What is the definition of "proof load"?
The tension-applied load that a fastener must support without evidence of deformation. Proof load is often used interchangeably with yield strength.

Learn more about proof load in the class Threaded Fastener Selection 215 below.


Fasteners Training


Class Information
Fasteners Training Tooling U-SME classes are offered at the beginner, intermediate, and advanced levels. The typical class consists of 12 to 25 lessons and will take approximately one hour to complete.
Class Name:Threaded Fastener Selection 215
Description:This class describes how to select a threaded fastener as well as how to install a bolt and nut combination into a joint.
Prerequisites: 700117  700120  700125 
Difficulty:Intermediate
Number of Lessons:18
Language:English, Spanish
 
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Class Outline
  • Objectives
  • The Importance of Fastener Selection
  • Identifying Fasteners
  • Head Styles
  • Driving Recess
  • Point Styles
  • Common Bolt Types
  • Fastener Materials
  • Fastener Diameter
  • Fastener Length and Size
  • English and Metric Fastener Identification
  • Strength Grade Systems
  • Identification Markings
  • Bolted Joint Characteristics
  • Nut Selection
  • Washer Selection
  • Bolt Installation
  • Summary
  
Class Objectives
  • Explain the importance of fastener selection.
  • Describe how fasteners are identified.
  • Identify common fastener head styles.
  • Identify common types of driving recesses.
  • List common point styles.
  • Identify common bolt types.
  • Describe common fastener materials.
  • Describe how fastener diameter is measured.
  • Describe how to determine a fastener's length.
  • Describe how to determine a fastener's size.
  • Describe how to identify an English fastener.
  • Describe how to identify a metric fastener.
  • Describe the strength grade systems for English and metric fasteners.
  • Describe identification markings for English and metric fasteners.
  • Describe the characteristics of a bolted joint.
  • Identify nuts according to their strength grade.
  • Describe factors to consider for proper washer selection.
  • Describe how to install a bolt.

Class Vocabulary

Vocabulary TermDefinition
alloy steel A type of steel that contains another material that is added intentionally to improve the properties of the metal.
aluminum A silvery, white metal that is soft, light and is electrically and thermally conductive.
bearing surface The circular underside of the bolt head that makes contact with the part.
binding head A type of head that is similar to the pan head but much thicker with a deeper slot.
bolt A cylindrically shaped, threaded device used for fastening parts. Bolts usually have blunt ends and mate with a nut.
bolt stretch The amount of tension in a bolt after the wrench has been removed. Bolt stretch determines the strength of the bolted joint.
bolted joint Two pieces of metal joined together by the use of threaded fasteners.
brass A nonferrous alloy containing copper and zinc. Brass has high tensile strength and corrosion resistance.
carbon steel A type of steel made up of iron and carbon and no other material. Most fasteners are made from carbon steel.
carriage bolt A type of bolt with a round head and a square neck that prevents the bolt from turning while the nut is tightened.
chamfer point A type of point that is similar to a pilot point. A chamfer point also has a truncated end to help the assembler guide the fastener into the hole.
cheese head A type of head that is very thick allowing for a deep slot for increased driving power.
clamping force The compressive force that a fastener exerts on a joint.
clock system A system that identifies the strengths of nuts.
cold working The shaping of metal at temperatures much lower than the metal's molten state.
cone point A type of point with a cone shape that allows for deep penetration and is used for permanent location of parts
conical washer A type of spring washer used with screws to increase the elastic properties of a joint.
copper A reddish-brown metal that is very ductile, thermally and electrically conductive, and corrosion resistant. Copper fasteners are often used for electrical components.
corrosion resistant The ability of a material to resist chemical destruction from an environment. Corrosion resistance is the most important physical property for fasteners.
counter-bored hole A hole that has been enlarged to accept a bolt so that it can be seated flush with or below the surface.
countersinking The cutting of a beveled edge at the end of a hole so that the head of a fastener can rest flush with the workpiece surface.
cross threading A condition that occurs when a rotating fastener is misaligned with a tapped hole.
dome-head bolt A type of bolt with a round head above the wrench flats.
driving recess The shape on the top of a fastener head designed to accept a particular tool.
electrical conductivity The ability of a material to conduct an electrical current.
environmental resistance The ability of a fastener to resist forces in the environment that attempt to deform it.
fastener A device that holds two or more objects together. A fastener can be a bolt or a screw as well as a button or a zipper.
fastener diameter The distance between certain points on a fastener. Fastener diameter is measured using the shank, thread, and root of the fastener.
fastener length A measurement of a fastener based on its head style. Generally, fastener length is measured from the underside of the head to the tip of the fastener.
fastener type A category that indicates the function and design of a fastener. A wood screw is a fastener type categorized by the material it fastens.
fatigue life The length of time a thread lasts before breaking down or failing.
faying surfaces Two surfaces which lie close together or fit together.
fillister head A type of head that is similar to the cheese head but with a rounded top for better appearance.
flat head A type of head that is flat in shape and is used in countersunk holes.
flat point A type of point with a blunt end used where parts must be frequently re-set.
flat washer A type of washer that is slighly oversized allowing it to slide easily over the bolt.
flat-head screw A type of screw that has a flat-shaped head style.
Frearson A type of driving recess similar to Phillips but with less tapered slots.
gimlet point A type of point with a sharp tip used for penetrating wood.
grade A category, rank, or level of quality. Bolts are classified by grades.
Grade 2 An inch series strength grade that has no slash marks and is used for low-carbon steels.
Grade 5 An inch series strength grade that has three slash marks and is used for medium-carbon steels that have been quenched and tempered.
Grade 8 An inch series strength grade that has six slash marks and is used for alloy steels that have been quenched and tempered.
grip length The length of the unthreaded portion of the bolt shank.
head style The shape of the fastener head. There are many different head styles for fasteners.
hex bolt A type of bolt that has a head with six sides.
hex key A small, hexagonal-shaped wrench designed to be used with socket head cap screws.
hex socket A type of driving recess with a hexagonal indentation designed to accept an Allen wrench.
hexagonal head A type of head that has six sides. A hex head is the standard head style for machine bolts and screws.
hex-washer head A type of head that is similar to the hex head except with a washer at the base.
identification marking A marking on a fastener that often indicates the maker of the part and/or the manufactured fastener capability.
lag bolt A heavy-duty wood screw that has a square or hexagonal head so they can be turned with a wrench.
low-carbon steel A type of carbon steel that contains less than 0.3% carbon. Grade 2 fasteners are common low-carbon steel fasteners.
major diameter Another name for thread diameter.
material type A category that indicates the material from which a fastener is made as well as its grade. Carbon steel is the most common material type.
medium-carbon steel A type of carbon steel that contains between 0.3% and .05% carbon. Grade 5 fasteners are common medium-carbon steel fasteners.
megapascal The metric unit of pressure. Megapascal is abbreviated Mpa.
minor diameter Another name for root diameter.
nonferrous metal A metal that does not contain iron. Aluminum, copper, and zinc are nonferrous metals.
oval head A type of head that is oval in shape and is used when appearance matters.
oval point A type of point with an oval-shaped end used for frequent adjustment without deforming the part's bearing surface.
pan head A type of head that is wide and provides great clamping strength. Pan heads are unattractive and are often used where they will not be seen.
Phillips A type of driving recess that has an X-shaped indentation designed to accept a Phillips screwdriver.
pilot point A type of point that has a truncated end to help the assembler guide the fastener into the hole.
plow bolt A square-head bolt often used on heavy construction equipment.
point style The shape of a fastener point. Point style controls the amount of material penetration or alignment.
Pozidriv A type of driving recess that has an X-shaped indentation with a star-like shape on top designed to accept Pozidriv screwdrivers.
proof load The tension-applied load that a fastener must support without evidence of deformation. Proof load is often used interchangeably with yield strength.
property classes A designation system that defines the strength of metric fasteners. These designations consist of numbers where increasing numbers represent increasing tensile strengths.
quenched The state of the cooling of metal rapidly by using water, air, or oil.
radial line A line on the surface of a nut that extends out like a circle radius.
Robertson A type of driving recess that has a square-shaped indentation designed to accept a special power-tool bit or screwdriver.
root diameter The distance between the roots of a thread. Root diameter is the smallest diameter on a thread.
round head A type of head that is round in shape and sits flush against a surface.
screw A threaded device used for fastening parts or transferring motion. Screws usually have pointed ends.
shank diameter The diameter that is measured on the shank of the fastener. Shank diameter is approximately the same as thread diameter.
sheet metal screw A type of screw with a sharp, pointed end and sharp threads for penetrating sheet metal.
size number A number assigned to indicate the measurement of a fastener's diameter.
slotted A type of driving recess that has as straight-line slot designed to accept a flat-blade screwdriver.
Society of Automotive Engineers An organization of engineers that sets most industry standards for the testing, measuring, and designing of automobiles and their components.
socket head cap screw A type of cap screw with a round head and a hexagonal indentation for tightening purposes.
stainless steel A type of steel that contains more than 15% chromium and exhibits excellent corrosion resistance.
structural bolt A heavy type of hex bolt intended for use in large structures, such as buildings and bridges.
tapped hole A type of hole that contains internal threads created by forming or cutting.
tempered The state of the hardening of a metal by the use of heat treatment.
tensile strength The ability of a material to resist forces that attempt to pull it apart or stretch it.
thread diameter The distance between the crests of a thread. Thread diameter is the widest diameter on a thread.
thread gage A measuring instrument used to inspect the internal threads of a part.
thread pitch The distance from one thread groove to the next, measured from crest to crest.
torque The amount of force applied to tighten a threaded fastener.
Torx A type of driving recess that has a six-lobed indentation designed to accept Torx screwdrivers.
truss head A type of head that is similar to the pan head but with a shallower head and rounded on top.
twelve-point bolt A type of bolt with a double hexagon head. Twelve-point bolts are high-strength fasteners often used in the aircraft industry.
washer A flat disc with a hole through the center that is often used with threaded fasteners to ensure joint tightness.
weight-to-strength ratio The weight of an object divided by its strength. Twelve-point bolts have a low weight-to-strength ratio.
wood screw A type of screw with a sharp, pointed end and a tapered shank with sharp threads for penetrating wood. Wood screws come in a variety of styles.
wrench flats A flat surface beneath the fastener head that facilitates tightening with a wrench.
yield strength The load at which a fastener experiences a specified amount of permanent deformation.