High throughput rates, long service-lives and effective cutting performance in continuous operation make maximum demands on the materials used for rotary shears in waste incineration plants. Such twin-shaft shredders are used, for example, to prepare domestic and commercial waste prior to thermal valorisation as a secondary fuel. Their cutting tools, exposed to the most adverse conditions, consist of cutter disks with barbed shredder teeth. Dillinger, Europe's leading producer of heavy plate, supplies an extremely wear-resistant steel - DILLIDUR 550 - that sets new standards in this application, too. Harden Machinery Ltd., China's largest manufacturer of size reduction machinery for industrial and municipal waste, has equipped the rotary shear of a large municipal waste incineration plant with this high-performance steel. The plant's cutter disks were produced from DILLIDUR 550 by BMM, the steel stockholding partner for DILLIDUR plate in China. Wear measurements performed at regular intervals during operation indicated a service-life longer by up to 30 percent for the DILLIDUR 550 cutters compared to the DILLIDUR 500 wear-resistant steel previously used.

The cutting tools, exposed to the most adverse conditions, consist of cutter disks with barbed shredder teeth. The cutting tools, exposed to the most adverse conditions, consist of cutter disks with barbed shredder teeth.

Dillinger's highly wear-resistant DILLIDUR special steel has proven its capabilities around the world wherever critical components are subjected to extreme abrasive wear. DILLIDUR, thanks to its special microstructure and hardness, assures up to five-fold greater wear resistance than conventional steels. The steels owes this extreme wear-resistance, with hardnesses ranging from 325 to 550 Brinell, to the sophisticated alloying concepts and special processes used for its production. After rolling, an accelerated and uniform cooling process in the hardening quench imparts to the steel its hard, fine-grained structural state with a homogeneous hardness distribution of the plate. DILLIDUR combines the special resistance to wear thus achieved with good working properties for welding and forming, and low preheat temperatures. With thicknesses of up to 52 millimetres - and an expansion of the portfolio to 100 millimetres planned - plus a hardness of 550 Brinell, DILLIDUR 550 meets customers' wishes for significant increases in service-lives achieved via plates of maximum thickness, weight and wear-resistance.

Continuous service in waste incineration plant

BMM was one of the first users to gain experience with DILLIDUR 550. BMM, with registered offices in Shanghai and two further branches in China, has specialised in the sale and use of these wear-resistant steels since its founding in the year 2000. In addition to the various DILLIDUR grades, the BMM range also includes the high-strength quenched and tempered fine-grained structural steels of the DILLIMAX series. The company's leading know-how in the use of DILLIDUR, acquired in the course of nearly twenty years of experience, makes BMM a highly popular partner for challenging tasks. China's leading manufacturer of shredder systems, Harden Machinery, based in Zhongshan, Guangdong, has thus for years now put its faith in DILLIDUR steels and BMM's proven high production capabilities. For a high-capacity plant for pre-comminution of domestic waste at a waste incineration plant, Harden Machinery commissioned BMM to fabricate a new set of cutters for the twin-shaft shredding mechanism of the rotary shear. The facility operates 16/7 throughout the year, with a daily throughput rate of 500 to 800 tonnes per unit. Continuous comminution reduces the volume of the flow of waste, in order subsequently to permit the extraction of the constituents not suitable for thermal valorisation. Trouble-free operation of the rotary shear is thus the top priority to assure uninterrupted operation of the waste incineration plant, and downtimes caused by cutter fracture or wear are correspondingly feared. Harden Machinery has therefore put its trust in DILLIDUR 500 for many years when selecting the material for the cutters. The cutter disks produced from this material have exhibited service-lives up to now of two to four years, depending on the composition of the feed material. Each of the up to three-metre-long shafts of the twin-shaft shredding mechanism features up to thirty of these cutter disks. These disks, each 50 millimetre thick and 600 millimetre in diameter, contrarotate on the shafts, drawing with their barbed shredder teeth the feed material into the cutting gap, where it is comminuted. The even harder wear-resistant DILLIDUR 550 steel was used for the first time for the new set of cutters at the suggestion of James Meng, founder-owner of BMM. "It goes without saying that a higher-alloyed material has to be worked differently to other steels", James Meng states. For this reason, tests were firstly performed at his company, in order to gain experience with the new grade. He was able here to count on support from Dillingen. He was provided not only with material samples, but also technical documentation and personal support on specific questions. One example here is preheat and insulation of plates for cutting: they are maintained after cutting at the elevated temperature for at least 24 hours by using heat insulation. BMM now uses this specific experience and the documentation from Dillingen to organise seminars for customers wishing to use this material themselves.

Each of the up to three-metre-long shafts of the twinshaft shredding mechanism features up to thirty cutter disks.Each of the up to three-metre-long shafts of the twinshaft shredding mechanism features up to thirty cutter disks.

Service-lives longer by 30 percent

This far-reaching know-how proved its worth once again during the production of the cutters for Harden Machinery's rotary shear. In a first operation, the cutter disks were cut from the plate by means of plasma cutting, in order to minimise internal stresses caused by the input of heat into the material, and thus the danger of cracking. BMM selected the wire-cut EDM process for the detailed cuts. This method permits extremely precise cuts without the generation of internal stresses. BMM's priority during subsequent CNC milling and polishing machining was adherence to tolerances of 10 µm - in processing terms, no problem for this experienced component manufacturer, even with DILLIDUR 550. "Machining time input with this new steel was around five percent higher, and tool wear around a third higher, compared to production of the cutters from DILLIDUR 500", James Meng continues. In his estimation, these extra costs are not in any way significant, in view of the in any case overall high production costs. The new set of cutter disks has now been in use in the rotary shear of the waste incineration plant for 12 months. The plant operator measures wear at regular intervals, in order to be able to estimate the remaining service-life of the cutters. They have more than met his expectations from this highly wear-resistant steel already: cutters fabricated from DILLIDUR 550 convince their users with a significantly greater resistance to wear compared to the service-lives of the DILLIDUR 500 materials previously used. The data measured indicates a service-life longer by 25 to 30 percent for the cutter disks consisting of the even harder material. And James Meng is also correspondingly pleased with this new high-performance steel from Dillinger: "It's only in the nature of things that this more highly alloyed material is much harder and therefore somewhat more difficult to work". He sees no problems in working this steel, however, using modified tools, in some cases, and a modified cutting speed. For James Meng, too, the benefits are immediately apparent: "Thanks to its greater hardness, DILLIDUR 550 assures significantly higher service-lives for components exposed to extreme stresses, and thus even greater customer-satisfaction".

AG der Dillinger Hüttenwerke
For more than 330 years, Dillinger has thrived on its extraordinary passion for steel. Today Dillinger is propelled by a successful product of enormous weight in the most literal sense: steel, from ore to customized heavy plate and ready-to-install elements. A wide range of experience, strong research and development, continuous investments and a networked ability to innovate make the heavy plate manufacturer a global quality and technology leader with steel grades that are for the most part less than ten years old. With these high-performance materials for applications that require extreme load-bearing capacity under the most adverse conditions, the business units for steel construction, mechanical engineering, offshore, offshore wind power, line pipe, construction machinery, mining or pressure vessel construction are among the preferred partners of the best in the industry.

Published inProduction
Thursday, 13 December 2018 15:33

Heavy plates in best form

Dillinger's Heavy Fabrication Division: precision and innovation on a gigantic scale

It takes great skill to keep on coming up with new steel grades and to fabricate them into made-to-measure heavy plates in an unparalleled variety of sizes and thicknesses. This is what makes Dillinger the world leader in terms of heavy steel plate quality and technology. This leading position is founded on its provision of integrated competence in steel under one roof. From steelmaking right through to ready-for-installation high-end products, research, development, steel and rolling mills as well as Dillinger's state-of-the-art plate fabrication facility all go hand in hand. Such a tightly geared value chain guarantees product solutions that precisely meet the challenging demands of the customer and – thanks to their outstanding efficiency, reliability and service-life – perform convincingly, even under extreme operating conditions. Dillinger's more than 330 years of accumulated competence and experience has long since earned the trust of leading companies in the energy branch as well as in the plant engineering and heavy machinery, pressure vessel and steel construction sectors. The fabrication facility at the Dillingen location with its capabilities for further processing of heavy plate offers these customers service à la carte. And whether the customer is after a complete package or a one-off service – if the demand is for "bigger", "heavier", "more precise", "more innovative" or "more efficient" than conventional solutions, the Heavy Fabrication Division represents a significant advantage of partnership with Europe's leading heavy steel plate manufacturer.

Heavy plates with customised preparation of machined welding seams Heavy plates with customised preparation of machined welding seams

A business unit from the very start in one of the world's oldest integrated steel mills, the Heavy Fabrication Division has a unique range of experience. Since its foundation in 1685, Dillinger has constantly expanded its competence across the whole production chain, from steelmaking right through to further processing of heavy steel plate. Today, the Group boasts an annual production output of about two million tonnes of heavy plate in an unparalleled variety of thicknesses and sizes, and in unmatched metallurgical quality. No wonder, then, that this manufacturer is the preferred supplier worldwide for heavy-duty constructions in key industries. The Dillingen location's share in this output is about 1.4 million tonnes a year. Many of the plates manufactured there are also processed in the fabrication facility – some of them even directly as ready-to-install components with thicknesses of up to 430 millimetres.

Excellence in steel

As Dillinger's application-oriented spearhead, the Heavy Fabrication Division is a much sought-after partner for the development and realisation of solutions that already meet tomorrow's demands today. In close collaboration with the customer – and supported by the bundled metallurgical know-how of the steel mill – it consistently achieves excellence in plate fabrication. Its success in this field is founded on continuous further development of processes and production technologies, and also on investment into even more efficient capital equipment. Through its integrated approach to the customer's needs – covering everything from metallurgical concept and steel process route through to fabrication – it keeps on opening up new and often previously unimaginable possibilities. One example of this technological pioneering is Dillinger's response to a challenging customer request for over 210-millimetre-thick racks for the sort of jack-up rigs that are deployed in the offshore sector. Through systematic development, Dillinger succeeded in proving – with an attained thickness of 230 millimetres – not only that this challenge could indeed be met in terms of metallurgical factors, but also that this sophisticated product could be manufactured and fabricated in Dillingen to extremely narrow tolerances and with veritable surgical precision using thermal cutting.

Robot-supported edge preparation on a chord with a wall thickness of 120 mm made of steel grade S690Q mod.Robot-supported edge preparation on a chord with a wall thickness of 120 mm made of steel grade S690Q mod.

The Heavy Fabrication Division's capacity to handle extremely large component dimensions and item weights and to provide innovative manufacturing processes as well as complex welded and formed parts makes it a reliable problem solver for particularly demanding requirements. Its support is just as sought after when limits of production capacity in the customer's supply chain are reached as it is in the development of new potential applications that the heavy plate customer's own capacities can not (yet) handle. Companies exclusively focused on installation operations benefit from the integrated fabrication facility at the steel mill, which offers them made-to-measure complete deliveries from a single source. Dillinger's Heavy Fabrication Division is also the partner of choice for customers dealing with extreme plate dimensions that they cannot further process with their own plant capacities. One of the inestimable advantages for them is the direct access to Dillinger's heavy plate production. Fabrication can then take place immediately without the transportation problems that such customers would otherwise inevitably have to deal with.

Dillinger's welding technology team is at hand for complex flame-cut parts as well as for custom preparation of weld edges. The fact that sophisticated steel grades with thicknesses of up to 430 millimetres and item weights of up to 45 tonnes can be fabricated in Dillingen shows that the facility here is definitely fit for the future. Even if weld preparation calls for flame-cutting or edge machining to an angular accuracy of 0.5 degrees and tolerances of ± 1 millimetre over the full length of a 25,000-millimetre-long plate – just-in-time supply of edge-processed and coded components ensures that Dillinger's Heavy Fabrication Division is a perfectly geared stage in the value chain of, for example, customers in the offshore wind industry.

Hemispherical one-piece vessel head with turned edge Hemispherical one-piece vessel head with turned edge

Formed to perfection

One of the core pieces of equipment in Dillinger's forming technology is a four-roll plate bending machine which delivers a force of 86 MN for the forming of shell plates in a very wide range of dimensions. The machine is capable of cold forming shell sections up to 4,300 millimetres cylindrical length from a 250-millimetre-thick plate – dimensions that most other providers would have to resort to hot forming to achieve. The plate bending machine also excels when it comes to smaller diameters or high-strength steel grades. In the production of shaped and pressed parts, Dillinger sets standards with high-performance forming units, specially developed production technology and custom-built tools. Hot formed heads with wall thicknesses of up to 220 millimetres or diameters over four metres meet the highest demands for dimensional and geometrical accuracy and are therefore a showpiece discipline of Dillinger's Heavy Fabrication Division. Further impressive examples of its leading position are the hot formed quenched and tempered chords up to 130 millimetres thick and 4,550 millimetres long that are supplied in combination with metallurgically identical racks for the offshore industry.

 

Published inProduction