Tailwind for innovation

Special plant manufacturer Hedrich vacuum casts rotor blades for wind turbines. The company relies on control and automation technology from Siemens for improved product quality.
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Success in all markets

Innovation leaders know that an inspiring, valuable idea is required for success. The Hedrich Group has developed a process with which rotor blades for wind turbines can be vacuum cast completely for the first time, significantly improving product quality – and SIMATIC S7-1200 plays a key role.

As the technology leader in vacuum plant manufacturing for electrical applications, the company headquartered in Ehringshausen, Germany, exports more than 90% of its products and is active on almost all continents. The unparalleled experts tirelessly take on new challenges in order to meet individual customer requirements. A few years ago, the growth potential of the wind power market became apparent and they developed an innovative, fully automatic vacuum infusion process especially for casting rotor blades.

“We can completely prevent air and gas inclusions that occur with the conventional method, since the entire process takes place under vacuum,” says Peter Rektorschek, Head of Digital Solutions at Hedrich. “This increases the structural strength of the end product and eliminates costly finishing work to remove remaining cavities.” Their success speaks for itself. “Within just four years, the plant established itself so rapidly on the market that it now accounts for almost 20% of our sales,” notes Marketing Director Sascha Kandler.


Full automation in the vacuum

First, the raw material (resin and hardener) that is drawn in from intermediate bulk (IB) containers used for the transport and storage of liquid or free-flowing materials is conditioned, degassed, and dehumidified under vacuum in a mixing plant on a fully automatic basis with SIMATIC ET 200SP as the head controller. 

The conditioned material is pumped into a ring line up to 500 meters long, which contains up to eight modular infusion stations for several rotor blade half shells. These so-called Infucubes are each automated with a SIMATIC S7-1200, which is connected to the head controller and communicates with it via TCP/IP.

“Thanks to SIMATIC S7-1200 with CPU 1214C, each Infucube operates independently,” explains Rektorschek. “It has valves with appropriate sensors and a softbag set under vacuum as a material buffer that rests on a scale and holds a maximum of 10 kilograms. The half-shell draws the material out of it until it is filled.” Both the sensors and the scale are connected to the controller. Its task is to switch the valves and thus request the material until the first filling is complete and then do so again for a certain residual quantity from the main controller. The main controller stops the process as soon as the mold can no longer accept any more material. It also takes note of the weight of the bag thanks to the scale connected in the same way. Then the operator starts the next Infucube. “Once the half-shell of a rotor blade is filled, it takes about 24 hours to harden, after which it can be shaped or bonded to a second half-shell,” says Rektorschek.

Thanks to SIMATIC S7-1200, project engineering time can be shortened by up to 70%.
Peter Rektorschek, Head of Digital Solutions at Hedrich

In the first variants of the system, the infusion stations did not yet work with their own controller. There was only the head controller of the mixing plant with decentralized I/Os. “Among other things, the disadvantage was that we could only check the functionality of the infusion stations in conjunction with the running head controller. Now we can distribute the monitoring capacities much better,” says Rektorschek. In addition, the number of connected infusion stations had to be known and taken into account during project engineering. “Today we work with a single program version for the main and secondary controllers and only need to adjust the parameters for each plant, shortening the project engineering time by up to 70%.

This allows the customer to easily add more Infucubes to their system or replace defective stations during the process, reducing downtime and increasing availability. They then parameterize them using their central controller and the SIMATIC KTP400 Basic Panel on the new Infucube. This shows the operator all relevant status information and process data. They can also enter how full the bag is to be filled towards the end of the process in order to reduce waste, for example.


Standards that span plants and controllers

There were good reasons for choosing SIMATIC S7-1200 to control the Infucubes: Hedrich uses SIMATIC S7-1500 for larger plants in all areas of the company – Siemens' controllers are widely used throughout the company.

“Both controller families can be programmed using TIA Portal, and almost every program module can be swapped between the controllers as required,” explains Rektorschek. “This has allowed me to create standards that we can reuse on both controller platforms. If you also include the onboard peripherals, SIMATIC S7-1200 is even more cost-effective than a decentralized ‘dumb’ solution.”

Siemens has been a valued partner to the specialists for many years. “Some 70% of our controllers now come from Siemens, along with almost all of our control cabinet equipment, especially since their acceptance among customers is very high,” says Kandler. In addition to the technology, he and Rektorschek are convinced by the support and the price-performance ratio, especially since the rollout of TIA Portal. “The easy accessibility of the controllers via remote maintenance is also an important point for us. It is also possible to connect the plants to the IoT operating system MindSphere with ease.”

Further tasks for SIMATIC S7-1200 are already in the works. For one, Rektorschek wants to include this controller in standard modules such as the vacuum pump set in all Hedrich plants.

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