German steel stockholder Weser Stahl, based in Stuhr-Brinkum, has extensively automated its operation to meet increasing competition from international suppliers.

The key element of its in-house logistics is a recently installed storage, sawing and robotic handling system supplied by Kasto Maschinenbau, represented in the UK by Milton Keynes-based subsidiary Kasto Ltd.

It provides unattended material flow through the facility, from storage of the raw stock to provision of the sawn sections for shipment. For Weser Stahl it means greater efficiency, higher productivity and more ergonomic working conditions. The installation has proved so successful that another automated warehouse is being planned for Weser Stahl's site in Plettenberg.

More than 2,500 standard grades of steel are in use throughout the world, from simple construction steel to special alloys, and they are available in a wide range of dimensions and geometries, making the steel trade very challenging.

Companies that want to succeed in the increasingly competitive international market must be able to supply their customers promptly with the materials they need, cut exactly to their requirements.

Weser Stahl has specialised for many years in the sale of hot-rolled and forged-steel bars, steel tubes and bright steel. Production, testing and distribution are combined under one roof at the owner-managed company, which delivers mainly to customers in northern Germany and Scandinavia. It sells about 30,000 tonnes of the 250,000 tonnes delivered by the Westfälische Stahlgesellschaft group, of which it is a member.

Increased customisation
More than half of the items shipped are cut to size, a proportion that is rising, as managing director Dr Markus Krummenerl pointed out: “Our customers are outsourcing more and more machining processes. For this reason we have been continually expanding our capacity in this area.

“It has led to increasing customisation. Our order numbers have been rising while batch sizes have been shrinking. This of course poses a big challenge to us in manufacturing and logistics.”

Weser Stahl relies on modern machinery and equipment to meet this challenge. It has a number of bandsaws and circular saws supplied over many years by Kasto. Dr Krummenerl added: “We particularly appreciate Kasto’s ability to provide solutions, even when we have special requirements.”

It was the main reason behind Weser Stahl’s decision to engage the sawing and storage equipment manufacturer when it decided to launch an ambitious project to automate the provisioning of the saws so that they could run largely unattended, enabling Weser Stahl to handle the increasing numbers of orders and meet the growing customer demand for part-finished products.

Dr Krummenerl continued: “Another important aspect for us was safety in the working environment. We wanted to make our employees’ activities more ergonomic and their daily tasks easier to prevent accidents and injuries.”

Previously, material had been transferred to the saws by an overhead crane – a laborious and not entirely hazard-free procedure involving bars and tubes weighing a tonne or more. After detailed calculations, Kasto determined that the optimal system to replace this process would be a fully automatic, cantilever arm storage system.

Weser Stahl opted for a KASTOcenter Varioplus 4. Measuring almost 8m in height, the system provides 1,398 storage spaces for material up to 7m in length. The compartments have a usable loading height of 50 to 430 mm and each can take a maximum of four tonnes of material.

Bar is handled by a storage and retrieval machine (SRM) that moves at speeds of up to 60m/min. Two KASTOvariospeed circular saws, also automatic, and one KASTOtec bandsaw are connected to the storage facility.

The stockholder holds about 20% of its inventory in the storage system. Sales manager Stieven Harder explained: “We know what kinds of pre-cut parts are most frequently requested and we give preference in storage to these materials.”

Bar stock is usually delivered by truck in bundles that are unloaded, unpacked and placed in storage via a transport cart. Selection of a suitable storage location is handled by the KASTOlogic warehouse management system, which optimises SRM travel to minimise access times.

Greater transparency
Mr Harder further advised that to protect against rust there are separate storage areas for bright steel and rolled steel and the rules for this segregation are also contained in the software. The KASTOlogic is connected via a special interface to Weser Stahl’s higher-level ERP system, ensuring greater transparency and simplifying the communication of order data.

Material removed from storage is conveyed via roller tracks to whichever saw has been assigned to fulfil the job. A handover station in front of the saw serves as an additional buffer to avoid waiting times.

The two KASTOvariospeed circular saws each have a cutting capacity of up to 150mm, while the KASTOtec FC 4 bandsaw is suitable for larger material up to 430mm in diameter. The latter saw was in use before the storage system was built. Kasto simply integrated it into the new system and added the two circular saws.

Weser Stahl also relies on automation for the removal of material. The KASTOtec saw is equipped with a turning and stacking system and the two KASTOvariospeed saws each have an industrial robot that automatically removes sawn sections and stacks them onto pallets, as required for each order.

The automated peripheral systems including robot integration were also implemented by Kasto. Mechanically, electrically and in terms of software they are perfectly matched to the automatic sawing machines and storage system.

Mr Harder said: “In this way, we have created a continuous material flow that can function fully unattended if necessary – and around the clock. The result is an enormous increase in efficiency and performance, as well as more ergonomic working conditions for our employees.”

Remnants are returned to storage by the conveyer system and SRM. The latter has been specially reconfigured so that it can carry not just one bar, but several at a time.

In Dr Krummenerl's opinion, it is a good example of how well Kasto responds to the special needs of its customers. He said: “Whether it involves custom-manufactured equipment or service after commissioning, we know we are in good hands.”

Weser Stahl and Kasto have further plans for automation. They intend to introduce a Jungheinrich driverless transport system to connect the saws and remove pallets with stacked cut parts from the working area of the KASTOsort robot and take them to the dispatch warehouse.

Kasto has already created the necessary peripheral equipment, such as the protective enclosures for the saws with a roller gate and optical sensors for trouble-free entry and exit by the automated guided vehicles.