The Mankiewicz Group supplies high-quality coating systems for industrial series production to various sectors. Ed Hill hears about its coatings used for aerospace applications.
In aviation Mankiewicz says it is the only supplier offering qualified materials in all three applications of an aircraft, namely interior, exterior and structural parts. Its products have to feature a complex set of resistances and strong properties with regard to durability and cleanliness in these environments.
When it comes to exterior coatings Mankiewicz first developed its BaseCoat/ClearCoat system in 2006, which was later adapted by other paint manufacturers. This two-layer, water based coating is said to take gloss retention and colour stability to technological extremes while at the same time allowing for quicker and more efficient application processes.
Andreas Ossenkopf, director and head of aviation at Mankiewicz Germany, explains: “The colour-giving BaseCoat layers achieve full coverage at very low film thickness. The majority of colours can be applied in just one coat and can be masked for the next colour in only two to three hours.
“Finally, all colours are sealed with one layer of UV protecting high gloss ClearCoat. The ClearCoat ensures optimum protection of the whole paint system including decorative and technical markings as well as rivets and avoids erosion. Also, chemicals like fuel and detergents have no chance to attack the painted surface. This leads to greater durability meaning the aircraft needs to be repainted less often.”
In interiors, there are various ways paint can be used with regard to design. Firstly, paint can be used as a substitute for materials that cannot be used in aircraft because they are too heavy, expensive or environmentally critical, for example, gold and silver.
“In this case, paints by Mankiewicz imitate their look and feel, being a perfect match to the aviation industries requirements,” Ossenkopf says.
Paints can also help create authentic looking surfaces with specific paint surface impressions. For example, surfaces can appear textured or smooth. With so called ‘flip effect’, paints can have transitions from one colour or shade to another. For hygiene-sensitive areas like lavatories or galleys, even further functions can be added. Antimicrobial coatings reduce bacteria growth without any toxic side effects and therefore reduce disinfection costs and prolong cleaning cycles.
There’s no question that paints used on aircraft face some of the harshest environments for a surface coating. Massive temperature fluctuations, corrosion, structural stresses, vibration, fatigue and exposure to jet fuels and other chemicals can all have an adverse impact on their performance.
Ossenkopf continues: “The harsh conditions that exteriors are subjected to between take-off and landing demand a lot of flexibility from the coating. Engine nacelles present particular challenges. The massive vibrations would cause any normal paint to crack so Mankiewicz has developed ALEXIT FlexPrimer, a product that is so flexible no cracks are able to form.
“For structural parts, the greatest challenge is corrosion protection that will last the lifetime of an aircraft. We have overcome this problem with the SEEVENAX structural primers we developed.
“In the interiors of cabins, the stress factors are of a completely different nature. The ALEXIT FST paints applied to these surfaces must withstand substances, such as cola, mustard and lipstick as well as being durable so that they resist damage from knocks or hastily stowed luggage.”
Put to the test
Mankiewicz paints have to fulfil the stringent safety requirements of aviation authorities, in particular fire safety and heat release. Mankiewicz has been DIN EN ISO 9100 approved since the 1980s. In addition to their high mechanical strength, chemical resistance and the long-term, high-quality finishes, the coatings can also add further features such as tactile appeal or extravagant designs that help underpin the comfort of passengers and boost the brand of an airline.
So, what are the biggest demands from OEMs and airline operators when it comes to paints?
“Shorter painting times and application reliability are the primarily called for by OEMs and tier suppliers as well as MROs,” Ossenkopf comments. “Deliveries of parts and aircraft are narrowly timed and painting is an important stage that must support Lean production processes.
“The automation of painting for interiors and structural parts is far advanced so Mankiewicz paints can be applied in serial production techniques, e.g. by robots and automatic spray-coating machines. Automation also plays a role when it comes to exteriors and we are actively involved with several partners in advancing this technology.
“Weight and aerodynamics are also a consideration. The minimal staining quality of ALEXIT BaseCoat/ClearCoat system, for example, helps in this respect. Any dirt that clings to the outer skin of an aircraft reduces its aerodynamics. Stains cannot adhere to the especially shiny and smooth ClearCoat. When countering weight, the high opacity of our paints even when applied in very thin thicknesses helps ensure that only minimal dry film thicknesses need be applied with this coating system.”
As well as aviation authority tests, paints are also individually developed to suit particular OEM specifications. The increased use of composite materials such as CFRP for aero structures has had a big impact on the coatings that Mankiewicz has introduced.
“We have developed and qualified a completely new product range of primers and fillers in close collaboration with OEMs for composites. These products solve the technical issues concerning pore coverage and long-term stability. Metal parts require corrosion protection, but composites do not. However, due to the processes of their fabrication the surfaces of composites are much more uneven than their metal predecessors.
“Despite the application of several coats of paint, such irregularities can remain clearly visible. As a consequence, we provide fillers for the various types of surface imperfections and production processes to make surfaces fit for finish. These include ALEXIT RapidFill, SEEVENAX KnifingStopper and for large irregularities SEEVENAX SprayFill for fast filling spray application.”
Airlines place great importance on their brands to enhance the passenger experience. Mankiewicz works closely with designers to achieve what is required.
Ossenkopf says: “This often involves the design departments of airlines and OEMs or independent design studios. The initial ideas for this are frequently developed using colour cards and effect patterns. Even at the early stages Mankiewicz works closely together with everybody involved and offers advice. To implement the ideas of the designers, we prepare colour samples of the desired effects and make these available to the designers and customers. The choices they select Mankiewicz subsequently puts into serial production.”
So, what are the next developments and trends anticipated when it comes to paint applied to aircraft?
“The automation of mixing and application processes is an important development to cope with the current ramp-up of aircraft production. A near-term objective is to develop chromate-free paint for structural parts that fulfil the same property profile, such as corrosion protection, as paint that currently contains chromates.
“Also, exterior surfaces of aircraft are now more frequently used as an advertising medium. Especially with Asian low-cost airlines who use the large surface area to sell this space to companies. Using BaseCoat/ClearCoat, creating these flying adverts is fast and easy and the colour depth and gloss are perfect for this purpose.
“In interiors customisation is increasing, along with customer demands for high quality. A high degree of homogeneity is also expected – the cabin should look as if it is painted all at once, even when assembled from the parts made in different locations and under varying conditions around the world. The Mankiewicz FST interior paint fulfils those demands.”