650 U the Managing Director admits. “Overall, we're extremely satisfied.” Beenders is now planning to introduce new ERP software and improve how the machines are interlinked. And he knows for sure that: If a new machine is required, only an automated one comes into the equation.