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Fasteners. Mr. Lombardi. Fasteners. There are many different types of fasteners. Screws, Nuts, Bolts, etc. Each one performs specific task best accomplished by that specific fastener. Screws. A headed threaded fastener that is designed to be used by forming its own threads. . Bolts.
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Fasteners Mr. Lombardi
Fasteners • There are many different types of fasteners. • Screws, Nuts, Bolts, etc. • Each one performs specific task best accomplished by that specific fastener.
Screws • A headed threaded fastener that is designed to be used by forming its own threads.
Bolts • A bolt is the term used for a headed fastener having external threads that meet an exacting, uniform bolt thread specification
Nuts • A nut is a type of hardware fastener with a threaded hole. • Along with a bolt, nuts are designed to capture and fasten objects together.
Cotter Pin • A metal fastener with two tines that are bent during installation, similar to a staple or rivet
Retaining Ring • A small circular steel ring, often resembling the letter "C," that is usually inserted into a slot in a pivot pin to hold the pin in a specified position.
Wing Nuts / Thumb Screws • A nut that can be tightened or removed without tools by turning it with fingers
Classification • There are 7 descriptors for every bolt. • Material • Diameter • Pitch/Thread • Head Shape • Finish • Class • Grade
Material • Steel • Stainless Steel • Brass • Etc.
Diameter • T – Thread Diameter • R – Root Diameter (minor) • S – Shank Diameter
Thread / Pitch • Measured in TPI (threads per inch)
Pitch • Thread Pitch is measured with a special gauge
Class • Class 1 = Loose • Class 2 = Free • Class 3 = Medium • Class 4 = Close • Most are class 2. 3 is for precision assembly, and 4 is used for things like lathe lead screws and measuring instruments.
Head Shape • Many, many shapes and sizes
Hardware Grade • The grade tells the strength of the fastener. • Nuts and Bolts must be the SAME grade.
Grades (US) • Grade 2 – 74,000psi • Grade 5 – 120,000psi • Grade 8 – 150,000psi
Grade 2 • Zinc plated low carbon steel. Best for general hardware use where high strength is not required.
Grade 5 • Made from medium carbon steel, tempered and zinc plated. Best for automotive use and other areas where higher strength is desired.
Grade 8 • Made from medium carbon alloy steel, tempered, and zinc plated. Best suited for applications where high strength and hardness is required.
Grades (Metric) • Grade 8.8 • Grade 10.9
Grade8.8 • Made from medium carbon steel and zinc plated. Best for general hardware use where high strength is not required. Standard metric thread pitches.
Grade 10.9 • Made from alloy steel quenched, tempered, and zinc plated. Best for automotive use and other areas where high strength is needed.
Common Nuts L to R: Wing, hex, hex flange, and flanged weld (for stud welding) nuts.
More Common Nuts L to R: Slotted, square, T, cap (or acorn), nylon locking, and castellated nuts
Washers • Four Common Types • Flat • Split • Toothed • Insulating
Torque To Yield Bolts (TTY) • They are tightened (torqued) until they just begin to stretch • This provides a very consistent clamping load and helps keep an even sealing pressure for the items being fastened
Torque to Yield bolts require special procedures • Tighten to the specified torque • Continue to turn the fastener just enough to cause it to begin to stretch • This will be specified in degrees of rotation