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Following the trend in automotive manufacturing, electric cordless tooling platforms are gradually being adopted for aerospace assembly tool systems. This paper introduces a new portable aerospace fastener assembly tool system based on the cordless electric technology platform. These systems are significantly more accurate than traditional pneumatic–based assembly tool systems and offer a range of process monitoring options. Cordless assembly tool systems make the assembly process easier, faster, safer and more accurate. These systems have the ability to provide traceability with time & date stamp for each installed fastener and provide wireless communication to enable process monitoring in real time. A comparison with traditional aerospace tool systems is made, in terms of historical evolution and working performance. Lessons learned from automotive applications are brought to aerospace industry. Key benefits include better ergonomics, improved accessibility, productivity and cost.

The installation of aerospace fasteners with pneumatic or cordless tools generally requires specialized systems which are dedicated to the fastener hex size and torque, often requiring laborious disassembly for a configuration change. This paper presents a quick change system that can be used together with a large variety of tooling configurations and provides instant socket exchange without requiring wrenching or disassembly. A comparison with traditional socket system is made, highlighting the characteristics and benefits of this new technology in terms of ergonomics, productivity and cost.

In aerospace fastener industry, all materials used or being considered for fastener applications must meet specified minimum shear strength values tested via single-shear test and double-shear test. However, shear testing results are not as precise as tension and compression testing due to the introduction of friction and bending forces in the testing process, resulting in the difficulty in obtaining accurate test data. Previous study showed the various effects of coating tribology on fastener single and double shear strength. Experimental results, statistical analysis and finite element analysis all confirmed that surface tribology could significantly affect the shear strength test results. Comparing to un-coated or bare fasteners, confirmed that fasteners from the same lot exhibited significantly lower shear strength values after coating. This effect is well known in the Aerospace fastener industry.

Cadmium (Cd) plating offers good corrosion resistance, lubricity, solderability, adhesion, and ductility, as well as consistent torque-tension and uniform thickness on components with complex geometries. However, the intrinsic Environmental, Health, and Safety issues associated with Cd have driven many users to seek alternatives. Currently, various Cd replacement teams/programs such as the Joint Group on Pollution Prevention (JG-PP)/Boeing, the Joint Cadmium Alternatives Team (JCAT), the Canadian Cadmium Replacement Program (CCRP), and the REFOCUS Program (AEA Technology, European) have been investigating alternatives to Cd plating. Some of the current coatings being considered in the aerospace industry include Zn-Ni alloy plating, electrodeposited aluminum, electroless nickel, nickel composite, and molten salt aluminum manganese (Al-Mn). Each option has its own particular characteristics; however, most experiments have been conducted on aerospace structural panels or components.

Cadmium electroplating is coming under increasing pressure due to both environmental and worker safety issues. Since 2005, Alcoa Fastening Systems (AFS) and Lockheed Martin have been conducting a collaborative research program to identify the most appropriate fastener coating materials for a Cadmium (Cd) plating replacement. Four candidate coatings were selected for the initial Phase I evaluation: electroless nickel (EN), electroless nickel composite (EN-PTFE), electrodeposited surface mineralization based zinc-nickel (Zn-Ni), and electroplated aluminum (Al). The Phase I testing results indicated that the Zn-Ni and Al coatings were the best of the four candidates for Cd replacement. However, it is hard to conduct direct comparisons with different coating thicknesses, surface treatments, and lubrication among various Cd alternatives. Thus, further evaluation with more careful control of these parameters would be necessary.

Since 2005, Alcoa Fastening Systems (AFS) and Lockheed Martin have been partnering to identify a Cadmium (Cd) plating replacement for threaded fasteners. Previously reported Phase I, II and III studies resulted in alternative coatings that indicated promise as suitable plating materials. Phase IV and V studies continued the program by testing two different fasteners (NAS1580 and NAS4452) manufactured in AFS facilities. Testing included plating material characterization such as coating thickness, torque-tension relationships, locking and breakaway torque measurements, salt spray (fog) corrosion, stress corrosion, and push-in and interference properties. Additionally, mechanical properties of the plated fasteners were tested (tensile, double shear, durability, and fatigue). Candidates included two electroplated zinc-nickel coating systems (Zn-Ni and Zn-Ni2) and an electrodeposited aluminum coating (AI).

Structural panel fasteners have been used in the aerospace industry for longer than the previous half century. This paper presents the new FC43® Panel Fastener with a novel retaining feature which enables the use of a full shank stud. The retaining feature can be used with a variety of thread configurations and is independent of nut style or head configuration, providing an unprecedented modularity for this type of fastening system. With a stud design that is free of slots or axial recesses, the FC43® provides higher mechanical performance than existing equivalent panel fasteners. Mechanical characteristics and performance comparisons with the most commonly used panel fasteners in the aerospace industry are also presented.

The Portable Fastener Delivery System or PFDS, has been developed at the Boeing St. Louis facility to streamline the manual fastener installation process. The PFDS delivers various fasteners, on demand, through a delivery tube to an installation tool used by the operator to install the fasteners in an aircraft assembly. This paper describes the PFDS in its current configuration, along with the associated Huck® International (now Alcoa Fastening Systems) installation tooling, as it is being implemented on the F/A-18E/F Nosebarrel Skinning application. As a “portable” system, the PFDS cart can be rolled to any location on the shop floor it might be needed. The system uses a removable storage cassette to cache many sizes and types of fasteners in the moderate quantities that might be required for a particular assembly task. The operator begins the installation sequence by calling for the particular fastener grip length needed using a wireless control pendant.

Multi-fastener lap joints are vulnerable to fretting fatigue when they are subjected to repeated loading. In general the fretting fatigue condition leads to degraded properties of metallic structures due to the presence of the surface stress concentration resulting at the sites of fretting pits. In many cases, fretting can result in premature structure failures therefore a series of counter measures are frequently taken to minimize fretting especially at the fastener holes. One of major factors that affect the fretting phenomena between the fastener and fastener hole is the surface condition of the fasteners. In this study, the influences of the surface texture and the surface plating of the fastener on the joint life were investigated by conducting double lap shear fatigue testing. It has been found that the joint fretting fatigue resistance is very sensitive to the surface texture of the fastener and as the surface roughness of the fastener is reduced the joint life increases.