Unit Bearing Pressure for Thread Calculator

✖Axial load on screw is the instantaneous load applied to the screw along its axis.ⓘ Axial load on screw [W_a]			+10% -10%
✖A number of Engaged Threads of a screw/bolt are the count of threads of the screw/bolt that are currently in engagement with the nut.ⓘ Number of Engaged Threads [z]			+10% -10%
✖Nominal diameter of screw is defined as the diameter of the cylinder touching the external threads of the screw.ⓘ Nominal diameter of screw [d]			+10% -10%
✖Core diameter of screw is defined as the smallest diameter of the thread of the screw or nut. The term “minor diameter” replaces the term “core diameter” as applied to the thread of a screw.ⓘ Core diameter of screw [d_c]			+10% -10%

✖Unit bearing pressure for nut is the average pressure acting on the contact surface of the thread in a Screw-Nut pair.ⓘ Unit Bearing Pressure for Thread [S_b]

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Formula

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Unit Bearing Pressure for Thread

Formula

`"S"_{"b"} = 4*"W"_{"a"}/(pi*"z"*(("d"^2)-("d"_{"c"}^2)))`

Example

`"25.18031N/mm²"=4*"131000N"/(pi*"9"*((("50mm")^2)-(("42mm")^2)))`

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Unit Bearing Pressure for Thread Solution

STEP 0: Pre-Calculation Summary

Formula Used

Unit bearing pressure for nut = 4*Axial load on screw/(pi*Number of Engaged Threads*((Nominal diameter of screw^2)-(Core diameter of screw^2)))
S_b = 4*W_a/(pi*z*((d^2)-(d_c^2)))
This formula uses 1 Constants, 5 Variables

Constants Used

pi - Archimedes' constant Value Taken As 3.14159265358979323846264338327950288

Variables Used

Unit bearing pressure for nut - (Measured in Pascal) - Unit bearing pressure for nut is the average pressure acting on the contact surface of the thread in a Screw-Nut pair.
Axial load on screw - (Measured in Newton) - Axial load on screw is the instantaneous load applied to the screw along its axis.
Number of Engaged Threads - A number of Engaged Threads of a screw/bolt are the count of threads of the screw/bolt that are currently in engagement with the nut.
Nominal diameter of screw - (Measured in Meter) - Nominal diameter of screw is defined as the diameter of the cylinder touching the external threads of the screw.
Core diameter of screw - (Measured in Meter) - Core diameter of screw is defined as the smallest diameter of the thread of the screw or nut. The term “minor diameter” replaces the term “core diameter” as applied to the thread of a screw.

STEP 1: Convert Input(s) to Base Unit

Axial load on screw: 131000 Newton --> 131000 Newton No Conversion Required
Number of Engaged Threads: 9 --> No Conversion Required
Nominal diameter of screw: 50 Millimeter --> 0.05 Meter (Check conversion here)
Core diameter of screw: 42 Millimeter --> 0.042 Meter (Check conversion here)

STEP 2: Evaluate Formula

Substituting Input Values in Formula

S_b = 4*W_a/(pi*z*((d^2)-(d_c^2))) --> 4*131000/(pi*9*((0.05^2)-(0.042^2)))

Evaluating ... ...

S_b = 25180311.0447322

STEP 3: Convert Result to Output's Unit

25180311.0447322 Pascal -->25.1803110447322 Newton per Square Millimeter (Check conversion here)

FINAL ANSWER

25.1803110447322 ≈ 25.18031 Newton per Square Millimeter <-- Unit bearing pressure for nut

(Calculation completed in 00.007 seconds)

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Home » Engineering » Mechanical » Machine Design » Power Screws » Design of Screw and Nut » Unit Bearing Pressure for Thread

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Created by Kumar Siddhant

Indian Institute of Information Technology, Design and Manufacturing (IIITDM), Jabalpur

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Osmania University (OU), Hyderabad

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< 25 Design of Screw and Nut Calculators

Nominal Diameter of Screw given Transverse Shear Stress at Root of Nut

Go Nominal diameter of screw = Axial load on screw/(pi*Transverse shear stress in nut*Thread Thickness*Number of Engaged Threads)

Transverse Shear Stress at Root of Nut

Go Transverse shear stress in nut = Axial load on screw/(pi*Nominal diameter of screw*Thread Thickness*Number of Engaged Threads)

Thread Thickness at Core Diameter of Screw given Transverse Shear Stress

Go Thread Thickness = Axial load on screw/(pi*Transverse Shear Stress in Screw*Core diameter of screw*Number of Engaged Threads)

Number of Threads in Engagement with Nut given Transverse Shear Stress

Go Number of Engaged Threads = Axial load on screw/(pi*Thread Thickness*Transverse Shear Stress in Screw*Core diameter of screw)

Core Diameter of Screw given Transverse Shear Stress in Screw

Go Core diameter of screw = Axial load on screw/(Transverse Shear Stress in Screw*pi*Thread Thickness*Number of Engaged Threads)

Axial Load on Screw given Transverse Shear Stress

Go Axial load on screw = (Transverse Shear Stress in Screw*pi*Core diameter of screw*Thread Thickness*Number of Engaged Threads)

Transverse Shear Stress in Screw

Go Transverse Shear Stress in Screw = Axial load on screw/(pi*Core diameter of screw*Thread Thickness*Number of Engaged Threads)

Axial Load on Screw given Transverse Shear Stress at Root of Nut

Go Axial load on screw = pi*Transverse shear stress in nut*Thread Thickness*Nominal diameter of screw*Number of Engaged Threads

Overall Efficiency of Power Screw

Go Efficiency of power screw = Axial load on screw*Lead of Power Screw/(2*pi*Torsional Moment on Screw)

Lead of Screw given Overall Efficiency

Go Lead of Power Screw = 2*pi*Efficiency of power screw*Torsional Moment on Screw/Axial load on screw

Core Diameter of Screw given Direct Compressive Stress

Go Core diameter of screw = sqrt((4*Axial load on screw)/(pi*Compressive stress in screw))

Helix Angle of Thread

Go Helix angle of screw = atan(Lead of Power Screw/(pi*Mean Diameter of Power Screw))

Mean diameter of Screw given Helix Angle

Go Mean Diameter of Power Screw = Lead of Power Screw/(pi*tan(Helix angle of screw))

Lead of Screw given Helix angle

Go Lead of Power Screw = tan(Helix angle of screw)*pi*Mean Diameter of Power Screw

Core Diameter of Screw given Torsional Shear Stress

Go Core diameter of screw = (16*Torsional Moment on Screw/(pi*Torsional shear stress in screw))^(1/3)

Torsional Shear Stress of Screw

Go Torsional shear stress in screw = 16*Torsional Moment on Screw/(pi*(Core diameter of screw^3))

Torsional Moment in Screw given Torsional Shear Stress

Go Torsional Moment on Screw = Torsional shear stress in screw*pi*(Core diameter of screw^3)/16

Direct Compressive Stress in Screw

Go Compressive stress in screw = (Axial load on screw*4)/(pi*Core diameter of screw^2)

Axial Load on Screw given Direct Compressive Stress

Go Axial load on screw = (Compressive stress in screw*pi*Core diameter of screw^2)/4

Nominal Diameter of Power Screw given Mean Diameter

Go Nominal diameter of screw = Mean Diameter of Power Screw+(0.5*Pitch of power screw thread)

Pitch of Screw given Mean Diameter

Go Pitch of power screw thread = (Nominal diameter of screw-Mean Diameter of Power Screw)/0.5

Mean Diameter of Power Screw

Go Mean Diameter of Power Screw = Nominal diameter of screw-0.5*Pitch of power screw thread

Nominal Diameter of Power Screw

Go Nominal diameter of screw = Core diameter of screw+Pitch of power screw thread

Core Diameter of Power Screw

Go Core diameter of screw = Nominal diameter of screw-Pitch of power screw thread

Pitch of Power Screw

Go Pitch of power screw thread = Nominal diameter of screw-Core diameter of screw

Unit Bearing Pressure for Thread Formula

Unit bearing pressure for nut = 4*Axial load on screw/(pi*Number of Engaged Threads*((Nominal diameter of screw^2)-(Core diameter of screw^2)))
S_b = 4*W_a/(pi*z*((d^2)-(d_c^2)))

Permissible Bearing Pressure

The permissible bearing pressure depends upon the materials of the screw and the nut and the rubbing velocity. It is the maximum Bearing Pressure that is allowed on the structure, considering the factor of safety.

How to Calculate Unit Bearing Pressure for Thread?

Unit Bearing Pressure for Thread calculator uses Unit bearing pressure for nut = 4*Axial load on screw/(pi*Number of Engaged Threads*((Nominal diameter of screw^2)-(Core diameter of screw^2))) to calculate the Unit bearing pressure for nut, The Unit Bearing Pressure for Thread is the average pressure per thread acting on the contacting surface of the thread in a Screw-Nut pair. It is an important consideration for design applications. Unit bearing pressure for nut is denoted by S_b symbol.

How to calculate Unit Bearing Pressure for Thread using this online calculator? To use this online calculator for Unit Bearing Pressure for Thread, enter Axial load on screw (W_a), Number of Engaged Threads (z), Nominal diameter of screw (d) & Core diameter of screw (d_c) and hit the calculate button. Here is how the Unit Bearing Pressure for Thread calculation can be explained with given input values -> 2.5E-5 = 4*131000/(pi*9*((0.05^2)-(0.042^2))).

FAQ

What is Unit Bearing Pressure for Thread?

The Unit Bearing Pressure for Thread is the average pressure per thread acting on the contacting surface of the thread in a Screw-Nut pair. It is an important consideration for design applications and is represented as S_b = 4*W_a/(pi*z*((d^2)-(d_c^2))) or Unit bearing pressure for nut = 4*Axial load on screw/(pi*Number of Engaged Threads*((Nominal diameter of screw^2)-(Core diameter of screw^2))). Axial load on screw is the instantaneous load applied to the screw along its axis, A number of Engaged Threads of a screw/bolt are the count of threads of the screw/bolt that are currently in engagement with the nut, Nominal diameter of screw is defined as the diameter of the cylinder touching the external threads of the screw & Core diameter of screw is defined as the smallest diameter of the thread of the screw or nut. The term “minor diameter” replaces the term “core diameter” as applied to the thread of a screw.

How to calculate Unit Bearing Pressure for Thread?

The Unit Bearing Pressure for Thread is the average pressure per thread acting on the contacting surface of the thread in a Screw-Nut pair. It is an important consideration for design applications is calculated using Unit bearing pressure for nut = 4*Axial load on screw/(pi*Number of Engaged Threads*((Nominal diameter of screw^2)-(Core diameter of screw^2))). To calculate Unit Bearing Pressure for Thread, you need Axial load on screw (W_a), Number of Engaged Threads (z), Nominal diameter of screw (d) & Core diameter of screw (d_c). With our tool, you need to enter the respective value for Axial load on screw, Number of Engaged Threads, Nominal diameter of screw & Core diameter of screw and hit the calculate button. You can also select the units (if any) for Input(s) and the Output as well.

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