Today’s sealing solution providers need to continually adapt to ever-changing aero engine manufacturing demands if they are to maintain their fit within the aerospace supply chain. Mike Richardson reports.

In our desire to travel further, faster and higher than was previously possible, the industry must continually discover ways around severe environmental barriers, with extreme heat and cold, pressure and moisture just some of the hostile elements challenging today’s aircraft design. In addition, the aircraft systems themselves can include manmade compromises to design integrity with corrosive oils, fuels, de-icing fluids and other hydrocarbon and synthetic solvents that add to the test of every successful flight.

With so many critical aerospace applications dependent on the technology that seals them, and with the safety and sustainability of air travel absolutely paramount, it is clear that there can be no second-guessing the quality and integrity of sealing systems.

Simrit is the industrial sealing products division of Freudenberg-NOK Sealing Technologies and one of the world’s largest suppliers of elastomeric seals and custom moulded products.

Taking the heat

The company’s vice-president of global sales, aerospace, Vinay Nilkanth outlines the current challenges placed on Simrit by aero engine manufacturers in terms of designing today’s aero engine for tomorrow’s aircraft.

“Aero engine manufacturers are faced with the increasing demand of enabling airline passengers to travel around the world faster,” he states. “As a result, passenger aircraft are flying at higher altitudes to reduce resistance to drag which also means using less fuel. Fuel burns far more efficiently at higher operating temperatures, which means manufacturers are looking for increased temperature capabilities from the aero engine. However, with aircraft flying at higher altitudes, air temperatures can be as low as -55ºC, and there are even discussions in industry about whether an aero engine can withstand operations down to -80ºC. This presents a tough challenge for the elastomer seal industry in terms of finding real solutions to withstand these extreme temperatures.

“Another industry trend involves ever-tightening aerospace specifications. The aviation industry is incredibly safety conscious so quite rightly, increasingly stringent requirements are being put in place and the material and dimensional specifications tightened accordingly. We are seeing tighter requirements in terms of dimensional tolerance values on the sealing parts we produce. Meanwhile, Europe appears to be taking a much bigger lead on environmental legislations such as REACH, and whereas customers used to ask us whether we are compliant to REACH, they are now demanding that we are compliant.”

In terms of the latest technology evolutions within the design of elastomeric sealing materials for aero engine sealing solutions, Simrit provides fire resistant and fireproof products by using proprietary formulations, fabric reinforcement, and fire protection designs.

“The fireproofing and fire resistance capabilities of elastomers and sealing products are a key area for investigation by Simrit and involve continual improvements in the manufacture of seals with speciality fabrics to ensure our products are resistant to flame propagation,” continues Nilkanth. “High temperature flame resistance is very much desired from a fire barrier standpoint. High temperatures above 320ºC require metallic seals and we are seeing an increasing requirement for these products as temperatures escalate. In the high compression area of the engine we’re seeing increasingly more demanding applications for these types of seals.”

Material innovations

According to Nilkanth, Simrit has been working hard on material development because no matter how good a seal design is, if a material cannot sustain high temperatures around it then there will always be limitations to its suitability.

“Material development is by far the most important aspect for Simrit and it is where our main focus lies,” he notes. “It is vital that we promote the correct fabric reinforcements to ensure we cover the entire design aspect. We are also interested in expanding our product portfolio and continuing to provide further advancements in our seal offerings.”

Whilst Simrit’s product portfolio of aero engine-related products helps provide its customers with solutions over and above the more conventional seal designs, it’s interesting to know what else the company is doing to improve its customer offerings. Price, delivery, quality, service/support and global presence are all a given, so what else is it doing to differentiate itself from the competition?

“We have a very strong Lean manufacturing ethos running through the company,” states Nilkanth. “Our continuous improvement programme is called GROWTTH, which stands for ‘Get Rid Of Waste Through Team Harmony’. Our parent companies Freudenberg and NOK Sealing Technologies have taught us a great deal in terms of Lean manufacturing and Six Sigma principles, and although these philosophies are commonplace in the automotive arena, they are becoming increasingly demanded by the aerospace sector because of the desire to instil these kinds of quality improvements on the OEM’s aircraft production line. This plays to our advantage and we are working with major engine and airframe companies in cooperatively developing systems with Lean systems in mind.”

The challenges ahead

Nilkanth concludes by offering his view on the kinds of developments that the aerospace industry might well be seeing in the future to help further improve sealing solutions around the aero engine.

“One of the areas we are spending research and development time on concerns the increasing demand to examine the role of elastomers in conjunction with alternative fuels sources such as bio fuels for example. These challenges will mainly involve studying the compatibility aspects of our materials when used with bio fuels.

“Another area concerns the various Nacelle systems used with aero engines. Weight reduction continues to be a huge driver and is not only connected to airframes, but to areas around the engine as well. As a result, there is increasing customer demand for weight reductions on sealing components. We have developed some very interesting low density materials that will result in 15-20% weight savings compared with traditional elastomers and therefore offer additional fuel efficiency for nacelles and engines.”

www.simrit.com