Introduction to Fastener Technology Part 3 An Aerospace Manufacturing Perspective

Fasteners in Aviation Permanent Fastening Temporary Fastening Discussed previously Temporary Fastening Threaded Non-Threaded

Temporary Fastening Threaded Bolts Studs Screws Non - Threaded

Threaded Fasteners Use to hold parts together Unlike any other fasteners, threaded fasteners are able to move part(s) relative to others

Thread Terminology External (male) thread: Thread cuts outside of the cylindrical body. Internal (female) thread: Thread cuts inside of the cylindrical body.

Thread Terminology Crest – Peak edge of thread Root – Bottom of thread cut into a cylindrical body Thread angle – Angle between threads faces

Thread Terminology Major diameter – Largest diameter on an external or internal thread Minor diameter – Smallest diameter on an external or internal thread

Thread Terminology Pitch – Distance between crests of threads

Types of Thread Form Profile shape of the thread

Thread Standard A metric ISO screw thread is designated by the letter M followed by the value of the nominal diameter D and the pitch P, both expressed in millimeters and separated by the multiplication sign “×”. Example: M8×1.25

Thread Drawings For simplified representation, use thick and thin continuous lines for representing crests and roots respectively:

Bolt Terminology Bolt is a threaded cylinder with a head

Bolt Application

Screw Terminology Screw is similar to bolt, but has a longer thread than a bolt Bolted joint is usually created by turning a nut; screw is installed by turning it.

Screws Application

Stud Terminology

Stud Application