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Name:
Dirostahl - Karl Diederichs KG

Address:
Luckhauser Straße 1-5
42899
Remscheid
Germany

Phone:
+49 2191 593-0

E-mail:
info@dirostahl.de

WWW:
www.dirostahl.com

Company management:
Dr. Manfred Diederichs | Executive Head

German firm Dirostahl specialises in the production of open-die forgings of 10kg to 35,000kg, seamless rolled rings with an outside diameter of up to 3.500mm and forged bars of up to 15m long, all in alloyed and unalloyed steel grades. The company’s main expertise is in producing short-run customized pieces that are applied across numerous industries and applications. Most topically, Dirostahl’s forgings are used in wind turbine gearboxes, and can be found in industrial printing presses and production machinery used in the automobile and shipbuilding trades.

There really are endless applications for open-die forgings, but Dirostahl’s edge is when it comes to meeting clients’ very specific, and often fairly limited, requirements. The company has recently upgraded a number of its facilities to further enhance this key selling point, as Dr. Diederichs describes: “We’ve lately made some improvements to how we produce our large forged rings. We have a new press capable of 3000 tonnes’ pressure. This is used to form the raw pieces that are then milled into the rings, but because the ring mill is 10–12m higher than where the next production step takes place we had to install a specialised automated lift to carry the hot rings, which at this stage are at 1000ºC. This new lift, which is quite possibly the only of its kind in the world, transports the rings down to where they are then taken through a series of cooling and reheating treatments. It is here that our ability to produce short runs of varying pieces is demonstrated. We utilise robots capable of carrying pieces of up to 2 tonnes and that can recognise the differing dimensions and specifications of each piece. The varying qualities of the metal are achieved by precisely modifying the temperatures during these stages. So, each piece is heated and then cooled, to precision. This cooling is done by submerging each piece in a ‘bath’, which rather than water actually contains a kind of ‘liquid plastic’. We have 16 of these baths so at any one time we can modify the temperature and programming of each bath to therefore produce pieces to meet 16 different and specific requirements. This enables us to efficiently produce runs of only 30 or 40 pieces at a time, while ensuring the highest quality of each.”

Meticulous quality control

Dirostahl has a long tradition of going above and beyond to ensure the quality of its products and customer service. Again, recent developments to the firm’s facilities have improved Dirostahl’s capability in this already-sound area. “We operate two main halls side-by-side; one holds all items ready for dispatch and the other is where we undertake all the quality testing. Our examination process is unique and advanced; we run a kind of production line to carry out all our testing in one place. We first take the piece through an ultrasonic inspection, which involves putting a gel-like substance on the metal so it can scan properly (the gel acts to remove any air between the metal and scanner which will interfere with the reading). Once the piece has proven to be ‘good’ that same gel has to then be removed, and this is done by passing the piece through a small furnace, heating it to 200ºC. From here the dimensions of the piece are digitally measured and recorded and a further machine tests the elements present in the steel, to ensure they precisely match those required by the client. The entire testing setup is enormous and extremely thorough, and every one of our pieces is taken through each testing stage. This means that our clients can be sure that we supply metal pieces that meet their requirements exactly, every time.”

Automated dispatch

Once each item has passed through the quality-control process it is loaded on to a wooden pallet ready for dispatch. This sounds fairly standard, but again Dirostahl has employed the latest technology to ensure the process runs as smoothly as possible. “Our warehouse is 21 metres high and holds 2,860 pallets arranged over six aisles. Each pallet can hold up to 2 tonnes, so that’s around 6,000 tonnes of finished material waiting for dispatch at any one time. The warehouse is completely automated – it’s strictly a no-go zone for staff! The storing and collection of orders is all managed digitally; the dimensions of each item are sensed and logged so that the most appropriate location can be found to store it, making effective use of the space. Data relating to each pallet’s content and location can be very complex, and because we fulfil such varied orders (with differing dimensions and weights) it’s a very precise operation. To fulfil an order, whoever comes to collect the item simply has to present its assigned five-figure code, which is then scanned to enable the item to be located and retrieved automatically by machine.”

The improvements continue for Dirostahl as later this year will see its workshop used for the production of long metal pieces undergo a complete refit that will take it from housing three to seven machines. Evidently, even after 400 years Dirostahl steel continues to go from strength to strength.

Gabrielle Brown

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