Deutsche Edelstahlwerke possesses valuable in-house knowledge in the manufacture and further production of high-tensile steel. Based on their own test trials and in co-operation with RSA Entgrat- u. Trenn-Systeme, the quality and output of cutting-to-length has been optimized. The stainless steel manufacturer invested in an RSA saw line, type RASACUT SC with integrated deburring and fixed lengths control. The saw line is designed for the fully automatic process ranging from 200 up to 3,050 mm length and from 6 up to 30 mm diameter. Cuts that are not deburred can be processed even from a length of 30 mm upwards. Deutsche Edelstahlwerke guarantees tolerances of 1/10 of the DIN/ISO 10278 for exact lengths.

There is an increasing demand for high-tensile steel with specific properties. The comparatively new branch of wind power plants requires non-rusting, acid-proof and heat-resistant steel with specific properties. The aerospace industry now demands tenacity and hardness of the materials for aircraft including the Airbus A380. Power plant manufacturers are looking for innovative steel to increase their efficiency and the automotive manufacturers continue to progress towards a reduction in weight and number of pieces. Historically there have been production complications as tenacious and high-yield strength materials cause clogging during the cutting operation, for example, the cutters have difficulty gripping the material to form a defined and efficient cut which reduces the yield and lengthens the deburring process.

The quickest possible cutting time, optimum cut quality, and economical working life of the saw blade can be determined by considering the number of teeth. ‘When sawing, the exact setting of forward feed and cutting speed is dependent on the number of teeth of the saw blade with regard to quality and efficiency of the cut removal,’ says Markus Liedlich, Manager of bright steel manufacture for Deutsche Edelstahlwerke GmbH. The forward feed of the saw blade of the RASACUT SC is effected by means of a servomotor thus allowing to set the forward feed speed in dependency of the cutting volume fully automatically, depending on which point of the workpiece diameter the saw blade is positioned. A continuously adjustable and wide variety of speeds of the saw motor is the second condition for the efficient cut of high-tensile material.

This sounds complex in theory, but can easily be realized at the saw. The control system does not require any CNC knowledge of the operator for the setting of the parameters. Forward feed speed, cutting speed, and the number of teeth of the saw blade can be memorised as master data. The operator generally enters this master data and all further settings are automatically generated by the RASACUT SC.

A one-way carbide saw blade with a number of teeth between 80 and 120 has proven to be the optimum tool for the requirements of the bright steel factory of a stainless steel specialist in Hagen. ‘Certainly, economical results can be achieved with HSS blades too, if they are exactly suited to the workpiece. As we are frequently processing small batches of different materials, we have searched for an all-round blade aiming for a saw blade change only in case of wear’ Liedlich explains. Whether carbide or HSS blades should be preferred for materials which are difficult to cut, can not generally be answered. It is advisable to draw up an economic calculation for each production. A saw blade change at the RASACUT takes negligible time and improves the flexibility when choosing the right tool. Test carried out by the RSA engineers have shown significant advantages of carbide tipped saw blades over HSS blades for materials with a tensile strength > 900 N/mm².

Liedlich and his experts have also examined the solidity of the RASACUT saw line with particular emphasis on the saw gear. High strengths must be resisted when cutting high-tensile solid bars. Any play in the gear quickly leads to wear and a poor cut quality particularly in case of carbide saw blades. ‘We multi-oversized the gear unit in order to absorb even load peaks without any problems. By numerous production trials we have reached our goal to manufacture a gear nearly free from play, which works precisely in the long term, as well as when high-tensile steel is cut and even in three-shift operation,’ explains Rainer Schmidt, business manager from RSA.

Deburring

A high performance brush with wire trimming continues the quality and reproducibility of the deburring results. This method is about a cutting process because each wire tip forms a cutter removing the burr in the form of microscopically small cuttings. A special wire, developed by RSA, is suitable for high-tensile steel and grades with high yield strengths. It has a tensile strength of round 3,000 N/mm². With its natural hard structure, the wire achieves a higher impact strength than conventional final oil quenched wire. The wire has a long working life and provides a clean rounding of edges without a secondary burr. Short deburring times are achieved due to the tight wire trimming of the high performance roller brushes. A roller brush with a diameter of 300 mm and a length of 460 mm, which is used in automatic deburring machines, possesses round 390,000 wires, or cutters. In view of the high peripheral speed of 45m/s, an hourly output of 5,000+ pieces is achieved. Varying the wire thickness facilitates a precise adaptation to the material to be deburred. Appropriate high performance brushes with stainless steel trimming are available for workpieces made from stainless steel.

Prepared for the high requirements of the automotive industry

Deutsche Edelstahlwerke has always been an important partner for the automotive industry for the supply of special-quality steel. The company also sees itself as well positioned in the field for further industries. For example, spring steel with tensile strengths up to 800 N/mm² and dimensions between 9 and 14 mm diameter and lengths up to 3,000 mm are cut on the new saw line RASACUT. Rolling, hardening, and surface treatment processes and performed by the first and second tier suppliers. During the milling process, the homogeneity of the metal structure monitored along with the accuracy of the cutting to the fixed length. After sawing and deburring, the length of each piece is automatically checked. Workpieces outside of the determined tolerances are separated by a measuring module, which is integrated into the saw line. As a result, no faulty parts are delivered to the customer. Due to the modular configuration of the RSA saw line, the company is prepared for an extension by adding the processes of chamfering and cleaning as soon as such demands are made by the automotive industry.

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