Metal fabrication on the path to the IoT

Under the umbrella of SMS Holding GmbH, the SMS group is a group of international companies devoted to systems and machine building for the steel and non-ferrous metal industry. The business units include continuous casting plants and rolling mills, as well as equipment for steelworks, and tube and pipe and forging technology. Over 14,000 employees worldwide generate sales of around 3.4 billion euros.

SMS initiated its strategic project for complete modernisation of production even long before the term the Internet of Things (IoT) reached the ears of the public. The goals are a sustained increase in productivity and shortening of delivery times as well as long-term job security at its Mönchengladbach plant. Behind these objectives is an investment volume of over 60 million euros. In addition to modernising the infrastructure, well over half of this investment was in highly modern equipment for producing system components for the heavy machines that SMS builds. In just over three years’ time, all the machines were replaced with a new pool of machines — all without interrupting production. Today, boring mills, a double boring mill with two operator’s platforms, gantry machines, vertical lathes and flatbed lathes with up to 21 m of travel are producing complex parts made of tempered steel weighing up to 200 t. These are generally one-off parts or small series of maximum 10 pieces, which often run many hours or even weeks on a machine without interruption.

“We are taking a variety of small and larger steps on the path to the IoT,” said Alexander Goebels, head of production planning at the Mönchengladbach plant. One of these steps is greater flexibility in production, which is to say production planning with respect to flexible machine utilisation. Overall tool management based on tool identification using Tool-ID from Balluff is a key component in the new organisation and automation concept.

“Our tool management is today neither economically justifiable without the RFID data carriers, nor is it conceivable for reasons of process reliability with respect to error prevention such as incorrect matching, or typing mistakes when manually entering tool parameters,” added Judith Schmitt, plant manager for mechanical production.

“All the machines are incorporated into an integrated framework organisation with central NC programming in the work preparation and decentralised PC stations for production data acquisition and NC program simulation using EXAPT,” explained Schmitt. In addition, a host production controller computes the greatest possible machine utilisation. Also part of the overall system is a central tool presetter that supplies all the machines.

Tools are provided to the machining centres for the most part fully automatically, such as in the heart of production with four machining centres and an associated high-bay warehouse for the workpiece pallet automation system.

“On average, the machining time for components in this production area is two hours per fixture, with often 70 to 80 different tools required,” added Goebels. A particular highlight of the high-bay warehouses is the integrated shuttle system for fully automatic supplying of the machining centres with tools. The prepared tools are brought to intermediate storage stations/provision areas at the machining centres. From there a second shuttle takes the individual tools and delivers them in a manner synchronised with the movement of the respective platform machine, so that the tool handler of the machine can take the tools on the fly during the main work phase. The tools are returned in the same manner. Goebels notes that in this area alone, including the 120 magazine slots in the four machines, around 1000 actively job-specific tools are circulating.

“In the entire plant we manage around 10,000 technologically and geometrically different tools, each of which is available either singly or if needed as multiples,” added Peter Sosnitzka, who is responsible for the tool setters. In his area all the tool components are maintained and in general all tools prepared. Here the relevant tool parameters are sent to the Balluff RFID data carriers without contact at the same time they are measured. The data is passed along to the EXAPT tool and production management program, which handles the entire process chain from tool identification to management to actual production use. The system ensures consistent processes, greater transparency and all-in-all increased production efficiency. The Tool-ID system from Balluff further ensures that all the required tool data including the tool life written back on the machines is available, correct and up to date, at every place the tools are used. This reliability and the errorless electronic data transmission via RFID read/write heads at all the transfer locations and machines is especially valuable in the production areas where tools are manually transferred. This can be the case in tool magazines on machines or in coupled magazine systems where additional industrial robots handle the tools.

“But nowhere is there a path around a read/write head from Balluff,” emphasised Sosnitzka.

Valued even much more than the time savings and the greater flexibility is the security of the infallible data association for every tool provided by the fixed RFID data carrier and the errorless transfer of the parameters when tools are changed.

“Even the slightest keyboarding mistake can have fatal consequences — even including a crash,” noted Schmitt, who can hardly dare to think about the machine downtimes, much less possible damage to the expensive components. An equally important advantage of Tool-ID from Balluff is the optimal service life resulting for the tools. Even if the savings potential at SMS cannot be exactly quantified, continuous checks and writing back the run durations to the data carrier ensure that timely regrinding or replacing of indexable inserts or tools is ensured, thereby preventing premature discarding. This reduces tool costs and allows the inventory to be kept in exact proportion to needs. All in all, these are many reasons why Tool-ID is also used cross-plant, in other words group-wide at SMS.

“The tool identification system from Balluff contributes in many ways to sustained increase in productivity and shortened delivery times,” said Goebels, who sees the overall halving of delivery times as achieving the goals of the modernisation project.