Order numbers on the rise, ever-smaller batch sizes and an increasing variety of articles – to master these challenges, the window and door system manufacturer REHAU in Wittmund, Germany, relies on a state-of-the-art production plant with perfectly coordinated manufacturing and logistics processes. The heart of the internal flow of goods is an automatic UNICOMPACT high-bay warehouse by KASTO. Thanks to this system, REHAU has been able to significantly enhance its order picking performance and flexibility – and make working conditions more ergonomic at the same time.

Doors and windows are essential in all types of buildings, whether they are single-family homes, apartment buildings, public institutions or office & commercial structures. They provide the right light, insulation against heat, cold and sound and protect against wind, weather and uninvited visitors. For private builders as well as commercial and municipal property developers, the selection of optimal windows and doors is therefore an important decision – and they can draw from an enormous variety of different solutions and variants.

REHAU AG + Co. in Wittmund, Germany, knows this topic inside out. For 50 years now, the company has been specialising in window and door systems made of innovative materials. It is part of the REHAU Group, which is internationally active in the processing of polymers. REHAU uses these plastics to produce solutions for the automotive industry, for various other industrial sectors and for window and door construction. The company has more than 170 sites worldwide and employs around 20,000 persons, 550 of whom work in Wittmund.

Organic growth and globally active

REHAU has continuously expanded its plant over the years. For example, a small hall with five production facilities was transformed into a state-of-the-art company complex with a total area of 120,000 square metres. “We supply customers all over the world from here,” explains Ingo Pracht, Supply Chain Manager for Window Solutions at REHAU. “Every day, 30 to 40 loaded trucks leave our premises.” These gigantic dimensions pose very special challenges – and not only for production, but also for logistics within the site.

The raw materials for the window and door systems include profiles made of various plastics, which REHAU manufactures on site, as well as steel and aluminium, which are purchased as merchandise. The 6 to 6.8 metre long profiles are stored in a fully automated high-bay warehouse with space for almost 8,000 items. The 90-metre-long and 25-metre-high system is the heart of the intralogistics of the entire site. The UNICOMPACT storage facility was planned and realised by KASTO Maschinenbau GmbH & Co. KG, which is headquartered in Achern, Baden-Wuerttemberg.

The current trend is towards custom products

“A trend towards more individualisation in the construction industry has been prevalent for some time now,” says Pracht. “For us, this meant more and more orders in ever-decreasing quantities and an increasing range of articles. To supply our customers reliably and quickly, we needed a high storage and order picking capacity; but we soon realised that the storage technology we had simply could not cope with the new requirements.” So REHAU decided to have a completely new storage system installed – in cooperation with KASTO. “KASTO was already known to us as a manufacturer, so we discussed our ideas with them. KASTO’s high vertical range of manufacture, its consulting and planning competence and its flexible response to our individual wishes convinced us immediately,” says Pracht, explaining the reasons behind REHAU’s decision.

The requirements were clearly defined. In addition to providing sufficient space for the growing number of different profiles, the storage facility also had to be highly dynamic to accelerate the picking process. “On average, our employees pick about 100 tonnes of material per day,” reports Pracht. “In the past, two men were needed per picking station and the work was time-consuming and exhausting. Our declared aim was to make this process faster, more efficient and much more ergonomic.” In terms of hardware and software, the new storage facility also had to be seamlessly integrated into REHAU’s production processes.

Dynamic operating devices for the highest possible level of storage performance

Together with the window and door specialist, KASTO conceived a plant with four blocks arranged in parallel. A storage and retrieval machine (SRM) with a portal design is installed in each of the three aisles between the blocks. This layout ensures that each SRM can approach two different blocks, increasing flexibility and speeding up the storage and retrieval processes. With a longitudinal travel speed of up to 240 metres per minute, the SRMs are designed to be particularly dynamic to save even more time. “Each of the three SRMs can handle up to 50 double cycles per hour, so we can process up to 150 positions in one hour,” says Pracht. “That’s a really impressive increase compared to our previous search and retrieval performance.”

The plastic profiles produced on site, plus the steel and aluminium profiles purchased as accessories, are stored in special REHAU long goods pallets for internal transport and dispatch to the customer. However, these pallets are not suitable for conveyor systems, so each high-bay load carrier is forklifted onto a transport pallet supplied by KASTO. These pallets are 7 metres in length and can transport up to 1.2 tonnes of material. There are two laterally arranged storage and retrieval stations per warehouse half, each served by one SRM. KASTO’s own control system – KASTOlogic – takes over the time- and route-optimised management of the storage locations, ensuring that unnecessary journeys and empty runs are avoided wherever possible.

Ergonomic, fast processing of orders

To compile the orders, four picking stations are available for the employees in a separate hall at the front of the warehouse. Each station is equipped with a shuttle wagon and a vacuum-powered lifting device. The required material is automatically retrieved and brought to the desired height. “This eliminates heavy lifting and carrying and the entire process is much more ergonomic,” says Pracht. “The stations can also be easily operated by only one person.” The sequence of orders and materials also determines the warehouse control system, enabling intuitive working and helping to avoid errors.

Picked goods are then temporarily stored in the plant again until they are loaded onto trucks or into containers for shipping. “So the KASTO solution is not really a storage facility for us, it’s an order picking machine,” explains Pracht. The warehouse management software is connected to the higher-level ERP system at REHAU via a specially set up interface – and the KASTO specialists also handled this task. “The interaction at IT level works perfectly,” remarks Pracht. “We benefit from a high level of inventory transparency and the efficient, uniform control of all our intralogistics processes.”

Competent planning and reliable service

The supply chain specialist company is completely satisfied with the entire cooperation with KASTO. “As our main contractor, KASTO took over this project right from the concrete slab stage and brought every aspect of it to fruition, encompassing planning, construction, commissioning and even the training of our staff.” Yet another plus for Pracht is KASTO’s top quality service. “The plant can be serviced remotely, so faults can be remedied promptly with no complications. Spare parts are available at any time and the KASTO technicians are quick to respond when they’re needed.” However, the KASTO specialists have hardly been needed – since the storage system was completed in 2013, it has been running extremely reliably, despite high loads in four-shift operation on at least six days a week.

For REHAU, the new high-bay warehouse was exactly the right solution to make the company fit for the challenges of the future. “We considerably enhanced our picking performance, gained a lot of extra space for material and created more ergonomic working conditions for our employees – and now we can react more flexibly to the increase in orders,” says Ingo Pracht. “The KASTO storage facility is an investment that has already more than paid off for us – and one that we will enjoy for a long time to come.”