Process time and footprint halved

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Process time and footprint halved

Planetary gear carrier machining in just two clamping positions

Two Heckert 5-axis horizontal machining centres connected to a robot cell are used to produce process-intensive planetary gear carriers. Setup times are hardly significant, and the automated pallet, gripper and tool handling as well as the intelligent choreography of the individual machining steps ensure the shortest possible process and throughput times. Voith benefits from a high level of precision, efficiency and process reliability, which enables the company to increase its productivity, reduce unit, tool and equipment costs and save production space. No other manufacturing solution on the market currently offers such a deep level of process integration.

Check out the benefits

How do you manufacture twelve different components of a planetary gear in two clamping positions each and simultaneously reduce machining time, production area and parts costs?
Starrag shows in this video the solution of that task.

Step 1 – Machining time @ 0:25
Step 2 – Tooling and fixture costs @ 1:14
Step 3 – Required production area @ 1:55

State-of-the-art power-transmission machines serve as the automated gearboxes. They consist of a large number of interlocking components
that can be driven by force and torque. There is a wide range of different types, and vehicle manufacturers require maximum performance and robustness in addition to low weight. Finally, the gearboxes must feature exceptionally smooth running and extremely little friction loss.

Gear manufacturers must be able to deliver different variants in changing quantities to the assembly line of the automotive companies at exactly the right time. This places high demands on manufacturing plants, processes and logistics. In 2018, gear manufacturer Voith signed off on the construction of a plant for the automated production of planetary gear carriers. The requirements set out in the specifications were very demanding: With an annual production of several thousand parts, multiple different component variants would need to be produced flexibly with only two clamping positions. It goes without saying that the requirements for precision, fault tolerance and process reliability were also high. “At first, this seemed to us to be quite radical, and at first glance it looked difficult to accomplish with the standard technologies and procedures,” recalls lead Project Engineer Matthias Gündel. “But with a good amount of engineering expertise, a development mentality and a close cooperation with Voith, we were able to take on this challenging project.”

The requirements set out in a specification can usually be implemented in different ways – but not all solutions are ultimately productive or even efficient. This is exactly where creative engineering knowledge and decades of experience in technology and processes come in to play. For years, Starrag has enjoyed an excellent reputation as a manufacturer of highly productive horizontal machining centres for cutting, turning and drilling workpieces. Chemnitz-based Heckert machines provide the leading solution for processing cubic workpieces, especially for applications in the transport industry, wind energy or precision machine construction.

Friedrich Oberländer, Director Production Technology at Voith

“Highly integrated production steps and fully automatic conversion are unique features for this plant.”

Starrag engineers and designers, together with Mittweida-based automation specialist SAV, enthusiastically set out to develop a unique production plant. “It quickly became clear that our proven Heckert T45 machining centre would be able to meet the existing requirements for turning, cutting and drilling. But the particular challenge was to develop automated, time-saving solutions for preparation and setup in combination with clever process handling,” says Gündel.

In fact, the planning and implementation phase was a teaching and learning project for all involved. “Highly integrated production steps and fully automatic conversion are unique features for this plant. Ultimately, this was only possible through close cooperation between all parties involved across all stages of the project, from conception to the installation of the production plant in our facility,” says Friedrich Oberländer, Director Production Technology at Voith in Heidenheim. The automated handling, logistics and production solution consists of two compact Heckert T45 5-axis horizontal machining centres and an integrated robot cell. The robot effectively functions as a master and orchestrates the entire automated processing plant, checking the incoming components and loading or unloading the two processing centres. Identical or differing type variants can be machined. The extremely short process and throughput times are partly thanks to the robot automatically setting up the required grippers and type-specific pallets during the main machining time. When the operator approves a new series for production via the HMI, the robot changes all equipment within just eight seconds. The required gripper and pallet applications are pre-assembled and ready to be picked up in the robot cell storage system.

“With this innovative production solution, we are able to halve the previous process time. While the plant is processing the component on both sides in less than ten minutes, the robot uses the bulk of this time to prepare the next workpiece,” emphasises Application Engineer Nico Lämmel proudly, who programmed the essential parts and finally set the plant in motion.

As the change from machine to machine and the associated re-clamping, installation of clamping devices, tools and sometimes even part cleaning processes that are typical in standard production are no longer necessary, the total throughput time is also drastically reduced. The chosen production solution offers an optimal flow of parts and therefore a small work in process (WIP) inventory. Intermediate storage of the components on dedicated free surfaces is therefore no longer necessary. “We know from experience that, depending on the organisation of process logistics and intralogistics, the production of a component series can take a long time until it is ready for assembly. With the new plant, we have been able to achieve this demonstrably faster,” says Nico Lämmel.

The extent to which users benefit from additional advantages can be seen by directly comparing the previous process and the new, integrated production process from Starrag: “Assuming an annual output of 50,000 parts per year, this plant is not only allowing us to cut the process time in half, but – depending on the application – the user can increase their productivity per unit area by up to two and a half times, reduce tool costs by around a quarter and reduce equipment costs by 50%,” said Marketing Manager Christian Queens. “It’s not every day that you get so many USPs from one product!”

A closer look at the actual machining process demonstrates why the chosen production solution offers maximum precision and reliability: Once the component is clamped, an optimally co-ordinated sequence of roughing, smoothing, turning, spindle, cutting and drilling operations begins with fast start-up and deceleration rates. The magazine features 60 tools for various tasks, some of which can change from internal to external processing in less than one second. There are also multitools with various lathe tools, which eliminate the need for tool changes. “The Heckert T45 handles all machining tasks with an extremely high level of precision. The central element is a powerful rotary table with a maximum speed of 900 rpm, which replaces the multiple lathes used in the standard process. Thanks to the HSK T100 tool holder and five axes, Starrag is the only company to offer a horizontal machining centre that can combine clamping hydraulics with mill turning,” explains Nico Lämmel. The integrated process sequence clearly shows how Starrag is able to transform demanding requirements into innovative solutions.

Voith was already impressed with the efficiency, performance and speed of the system during the initial demo run. The highly innovative production solution is proof that standard turned parts do not have to be manufactured exclusively on lathes. “The special feature of the plant is that the unproductive setup process is carried out during the main machining centre time, which drastically reduces the throughput time. With this optimised and flexible design, we are able to manufacture different components in multiple variants and respond directly to customer requirements,” summarises Friedrich Oberländer. An intelligent solution that is sure to attract interest in the automotive industry and beyond.