![Stud bolt 1](https://upload.wikimedia.org/wikipedia/commons/9/9b/Stud_bolt_1.jpg)
A threaded rod, also known as a stud, is a relatively long rod that is
threaded on both ends; the thread may extend along the complete length of the rod. They are designed to be used in
tension
Tension may refer to:
Science
* Psychological stress
* Tension (physics), a force related to the stretching of an object (the opposite of compression)
* Tension (geology), a stress which stretches rocks in two opposite directions
* Voltage or el ...
. Threaded rod in
bar stock
Bar stock, also (colloquially) known as blank, slug or billet, is a common form of raw purified metal, used by industry to manufacture metal parts and products. Bar stock is available in a variety of extrusion shapes and lengths. The most commo ...
form is often called all-thread.
Studs
![Motore Balilla PSF](https://upload.wikimedia.org/wikipedia/commons/f/ff/Motore_Balilla_PSF.jpg)
Studs may have a
drive
Drive or The Drive may refer to:
Motoring
* Driving, the act of controlling a vehicle
* Road trip, a journey on roads
Roadways
Roadways called "drives" may include:
* Driveway, a private road for local access to structures, abbreviated "drive"
...
slot in one end to facilitate installing the stud.
Types
With respect to shape, stud bolts a.k.a. studs are categorized into three basic types: "fully threaded stud bolts", "tap-end stud bolts", and "double-end stud bolts". Each of these studs have different application. As name suggests, fully threaded studs have full body coverage with threads for full engagement of the matings
nuts or similar parts. Tap-end studs have threads at extreme ends of the body with unequal thread engagement length, while double-end stud bolts have equal thread length at both ends. Apart from these, there are stud bolts for
flange
A flange is a protruded ridge, lip or rim (wheel), rim, either external or internal, that serves to increase shear strength, strength (as the flange of an iron beam (structure), beam such as an I-beam or a T-beam); for easy attachment/transfer of ...
s, which are fully threaded studs with chamfered ends, and double-end studs with reduced shank for special bolting applications.
For studs that are not completely threaded, there are two types of studs: ''full-bodied'' studs, and ''undercut'' studs. Full-bodied studs have a shank equal to the
major diameter of the thread.
Undercut
Undercut may refer to:
* Price slashing, a pricing technique designed to eliminate competition
*Undercut procedure, a procedure for fair allocation of indivisible objects.
* Undercut (boxing), a type of boxing punch
* ''Undercut'' (film), a stunt ...
studs have a shank equal to the
pitch diameter of the screw thread. Undercut studs are designed to better distribute axial
stresses. In a full-bodied stud the stresses are greater in the threads than in the shank.
Undercut studs (rolled thread) are also stronger because the metal is "rolled" up to the major diameter, not removed. This preserves the
grain
A grain is a small, hard, dry fruit (caryopsis) – with or without an attached hull layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are cereals and legum ...
of the steel, and in some cases even enhances it. Full-bodied studs (cut thread) are weaker because metal is removed to create the thread, disturbing the grain of the steel.
Undercut studs are only required in applications where the stud is exposed to fatigue. Cut threads are entirely suitable for many applications, even when rolled threads might be slightly stronger. Mass-produced fasteners (standard bolts and studs) are usually rolled, but
jobbed parts with custom features and small lot sizes are likely to be cut.
Strength
The allowable tensile force for a non-undercut threaded rod is defined by the
American Institute of Steel Construction
The American Institute of Steel Construction (AISC) is a not-for-profit technical institute and trade association
A trade association, also known as an industry trade group, business association, sector association or industry body, is an or ...
(AISC) as
:
where ''d'' is the nominal diameter, and ''F''
u is the
ultimate tensile strength
Ultimate tensile strength (UTS), often shortened to tensile strength (TS), ultimate strength, or F_\text within equations, is the maximum stress that a material can withstand while being stretched or pulled before breaking. In brittle materials t ...
of the material. For undercut threaded rods the allowable tensile stress is defined as
:
where ''d''
s is the diameter of the shank, and ''F''
y is the
yield strength
In materials science and engineering, the yield point is the point on a stress-strain curve that indicates the limit of elastic behavior and the beginning of plastic behavior. Below the yield point, a material will deform elastically and wi ...
of the material.
Both equations give units of force for the result, i.e.
pounds-force
The pound of force or pound-force (symbol: lbf, sometimes lbf,) is a unit of force used in some systems of measurement, including English Engineering units and the foot–pound–second system.
Pound-force should not be confused with pound-ma ...
or
newtons
The newton (symbol: N) is the unit of force in the International System of Units (SI). It is defined as 1 kg⋅m/s, the force which gives a mass of 1 kilogram an acceleration of 1 metre per second per second. It is named after Isaac Newton in r ...
.
Class
Metric threaded rods are marked on the end with a color code to define the
ISO
ISO is the most common abbreviation for the International Organization for Standardization.
ISO or Iso may also refer to: Business and finance
* Iso (supermarket), a chain of Danish supermarkets incorporated into the SuperBest chain in 2007
* Iso ...
strength class. The color codes are:
bomet.com
/ref>
*Unmarked — 4.6 class (tensile strength
Ultimate tensile strength (UTS), often shortened to tensile strength (TS), ultimate strength, or F_\text within equations, is the maximum stress that a material can withstand while being stretched or pulled before breaking. In brittle materials t ...
= 400 N/mm2, yield strength
In materials science and engineering, the yield point is the point on a stress-strain curve that indicates the limit of elastic behavior and the beginning of plastic behavior. Below the yield point, a material will deform elastically and wi ...
240 N/mm2)
*Yellow — 8.8 class (800 N/mm2, 640 N/mm2)
*Green — A2 stainless steel (304)
*Red — A4 stainless steel (316)
*White — 10.9 class (1000 N/mm2, 900 N/mm2)
References
Bibliography
* {{MachinerysHandbook25e
Threaded fasteners