Ian Melin-Jones

Ian Melin-Jones

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.

Mills CNC is a business quite literally at the cutting-edge of engineering technology. As the exclusive distributor of Doosan machine tools in the UK and Ireland, the company supplies over 450 new machines a year to the market from an extensive range of hi-tech cutting equipment, covering everything from CNC lathes and turning centres to horizontal boring machines and multi-axis mill-turn centres.

These are technologically advanced machines used by many of the leading OEMs in the aerospace, automotive and specialist engineering sectors for the precision manufacture of engineering components and parts.

Being extremely sophisticated pieces of kit they are high value items, costing anything from £50,000 for a small lathe, right up to £600,000+ at the top of the range. The machines are also very heavy and can often be of huge proportions – units may weight up to 55 tonnes and can measure 5m deep and up to 10m long. Therefore, handling such heavy and valuable loads with great care calls for substantial lifting power, with precision control.

Although the heaviest of machine tools can only be moved by crane, the vast majority of units are within the carrying capacity of a really heavyweight forklift truck – but only the biggest and best of counterbalance trucks could do the job.

Until recently the business used an old 16 tonne counterbalance truck for manoeuvring smaller lathes and machine tools at its Leamington Spa showroom and workshop facilities. However, after 20 years service it was becoming unreliable, costly to maintain and could only handle 50 per cent of the product range. Hiring in suitable forklift trucks to cover for downtime and specialist cranes to move the larger, heavier machine tools was becoming an unwelcome expense and an administrative inconvenience.

Realising the need to substantially upgrade its handling capabilities, Mills CNC turned to the forklift truck division of its close business associates, Doosan Industrial Vehicles, and after a review of options, entered into a ten-year lease and full maintenance arrangement on a Doosan DV250S-7 twenty-five tonne counterbalance forklift truck – the giant of Doosan’s comprehensive truck range.

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“Our machine tools weigh quite a lot. Even the smallest lathes are a few tonnes,” says Andy Knight, Finance Director at Mills CNC. “That’s why we needed such a large forklift truck to move them around our site and to position them carefully when unloading and loading lorries. It made perfect sense for us to go for the biggest forklift truck available.”

Emphasising the importance of an on-site handling capability of up to 25 tonnes, he says: “Having reliability, coupled with the availability to lift and manoeuvre our machines whenever we need to, is a real benefit to our business. Now, with this 25 tonne Doosan truck we have the ability to lift and move 95 per cent of our products. Our record, to date, is lifting a 21.3 tonne heavy-duty vertical milling machine – so we are now self-reliant and have the flexibility we need to respond quickly, without having the inconvenience, delay and added cost of routinely hiring specialist lifting equipment.”

A major consideration for the business was the precision required when lifting and positioning their finely engineered machine tools. With machines capable of cutting to the micron level a mere jolt could affect the calibration and cutting performance of the machine tool.

However, Andy Knight was reassured by the smooth handling characteristics designed into Doosan’s DV250S-7 heavyweight truck. Together with a comfortable driving position, power steering and load-sensing hydraulics, Doosan’s powerful low-emission engine provides high torque at low revs, reducing fuel consumption and ensuring accuracy and gentle handling.

“One of the great attractions of the Doosan truck was that just about everything you might want was included as part of the standard specification – including fork positioners, load-sensors and power steering,” explains Andy Knight. “The guys are very happy with the truck too, they like the heated seat and the easy handling of the vehicle – and it’s performing really well.”

He adds, “As you’d expect from Doosan, we got a great deal.”

Doosan Industrial Vehicle is one of the world’s leading manufacturers of forklift trucks.  A complete product range of more than 200 models from the smallest hand pallet truck to the giant 25-tonne diesel trucks all offering maximum durability, reliability and ease of use.

Doosan’s UK head office is based in Northampton and is supported by a nationwide network of approved dealers. It offers the lowest total ownership cost (TCO) of any lift truck brand (www.doosanforklifts.co.uk).

Doosan Industrial Vehicle is part of the $21-billion global Doosan Group (www.doosan.com), a South Korean conglomerate established in 1896, over 120 years ago, with products and services ranging from consumer goods to power plants, engines and construction equipment, including the global-leading brand Bobcat.

Allows users to store up to 75% more pallets than with selective racking

Steel King Industries, Inc., a leading manufacturer of material handling products and systems for improving operational efficiency, announces the availability of its Drive-In Rack Systems. Drive-In and Drive-Through Racking delivers cost-effective storage in high-density storage applications.

Requiring fewer aisles and providing better cube utilization than selective racks, drive-in and drive-thru racking allows users to store up to 75% more pallets than with selective racking. Forklifts drive directly into the rack, allowing storage of two or more pallets deep. Flared drive-in support rails helps forklift drivers enter the pallet rack by guiding the pallet into the bay. A Drive-In pallet rack system uses the same entry and exit point for each storage bay, providing last in, first out (LIFO) access. A Drive-Thru pallet rack system is loaded on one side and unloaded from the other for first in, first out flow (FIFO).

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Because they are often used in high turnover areas and operated in close proximity to forklift traffic, drive-in and drive-thru racks are subject to greater wear and tear than other rack structures. Steel King’s drive-in rack system is engineered and manufactured to better stand up to this wear, making it the market leader among drive-in racking systems.

Steel King’s drive-in racking features unlimited storage depth and is ideal for high-traffic and cooler/freezer installations. Additionally, Steel King offers an optional offset leg design for easier handling of pallets. The welded frame construction delivers high rigidity and strength, while other optional features, like protective railings and seismic-safe designs, deliver even greater safety and stability in demanding applications.

For more information about Steel King and Drive-In Rack Systems, visit https://www.steelking.com/products/drive-in-drive-through-rack/

About Us

Steel King Industries, Inc., is a leading manufacturer and integrator of material handling products and systems for improving operational efficiency in manufacturing, assembly, distribution centers, storage facilities, and warehousing.

Steel King is the nation’s only single-source manufacturer of pallet racks, drive in rack, flow rack, pushback rack, pick modules, mezzanines, cantilever racks, portable racks, industrial containers, custom shipping racks, and industrial safety guard railing.

Uniquely qualified to assist customers in planning and executing material handling systems, Steel King delivers reduced operation costs and increased customer satisfaction across a range of applications.

For additional information visit www.steelking.com

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