Лако-красочные материалы — производство

Bonding technology as a high-performance joining technique for extremely long-life and heavy-duty structures was developed in aircraft manufacture, where it proved to be a success despite some critical periods during development. This technology clearly contributed to improvements in aircraft structures, and will continue to be essential in aircraft manufacture, notably when fiber-reinforced plastics are taken into consideration. Although, it seems unlikely that the costs ofthis labor-intensive production process will be greatly reduced, the development of bonding technology may in fact now occur in reverse sequence. Whereas, technology as a whole has learned from aircraft manufacture, it may now be expected that aircraft manufacture may draw lessons and gain experience from other fields of technology (e. g. car manufacture), in order to simplify and cheapen its processes (see Section 8.2.2). It is important, however, to take into consideration that the performance of aircraft differs greatly from that of other technical products. For mere reasons of amortization, a modern civil aircraft must achieve a service life of 20-30 years, most of which time it spends in the open air and often under difficult climatic conditions. During the flights, there are high mechanical stresses present, yet any adverse outdoor condi­tions must be considered noncritical. Within the aircraft fuselage, due mainly to exhalation by the passengers, considerable moisture accumulates and begins to freeze on the outer wall, later accumulating in the lower fuselage area as condensed water. In fact, when a wide-body aircraft lands in a tropical zone, between 1 and 1.51 of condensed moisture is present on the lower fuselage area, containing highly corrosive components and requiring removal. While an aircraft is on the ground at airports, it is mostly unprotected with regards to corrosion and intense UV radiation. When compared to a car — which may have a maximum service life of 15 years, a total operating time of 4000 h, with a total distance covered of about 200 000 km — an aircraft would be expected to have a service life of 30 years, and to be actually flying for between 30 000 and 60 000 h. Within this operating time, the taxiing alone of an aircraft, especially when operated on short distances, would involve a distance of about 300 000 km far more than would be expected from a passenger car. Finally, it must be mentioned that, for a heavy airliner, a general check­up — with an inspection of all structural components — is scheduled after about 5000 operating hours. This means that absolute reliability of the joints must be ensured over a time period that largely exceeds the running time of a passenger car. Clearly, such reliability can only be achieved by means of a highly labor-intensive production.

Yet, in aircraft manufacture — when compared to automobile construction — a certain residual risk of the technology is possible without any loss of safety, because at all times every aircraft in operation is registered as to its whereabouts and operational period, worldwide, whereas cars will not be within easy reach of central organizations on a continuous basis. If it is necessary to perform certain constructive design optimizations on an aircraft — whether rework or repair — this may be done worldwide, utilizing a common practice. In this way it is clear that bonding technology has contributed considerably to reducing the predominant problem in aircraft manufac­ture, namely structural failure, which in earlier times would often require reworking to be carried out. Moreover, this approach has not only saved costs but also considerably improved passenger safety.

8.2.2