Production presses ahead

The loads and forces encountered by parts in helicopter transmissions are some of the most demanding in aerospace. Any failure can lead to disastrous consequences so components have to be made to exacting standards in order to pass the stringent quality certifications and specifications required. However, as in all manufacturing, cost and efficiency of the production process needs to be considered, especially in the competitive supply chain that the aerospace sector epitomises.

Dietzenbach, Frankfurt-based precision engineering specialist, Georg Martin secured a contract in May 2013 to supply a ready-to-install formed steel part for helicopter transmissions for a major helicopter manufacturer.

The ring shaped component, manufactured from Stainless Steel 1.4554 with a weight of 102grams, was made using Martin's advanced forming technology and expertise.

The three-dimensional precision formed part has numerous drill holes. It has an outer diameter of 200mm and wall thicknesses of up to 1mm and satisfies the high precision and quality requirements for transmission elements in the aviation industry.

Management board member, Christoph Martin explains how the company applied its forming expertise acquired in the automotive sector to manufacture the part.

“Forming is a process that has been typically used in the automotive industry for the production of parts in the drive train. In terms of cost and weight it was a very clever solution for this aerospace application despite the fact that the production volume is only about 12-24 pieces per year. At Georg Martin we also managed all the necessary production steps internally which contributed to a good price-value relation for its production.”

<Adding integration>

A requirement for the successful production of the transmission part was an intelligent combination of numerous production methods and in-house processes. It involved Martin's own toolmaking, as well as the use of state-of-the-art measuring and testing technology. In addition to deep-drawing, bending and punching, the company's range of metalworking capabilities includes all aspects of machining technology, including laser cutting and combined CNC laser cutting and punching; all of which were used in the production of the component.

“The toolmaking was done via Catia V5's design software and CADCAM processes,” Martin reveals. “Due to the low production volume we used, amongst other processes, hydraulic double action presses for the deep-drawing element and tried to integrate as many of the other production steps in the press process as we could. Nonetheless, some of the borings needed to be done before and after the forming process so in those instances we used chip removal and a special fine laser cutting process to complete the part.”

Quality of the part was guaranteed using optical and tactile systems on 2D and 3D measuring machines of the latest generation. This enabled the company's forming technology arm to provide a solution that was tailor-made for the manufacture of the geometrically complex formed part.

“We use Schneider optical and semi-optical systems of the latest generation to counter check the production step stages and ultimately the final result. Likewise we can also provide Statistical Process Control (SPC) data if the customer requires it.”

Georg Martin's other manufacturing capabilities include the production of complete sub-assemblies with numerous connection and joining technology processes, from riveting and flanging through to (non-aerospace certified) WIG and MIG/MAG welding and also gluing. High-quality surface and heat treatment is subcontracted through close cooperation with its partner companies.

<The spacers in between>

Although the production of the helicopter component is a relatively new development for Georg Martin, it also supplies shim solutions to the aerospace sector. The company's shim products are made both from metallic and plastic/composite materials. It is one of the top companies in Europe manufacturing high-quality shims for quick and low-cost tolerance compensation of components when mounting sub-assemblies. Its laminated, packaged and solid shims of the M-Tech product family can be found in many sectors but especially in the drive technology, mechanical engineering and aviation industries.

“In 1956 we took over the manufacturing of laminated shims under license from an American company and have continued to develop these types of products ever since. We supply laminated and solid shims to the Airbus Group on a frame contract basis. Our history in the aviation industry goes back to the Franco-German Transall military transport plane and the A310.”

One of Martin's most widely used products is its peelable shims, widely found in the aviation industry. Its Laminum HP1 laminated peelable shims are made of foil sheets which can be reduced by layers of 50µm down to thicknesses of 25µm for gap management applications, notably transmission assemblies in aviation. Similarly its M-Tech L laminated shims, made from polyethylene terephthalate (PET), consisting of 100µm layers can be used for similar applications where thermal stability, lightweight, chemical resistance or electrical insulation properties are required.

“Today we deliver to Airbus Helicopters, Rolls-Royce, Goodrich, MBDA, Diehl, Ruag, Pilatus, DLR and others. The company's aerospace competence was confirmed in 2009 by EN 9100 certification and in 2012 we achieved an outstanding result with a rating of 95% in an Industrial Process Control Assessment (IPCA) audit conducted by Airbus.”
After the successful production of the helicopter part the company is keen to apply the lessons learned to further manufacturing possibilities.

Martin concludes: “We have successfully achieved series approval for this part and we are planning to extend further on our capabilities in low and middle quantity manufacturing of sheet metal complex parts. The project allowed us to integrate our manufacturing capabilities from the shim manufacturing and the forming parts side of the business, and also to be able to verify the production steps with our new 2D and 3D optical measurement systems.

“The maximum dimensions available are approximately 700 by 1,000mm die sizes for the forming and deep-drawing process and 1,000 by 2,000mm for the laser cutting and machining. Our aim is to produce more integrated parts for easier assembly in aerospace, as we do for the general and automotive industries.”

www.georg-martin.de