Transcript Fasteners - Shenendehowa Central Schools

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.
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Material
Diameter
Pitch/Thread
Head Shape
Finish
Class
Grade
Material
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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
Correct Pitch Gauge
Incorrect Pitch Gauge
Class

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Class
Class
Class
Class
1
2
3
4
=
=
=
=
Loose
Free
Medium
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.
Bolt Identification
Metric Bolt Identification
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
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Flat
Split
Toothed
Insulating
Common Washers
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
Torque Angle Gauge
Torque to Yield Graph
The End