Author Description

This manual was written for design engineers to enable them to choose appropriate fasteners for their designs. Subject matter includes fastener material selection, platings, lubricants, corrosion, locking methods, washers, inserts, thread types and classes, fatigue loading, and fastener torque. A section on design criteria covers the derivation of torque formulas, loads on a fastener group, combining simultaneous shear and tension loads, pullout load for tapped bales, grip length, head styles, and fastener strengths. The second half of this manual presents general guidelines and selection criteria for rivets and lockbolts. To the casual observer the selection of bolts, nuts, and rivets for a design should be a simple task. In reality it is a difficult task, requiring careful consideration of temperature, corrosion, vibration, fatigue, initial preload, and many other factors. The intent of this manual is to present enough data on bolt and rivet materials, finishes, torques, and thread lubricants to enable a designer to make a sensible selection for a particular design. Lockouts, washers, locking methods, inserts, rivets, and tapped holes arc also covered. Bolts can be made froni many materials, but most bolts are made of carbon steel, alloy steel, or stainless steel. Stainless steels include both iron- and nickel-based chromium alloys. Titanium and aluminum bolts have limited usage, primarily in the aerospace industry. Carbon steel is the cheapest and most common bolt material. Most hardware stores sell carbon steel bolts, which are usually zinc plated to resist corrosion_ The typical ultimate strength of this bolt material is 55 ksi. An alloy steel is a high-strength carbon steel that can be heat treated up to 300 ksi. However, it is not corrosion resistant and must therefore have some type of coating to protect it from corrosion. Aerospace alloy steel fasteners are usually cadmium plated for corrosion protection_ Bolts of stainless steel (cREs) are available in a v