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Silicone rubber is comprised of inorganic-organic polymers. These materials consist of an inorganic backbone with organic side groups attached to silicon atoms. This family of polymers possesses unmatched versatility giving the formulator and user multiple forms and methods to cross link the polymers into rubber materials having the widest service temperature range of any rubber material. This course is designed to provide the participant with a thorough understanding of silicone’s engineering characteristics.

Radio Frequency Identification (RFID) is an enabling technology that has been widely adopted in the retail industry. The powers of RFID are acknowledged by many, but a lack of understanding of the technology, its limitations, and how to select the right plan for its target installation has slowed efforts to migrate the technology into the aerospace, space, and transportation industries. While RFID is not a new technology, the rate at which it has been integrated into the aerospace industry has been slow due to unique considerations regarding qualification, regulations, and safety.

The aerospace industry has long sought a solution for storing maintenance history information directly on aircraft parts. In 2005 leading airframe manufacturers determined that passive Radio Frequency Identification (RFID) technology presented a unique opportunity to address this industry need. Through the efforts of the Air Transport Association (ATA) RFID on Parts Committee and SAE International testing standards and data specifications are in place to support the broad adoption of passive RFID for storing parts history information directly on aircraft parts. The primary focus of the paper will be on the SAE AS-5678 environmental testing standard for passive RFID tags intended for aircraft use. Detail will be provided to help aerospace manufacturers understand their role and responsibilities for current programs and understand how this may impact their parts certification process.

Probabilistic methods are used in calculating composite part design factors for, and are intended to conservatively compensate for worst case impact to composite parts used on space and aerospace vehicles. The current method to investigate impact damage of composite parts is visual based upon observation of an indentation. A more reliable and accurate determinant of impact damage is to measure impact energy. RF impact sensors can be used to gather data to establish an impact damage benchmark for deterministic design criteria that will reduce material applied to composite parts to compensate for uncertainties resulting from observed impact damage. Once the benchmark has been established, RF impact sensors will be applied to composite parts throughout their life-cycle to alert and identify the location of impact damage that exceeds the maximum established benchmark for impact.

General Agreement to revise specifications testing requirements for AMS2301 and AMS2304

This hands-on manual provides a systematic method for identifying standard drills, standard taps, and various types of hand, machine and shell reamers used in industrial applications. Complete contents include: J2122 - Numbering System for Standard Drills; J2123 - Numbering System for Standard Taps; and J2124 - Numbering System for Reamers. A complete appendix section listing numerous examples of standard tool designations using the numbering scheme is also included. A valuable reference that will help OEMs and suppliers effectively communicate tool descriptions, as well as more efficiently catalog and supply tools!

AFTER outlining the progress of research in the development of the alloy steels, the author says that alloys of steel containing nickel, chromium, and nickel and chromium, are the most important to the automotive industry, which is especially interested in alloys containing up to 5.0 per cent of nickel and up to approximately 1.5 per cent of chromium, with the carbon content ranging from 0.10 to 0.50 per cent. The additions of these amounts do not materially change the nature of the metallographic constituents, but the elements exert their influence on the physical properties largely by altering the rate of the structural changes. In straight carbon-steel, especially of large sections, it is not possible by quenching to retard the austenite transformation sufficiently to produce as good physical properties as are desired.

PROVISION is made, in the piston and rings described by the author, for an adequate flow of heat from all parts of the piston-head to the cylinder-wall by means of adequate cross-section of aluminum alloy in the head and a tongue-and-groove type of piston-ring structure which provides a greater amount of surface than is usual for heat transfer. A labyrinth oil-seal is provided which aids heat transference and prevents leakage past the piston-rings, and the heat transfer is said to be such that the heat does not destroy the oil seal between the piston and the ring. Charts are included that show the effects in reduced temperatures, oil consumption and gas leakage with the construction described. Attention is given also to a skirt construction most suitable to use with the piston-head and rings described.

ALUMINUM and magnesium, being the lightest commercial metals and therefore the most suitable for aircraft construction, are discussed in their pure and alloyed states. Physical properties of the pure metals and their alloys are given and the effects of adding small quantities of alloying elements are shown. Heat-treating as a means of increasing the strength per unit weight of the alloys is discussed at length, together with the effects of natural aging and artificial aging at elevated temperatures and of quenching in hot and in cold water after heat-treating. The several types of corrosion are considered and resistance to corrosion of the metals and their various alloys are discussed. Protection afforded to aluminum alloy by a surface coating of pure aluminum is described, and other methods are mentioned.

A NUMBER of the more important commercial alloys having aluminum as their base are discussed by the author, who points out their main physical characteristics and outlines methods which can be used in their fabrication, indicating in a general way which alloys are best suited to various aircraft-engine requirements. Tables are given showing chemical compositions and physical properties, including a table of physical properties of various casting alloys at elevated temperatures. Special-purpose alloys are commented upon, and also a new aluminum alloy for pistons which is beginning to find commercial application and possesses properties particularly desirable in aircraft engines. Recent developments in magnesium alloys and their application to aircraft-engine design are specified, tables of physical properties are given, and comments are made on the characteristics of the material as compared with aluminum alloys.

AT first believed immune, aluminum alloys have been found extremely susceptible to both surface corrosion and intercrystalline corrosion. The latter goes on under paint that has been applied to imperfectly cleaned surfaces, and shows only as blisters. Because of this, it has become commonplace to break with the fingers the ribs and the trailing edges of duralumin lower wings and tail-surfaces. Contact of duralumin with brass or steel hastens corrosion, and protective paint coverings are dissolved by dope where fabric surfaces meet metal parts. All-duralumin structures are not considered suitable for sea-going aircraft unless all joints and seams are of water-tight construction, not only in hulls but in other members of the structure. Corrosion over the land is much less severe. Few manufacturers seem awake to the importance of corrosion. The fight to avoid it should begin with avoiding seams that are difficult to protect and hollow members that cannot be sealed hermetically.

SEVEN basic copper-tin-lead bearing-bronzes having high copper contents were studied by the application of various mechanical tests, such as Brinell hardness, resistance to impact, resistance to repeated pounding and resistance to wear. The effects of various additions were investigated by preparing test bearings of the same base alloys with additions of zinc, phosphorus, nickel and antimony, taken singly, and applying the same tests to these. The preparation of the test castings and the methods of testing are described in detail. The chemical analyses are given for the 40 different alloys tested; and the results of the various tests on each group of alloys are reported and discussed in detail, with the observations charted and tabulated for convenient reference. A tabulation of the specifications of 54 different bearing bronzes now in use is included in the paper. Dr. Dowdell presented and discussed∗ the paper for the authors.

EITHER steel or cast iron will provide a good braking surface provided the grain structure is laminated pearlite, according to the author. Such a structure can be secured in pressed steel by alloying or by case-hardening, in high-carbon steel rings welded to a stamped back and in centrifugally cast iron by careful control without alloying. Uniformity of analysis is important and control of the rate of cooling is still more important in castings. The graphite content of iron is not considered important as a lubricant. Methods of centrifugal casting and of testing are illustrated; also the form and microstructure of representative brake-drums. Discussers agree as to the microstructure needed and present additional views as to ways of securing that structure and the desirability of capacity for absorbing and dissipating heat. They believe grain size and strength more important than hardness.

TRAILER registration figures for the entire United States are given to show the rapid increase in the use of trailers in the last seven years, and, for comparison, State registrations of all motor-vehicles in 1931 are given. To account for the relatively more rapid increase in trailers than in trucks, factors favoring the use of trailers are mentioned and illustrative examples of operation are briefly described. The factor of first importance is legislation, which in general is stated to have promoted the use of trailers to distribute the weight of heavy loads over more axles and wheels; but in some States the laws and regulations have a serious adverse effect. Next to legislation, savings in hauling costs through the use of trailers account for the increase in their numbers, and comparative figures of the cost of hauling per 100 lb. per 100 miles by truck, by truck and trailer and by rail are given to show the economy.

METALLURGISTS must supply engineers with data on the physical properties of steels so that the skill of both can be used, particularly for machinery in which light weight is essential. The engineer who has not a metallurgical department at his command cannot be sure of duplicating results claimed by steel makers, and the physical-property data that have been given in the S.A.E. HANDBOOK are based on minimum results, for safety. More complete information as to what actually can be expected is desirable, and a subcommittee has had a large number of tests made on identical samples from several heats of two alloy steels. The results for these two steels have been coordinated in probability curves that were developed with the aid of frequency charts. Some steels are not uniform in their physical properties in large sections. The author presents suggestions for steels that are suitable for large sections, with the strengths that can be expected from them.

INCREASED quality, which is reflected through higher valve-seat hardness and improved microstructure, can be obtained by additions of nickel and chromium to automobile-cylinder iron. Different combinations of these alloys were used, and it was found that a ratio of three parts of nickel to one of chromium gives the greatest improvement in structure in conjunction with maximum hardness. The effect of prolonged heating on three representative plain irons, as well as on three nickel-chromium-alloyed irons of the same base composition, is also shown. A marked difference is revealed in these cases in favor of alloyed irons. A method is given of producing chilled roller wheels by additions of chromium in the ladle instead of using special cupola charges. This is capable of better control and results in a superior product.

ACHIEVEMENTS of the last ten years in increasing the power-weight ratio of aircraft engines are stated and contributing factors are analyzed. Aluminum alloys have replaced cast iron and steel for certain parts, not entirely because of their lower weight but because of a combination of properties which better fit them for the task. Similar considerations must govern the replacement of aluminum-base alloys by those of magnesium. The most promising immediate field for the magnesium alloys is said to lie in applications wherein strength and lightness are the main considerations and high-temperature properties are of secondary importance. Properties of magnesium castings and forgings are compared with those of castings and forgings of the aluminum alloys. Features of design are discussed which should receive special attention when changing a part from aluminum to magnesium. Machining practices for magnesium are covered in some detail.

COMPARATIVELY large rake and clear angles required for best results leave a relatively thin cutting-edge on a cutting tool for aluminum. One difficulty encountered is that tools of such form are not always available or suitable, for various reasons, for instance, small tools of various types are available only with cutting edges suitable for steel and bronze, and the desirable amount of top rake cannot well be provided on circular form-tools. Tool bits of various sorts can be reground to the desired angle. A simple round form of tip that is shown can be utilized in tools for various purposes, including use as inserted teeth in a face-milling cutter. High-speed-steel tools are suitable for most aluminum alloys, but alloys containing a high percentage of silicon can be machined to advantage only by using cemented tungsten-carbide. Machine-tools should be suitable for high speed.