Showcase In Aerospace

Six hundred tubes for one aircraft: Meeting the production demands at a Tier 1 aerospace supplier

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Tubes and Ducts Maroc (TDM) Aerospace was founded in Morocco in 2018. The company manufactures tubes for the aerospace industry and acts as a Tier 1 supplier for well-known aircraft manufacturers. TDM, which is based at Mohammed V Airport in Casablanca, currently employs 70 people and is a showpiece in the North African country’s strategy to become a major global location for aerospace system and module suppliers in the coming years.

To this end, the Moroccan Aerospace Investment Co. is investing in businesses like TDM and holds a majority stake. Morocco aims to further expand aerospace activities to create local supply chains and make the country a major trading partner. A number of free trade zones have been set up, and the kingdom provides targeted support for companies in the aviation industry, for example offering financial assistance for employee training and granting other privileges.

Tubes and Ducts Maroc (TDM) Aerospace manufactures tubing for the aerospace industry and acts as a Tier 1 supplier for well-known aircraft manufacturers.

To adhere to the strict production requirements of tubes for its aircraft manufacturing customers, TDM relies on Schwarze-Robitec, an experienced tube bending machine manufacturer for its equipment. Precisely and consistently producing tubes of various geometries, the modern production facility is seen as a showcase project for the country.

A competent partner

The founders of TDM have more than 60 years of experience in tube manufacturing for the aerospace industry. For the demanding production of tubes for hydraulic lines as well as cooling water, wastewater and brake lines in aircraft, they were looking to find a manufacturer of tube bending machines with many years of expertise in the aerospace industry.

“We needed a partner that could support us not only with high-quality technology, but also with expert advice,” says Jürgen Viehrig, CEO and co-founder of TDM. “Schwarze-Robitec has been active in this field for more than 50 years and knows the special requirements regarding surface finish, wall thickness and ovality down to the last detail.”

For the tube bending process, TDM uses two Aircraft Edition tube bending machines from Schwarze-Robitec: the single-stack CNC 40 E TB and the CNC 40 Rotary with rotating bending head.

After all, production of tubes for the aerospace industry requires the utmost precision. Tight tolerance specifications must be adhered to, and the tubes must be manufactured so that they are completely wrinkle-free in an approved process.

Lean manufacturing

At TDM’s new production plant, the tubes are first cut to size, then bent and measured. This is followed by the grinding, polishing and joining of tubes with fittings in an orbital welding process. With the aid of a digital X-ray machine, the tubes are inspected, then submitted to a pressure test before they are cleaned and dried. The next stages are then marking, quality assurance, packaging and shipping.

For the bending process, the company uses two Aircraft Edition tube bending machines from Schwarze-Robitec: the single-stack CNC 40 E TB and the CNC 40 Rotary with rotating bending head. The machines bend titanium and stainless steel tubes with diameters ranging from 6.35 mm to 31.75 mm.

“We have the capacity to produce 400,000 tubes a year,” Viehrig says. “Here, we focus not on the production of replacement or special parts, but rather on semi-automated and lean production in large series.”

The aircraft manufacturer produces several aircraft in a month with around 600 different tube systems required for a single aircraft. Each component is a unique piece.

For particularly complex geometries such as coiled tubing, the CNC 40 Rotary is used with an independent axis for the bend die.

To bundle its capacities, TDM manufactures in batches of one to 10, delivers the required quantity and stores the remaining components until the next time the customer requests the parts. For particularly complex geometries, the CNC 40 Rotary with an independent axis for the bend die is used. The option of flexibly moving the bending head to the left or right side is used for around 20 percent of the components.

Thanks to modern CNC technology, multi-dimensional tube systems can be produced precisely and reliably without welding in a single work step. This way, coiled tubing and pocket tubes are produced in the shape of an angular U, for example. Such tubes are used frequently in aircraft to compensate for expansion and vibration.

Demanding material

Requirements for production are exacting. Not only do tubes with relatively large diameters and very thin walls need to be bent, but also, the material used is titanium, which has a high strength. This means the bending process must be very slow and at the same time vibration-free. Despite the thin wall thicknesses of 0.56 mm to 0.88 mm, it is important that no cracks or folds occur during bending.

“From a purely technical point of view, this is a major challenge,” says Philipp Knobloch, global sales director for new machinery equipment at Schwarze-Robitec. “A high torque is required to achieve a smooth movement, but the slowness of the motion means there is a risk of vibrations occurring, which can lead to wrinkles.”

A special feature of the CNC 40 Rotary, which allows the bending head to be moved flexibly to the left or right side, is used for approximately 20 percent of the components.

Special devices such as wiper dies help to counter this. Titanium is lightweight, strong and corrosion-resistant, making it particularly important for aerospace engineering, yet the material is very brittle and can crack easily. Special attention must also be paid to the surface finish, hence the percentage of dents, scratches, wrinkles and notches must not exceed 1 percent in depth, measured against the tube diameter. On top of that, ovality must be less than 3 percent as the tubes must have almost perfect roundness to ensure ideal flow properties.

The smallest product defects can have fatal consequences. Leaks in hydraulic tubes, for example, can prevent the landing gear from extending and the aircraft from landing. If fuel leaks from a tube and drips onto a hot spot, the worst-case scenario is a fire in the aircraft.

Demanding results

Aircraft manufacturers place high demands on their Tier 1 suppliers in terms of quality and safety. Not only are the components subjected to exacting controls, for example, but the entire production process also has to be validated. The tube manufacturing process at TDM is, therefore, subject to strict regulations and compliance that is checked and audited on site on behalf of the aircraft manufacturer. In this context, there are also separate requirements for the manufacturer of tube bending machines.

“Thanks to its many years of experience in the aviation sector, Schwarze-Robitec knows the specifications exactly and can meet them without any problems,” Viehrig explains. “In addition, the contact persons have been and continue to be available to advise us at all times and have thus also provided valuable support for the entire certification process.”

In addition to the two tube bending machines, Schwarze-Robitec supplied a photometric measuring cell that can be used to determine tube geometries, lengths between bends, bending angles and other important parameters.

TDM has obtained numerous qualifications in recent years and also meets, for example, the quality management system standard DIN EN 9100, which applies specifically to aviation.

With the two tube bending machines in its Aircraft Edition, Schwarze-Robitec ensures extremely precise bending results. “The accuracy can be increased even further through targeted control of the axes and amounts to ± 0.05 mm,” Knobloch explains. “For the orientation angle and bending accuracy, the result is 0.05 degrees.”

The tube bending machines are designed for use under continuous and long-term stress. The robust design enables reliable operation without malfunctions or unnecessary process interruptions, something that is particularly advantageous in countries with weak infrastructure, where there is no close-knit network of specialist companies on standby in the event of disruptions.

“The results speak for themselves: Ovality is less than 3 percent and the surfaces are excellent – completely wrinkle- and scratch-free,” Viehrig emphasizes . “At the same time, we achieve very precise results with low tolerances even with our most complicated tube geometry with 16 bends.”

Going beyond

Before TDM contracted Schwarze-Robitec to supply the two tube bending machines in 2019, a preliminary acceptance test was carried out at the German machine manufacturer’s plant in Cologne. Based on the machining of 10 selected components, the bending machine manufacturer ensured that all specifications were met and already delivered flawless bending results there.

TDM then put the bending machines from Schwarze-Robitec into operation in Casablanca in early 2020. Included in the delivery was a photometric measuring cell that can be used to determine tube geometries, lengths between bends, bending angles and other important parameters. Following the commissioning, TDM employees received extensive on-site training with follow up training taking place several months later.

The tube bending machines are designed for use under permanent and long-term stress.

“One of the biggest challenges was that we had to implement production here on site without skilled workers,” Viehrig says. “This meant that training was crucially important for us. In Schwarze-Robitec, we found a reliable partner who actively supported us beyond delivery and commissioning.”

The supplier-customer relationship, he explains, is open, honest, trustful and transparent. At Schwarze-Robitec, customer proximity is an integral part of the package, even across distances. Hence, the experienced service team is on hand to identify and solve potential problems remotely or to carry out maintenance and repair work directly on site.

Over the next few years, the Tier 1 supplier intends to expand its capacities and is, therefore, planning to install up to three more tube bending machines. In doing so, TDM hopes to continue working with the experienced specialist from Cologne.

Schwarze-Robitec

Tubes and Ducts Maroc Aerospace

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