Author: Georg Schöpf, x-technik FERTIGUNGSTECHNIK

Automotive suppliers have the challenge of complying with the ever-increasing demands of the OEMs. Large batch sizes of components need to be delivered, just in time, with reproduceable, ever-higher quality. Lightweight construction is of increasing importance and, therefore, so is the manufacture of bigger, lightweight structural components made from aluminum and magnesium.

GF Casting Solutions Altenmarkt GmbH & Co. KG is a premium supplier for this kind of part. The firm was founded in Austria in 1972, under the name Alucon, and later was operated by Mössner Druckguss. It has been part of GF Corporation since 1999. For over 20 years, the firm has focused on manufacturing components for automotive production. Product and process development for high-pressure die-cast components is one of its specialties. »We are constantly facing the challenge of manufacturing bigger and bigger components. To keep the weight of the components as low as possible, you end up with die cast parts with low wall thickness, which creates its own challenges for high-pressure die-casting and manufacture,« explains Reinhold Brunnthaler, Senior Expert for Mechanical Machining at GF Casting Solutions. Over the years, the experts in high-pressure die-casting, from Styria, Austria, have expanded their knowledge and expertise for the necessary process steps. Now, they're in the position to offer the entire value chain, from simulation to high-pressure die-casting to mechanical machining and part coating, as well as checking for efficiency, and seamlessly documenting the entire process.

High level of in-house production
»Our services cover all process steps right up to ready-to-mount components, and we have all the necessary machining methods in-house. Cutting plays an important role in this. Our fleet of machines comprises almost 50 machining centers. With high-pressure die-cast machines with closing forces of up to 4,400 t, we machine nearly 14,000 t of aluminum and magnesium per year and each part requires some form of post-processing«, Brunnthaler justifies the high capacity requirements.

Customized solutions
The CHIRON DZ 25 P twin-spindle machining center, which was first put into operation in February 2020, has a development story that fits perfectly with the process development objective of the GF Casting Solutions site. Dirk Schmid, Head of technical Sales Germany, Austria, Switzerland at the CHIRON Group SE, remembers »We've been working with Georg Fischer for over ten years now. There are more than 15 machines of the CHIRON Group working at the site in Herzogenburg and in Altenmarkt. We knew that the requirements for batch sizes and the dimension of the parts were constantly increasing. Because we wanted to support customers like GF to work more efficiently, we asked GF in 2015, whether they were interested in helping us develop a highly productive, twin-spindle machining center.«

The aim was to develop a manufacturing system precisely tailored to the needs of automotive suppliers for machining structural components. »We compiled a feature list with a precise profile of requirements for a new, twin-spindle machine concept. Of course, we started from the necessary machining steps, but we also rethought the composition of the machine from scratch. A shuttle table concept for equipping the machine during operation, as well as a quick tool changer for reduced change times. We also had to keep in mind the high safety requirements,« Brunnthaler goes into detail about the design.

 Prioritizing stability and ergonomics
The main focus was on highly productive machining of complex structural components. This was one of the reasons that the CHIRON Group opted for mobile gantry design for the new development, rather than the tried-and-tested a traveling column design. »The result was an extraordinarily stable and rigid machining center which also fulfills all our wishes in terms of precision. We found out precisely which factors are relevant for cycle times and focused on those in particular. It became clear that tool changing and workpiece positioning were crucial aspects for this,« Schmid says. The turntables, mounted in parallel on the bridge of the A-axis with an 800 mm spindle distance, can be fitted on the loading space and swiveled in. Both HS motor spindles run on independent Z-guides, enabling mirror machining and compensation of possible component distortion.

Capacity for high productivity
The significant rigidity of the machine allows high dynamics and very fast axis acceleration, as well as fast rapid traverse speeds. Two separate tool magazines with space for 60 tools each, offer independent tool change on each spindle for short Chip-to-Chip times of 3.5 s. With axes of 800 x 1,100 x 800 mm (X/Y/Z), it's easy to machine large parts and the spindle torque of 200 Nm at 20,000 rpm is transferred safely to the tool via a HSK-A63 interface. The new TouchLine operating panel is based on a Siemens 840 D sl.

»The positive experiences with CHIRON machining centers allowed us to win GF Casting Solutions Altenmarkt as a development partner for the new structural component machine. The previous machines are, for the most part, also universal. The DZ 25 P is one of the newest developments from the CHIRON Group, ideal for structural components for the automotive industry. It's a true workhorse in terms of performance, productivity and reliability,« Dirk Schmid looks satisfied as he finishes his explanation. Reinhold Brunnthaler adds, »Our cooperation with the CHIRON Group was really very fruitful. We regularly refined the details together with developers until the set-up was thoroughly perfect. During the installation test phase we actually produced suspension struts for Audi and then immediately moved to three-shift operation. This helps us achieve the current rates of around 270 parts per shift; which is a huge increase in productivity compared to the old system.«

The CHIRON Group also offers a solution for larger structural components now, with the DZ 25 P in one size bigger. The new 28 Series with 1,200 mm spindle distance perfectly complements the CHIRON Group portfolio. Based on the same machine platform, the new CHIRON series are precisely designed for the various workpiece dimensions, covering the whole range of sizes and complex components for automotive and aerospace applications.