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    Tooling

    Tools that give an extra lift

    • By Horn Cutting Tools UK
    • July 16, 2020
    • 6 minute read

    Based in Hohenlinden near Munich, Herrmann CNC-Drehtechnik GmbH has made a name for itself as a preferred supplier in the aerospace industry. Numerous aerospace OEMs rely on the precision and quality of the Bavarian machining specialist. To ensure the required quality, the machining experts at Herrmann use precision tools from Paul Horn GmbH.

    “When it comes to machining high-tech materials, we need suitable tooling solutions that can withstand high loads and live up to our quality standards,” says Production Manager Stefan Schubel. He uses grooving tools from Horn to make pedestal bearings from tempered steel.

    There is a common misconception when describing the extendable parts on a wing as ‘landing flaps are there for landing’. The correct name is a ‘high-lift device’ and these devices are required during take-off and landing to increase lift. Otherwise, the wing area would not be able to provide enough lift at low take-off and landing speeds. They also increase the drag when landing, as otherwise the speed would be too high and the wheel brakes could be overloaded. The pilot can extend and retract the slats (on the leading edge of the wing) and the flaps (on the trailing edge of the wing) to precisely control the lift. The slats and flaps are moved by means of a mechanism inside the wing and this is where the pedestal bearing from Hohenlinden comes in. The bearing transfers the torque of the linkage and compensates for axial play employing a spline. The pedestal bearing also serves as a flexible coupling between the shafts.

    Working with exotic materials on a day-to-day basis

    “Horn is constantly developing useful improvements to its tool coatings and cutting geometries. As a supplier to the aerospace industry, we spend every day working with special materials that are not always easy to machine,” explains Schubel. When it comes to grooving the hub and shaft of the pedestal bearing, Schubel and his team use tools from Horn.

    The bearing hub is made from 1.4548 (X5CrNiCuNb17-4-4), tough, high-strength steel often used in aerospace applications due to its high corrosion resistance and excellent mechanical properties. The machining experts at Herrmann CNC-Drehtechnik use the trochoidal grooving method to produce the large, deep recess in the workpiece. A full radius grooving insert from Horn’s S229 System with a radius of 2mm is used for roughing. For the substrate, Horn application engineer Korbinian Niedermeier recommended the AS66 grade. “In conjunction with Horn’s coating, this substrate is ideal for machining materials of this kind,” says Niedermeier.

    Trochoidal turning

    Trochoidal turning is ideal for turning deep, wide recesses where a high chip volume needs to be generated. “We have been actively using this method for around two years. We use the ESPRIT CAM system, as this software was one of the first to offer the option of trochoidal grooving,” says Schubel.

    The grooving process starts with a 30mm wide and 15mm deep (incremental) recess processed via trochoidal roughing with the full radius of the indexable insert with a cutting speed of Vc=140m/min and a cutting depth of Ap=1mm. The feed rate is set at Fn = 0.25 mm/rev and the finishing allowance is 0.2mm. Finishing is carried out on two sides with a 3mm wide insert with a corner radius of 0.2 mm that is selected from the S229 system. The total production time for the recess is under two minutes. “Thanks to this grooving method, we have no problems with long chips when working with a material that is difficult to machine,” says Schubel.

    The shaft of the pedestal bearing is made from SAE 51431 (1.4044), tempered to 1,350–1,500N/mm2. “It is often difficult to get hold of this special-grade steel. We purchase the material directly from the manufacturer in France, so we don’t order lots of different diameter variants. The smaller quantities of the components we are producing justify the high metal removal seen in some cases. However, we wouldn’t turn a 26.4mm shaft from a 55mm diameter bar,” explains the production manager. An insert from Horn’s 223 System is used for producing the 5mm wide recesses. In this case, each cutting edge has a life of over 300 workpieces. A Supermini 105 insert is used for internal profiling of the hole and the 45-degree chamfer. Finishing of the axial recess is also carried out using a Supermini. “These tools allow us to achieve the required surface qualities without any problems,” says Schubel.

    Focus on quality

    During production, the focus is always on the quality of the components. To meet the strict requirements for aerospace certification according to DIN EN: 9100, it is essential to have a clean and tidy working environment, highly qualified personnel and a quality assurance process featuring high-tech measuring machines. However, official certification inspections are not the end of the story because Herrmann’s customers also visit the site to carry out regular audits. “Cleanliness, precision and constant quality control are an absolute must when it comes to our everyday work”, says Schubel.

    The company produces every class of component for the aerospace industry, from Class 3 to Class 1. The most critical of these is the Class 1 component, the failure of which seriously jeopardises the safety of the aircraft. When a Class 2 component fails, it seriously impairs the ability of the aircraft to function but landing is still possible. The failure of a Class 3 component has no impact on functionality.

    Originally founded in a large garage back in 1986, Herrmann CNC-Drehtechnik GmbH now has 7,000 square metres of combined production and office space in Hohenlinden, near Munich. This Bavarian company, which employs 100 people, specialises in the manufacture of aerospace components. Thanks to its expertise in the machining of critical components and hard-to-cut materials, the company has established a very good reputation with numerous large aerospace corporations, gaining ‘preferred supplier’ status.

    The partnership between Herrmann and Horn spans more than 25 years. “Working with the technical advisers and Horn’s internal sales team is always a pleasant and productive experience. We look forward to continuing to use Horn tools and hope that Horn will continue to provide the same level of reliability and delivery performance in the future,” says Schubel.

    https://cdn.mtdcnc.global/cnc/wp-content/uploads/2020/07/16173410/24-25-Profiling-the-hole-with-the-Horn-Type-105-Supermini-system-scaled.jpg

    Tools that give an extra lift

    Based in Hohenlinden near Munich, Herrmann CNC-Drehtechnik GmbH has made a name for itself as a preferred supplier in the aerospace industry. Numerous aerospace OEMs rely on the precision and quality of the Bavarian machining specialist. To ensure the required quality, the machining experts at Herrmann use precision tools from Paul Horn GmbH.

    “When it comes to machining high-tech materials, we need suitable tooling solutions that can withstand high loads and live up to our quality standards,” says Production Manager Stefan Schubel. He uses grooving tools from Horn to make pedestal bearings from tempered steel.

    There is a common misconception when describing the extendable parts on a wing as ‘landing flaps are there for landing’. The correct name is a ‘high-lift device’ and these devices are required during take-off and landing to increase lift. Otherwise, the wing area would not be able to provide enough lift at low take-off and landing speeds. They also increase the drag when landing, as otherwise the speed would be too high and the wheel brakes could be overloaded. The pilot can extend and retract the slats (on the leading edge of the wing) and the flaps (on the trailing edge of the wing) to precisely control the lift. The slats and flaps are moved by means of a mechanism inside the wing and this is where the pedestal bearing from Hohenlinden comes in. The bearing transfers the torque of the linkage and compensates for axial play employing a spline. The pedestal bearing also serves as a flexible coupling between the shafts.

    Working with exotic materials on a day-to-day basis

    “Horn is constantly developing useful improvements to its tool coatings and cutting geometries. As a supplier to the aerospace industry, we spend every day working with special materials that are not always easy to machine,” explains Schubel. When it comes to grooving the hub and shaft of the pedestal bearing, Schubel and his team use tools from Horn.

    The bearing hub is made from 1.4548 (X5CrNiCuNb17-4-4), tough, high-strength steel often used in aerospace applications due to its high corrosion resistance and excellent mechanical properties. The machining experts at Herrmann CNC-Drehtechnik use the trochoidal grooving method to produce the large, deep recess in the workpiece. A full radius grooving insert from Horn’s S229 System with a radius of 2mm is used for roughing. For the substrate, Horn application engineer Korbinian Niedermeier recommended the AS66 grade. “In conjunction with Horn’s coating, this substrate is ideal for machining materials of this kind,” says Niedermeier.

    Trochoidal turning

    Trochoidal turning is ideal for turning deep, wide recesses where a high chip volume needs to be generated. “We have been actively using this method for around two years. We use the ESPRIT CAM system, as this software was one of the first to offer the option of trochoidal grooving,” says Schubel.

    The grooving process starts with a 30mm wide and 15mm deep (incremental) recess processed via trochoidal roughing with the full radius of the indexable insert with a cutting speed of Vc=140m/min and a cutting depth of Ap=1mm. The feed rate is set at Fn = 0.25 mm/rev and the finishing allowance is 0.2mm. Finishing is carried out on two sides with a 3mm wide insert with a corner radius of 0.2 mm that is selected from the S229 system. The total production time for the recess is under two minutes. “Thanks to this grooving method, we have no problems with long chips when working with a material that is difficult to machine,” says Schubel.

    The shaft of the pedestal bearing is made from SAE 51431 (1.4044), tempered to 1,350–1,500N/mm2. “It is often difficult to get hold of this special-grade steel. We purchase the material directly from the manufacturer in France, so we don’t order lots of different diameter variants. The smaller quantities of the components we are producing justify the high metal removal seen in some cases. However, we wouldn’t turn a 26.4mm shaft from a 55mm diameter bar,” explains the production manager. An insert from Horn’s 223 System is used for producing the 5mm wide recesses. In this case, each cutting edge has a life of over 300 workpieces. A Supermini 105 insert is used for internal profiling of the hole and the 45-degree chamfer. Finishing of the axial recess is also carried out using a Supermini. “These tools allow us to achieve the required surface qualities without any problems,” says Schubel.

    Focus on quality

    During production, the focus is always on the quality of the components. To meet the strict requirements for aerospace certification according to DIN EN: 9100, it is essential to have a clean and tidy working environment, highly qualified personnel and a quality assurance process featuring high-tech measuring machines. However, official certification inspections are not the end of the story because Herrmann’s customers also visit the site to carry out regular audits. “Cleanliness, precision and constant quality control are an absolute must when it comes to our everyday work”, says Schubel.

    The company produces every class of component for the aerospace industry, from Class 3 to Class 1. The most critical of these is the Class 1 component, the failure of which seriously jeopardises the safety of the aircraft. When a Class 2 component fails, it seriously impairs the ability of the aircraft to function but landing is still possible. The failure of a Class 3 component has no impact on functionality.

    Originally founded in a large garage back in 1986, Herrmann CNC-Drehtechnik GmbH now has 7,000 square metres of combined production and office space in Hohenlinden, near Munich. This Bavarian company, which employs 100 people, specialises in the manufacture of aerospace components. Thanks to its expertise in the machining of critical components and hard-to-cut materials, the company has established a very good reputation with numerous large aerospace corporations, gaining ‘preferred supplier’ status.

    The partnership between Herrmann and Horn spans more than 25 years. “Working with the technical advisers and Horn’s internal sales team is always a pleasant and productive experience. We look forward to continuing to use Horn tools and hope that Horn will continue to provide the same level of reliability and delivery performance in the future,” says Schubel.