# Mechanics of Screw Threads ...Web page include screw friction values

A self-holding 'Taper' is an accurately machined tapering shaft and mating sleeve (both of which are dry and clean) that lock together using the coefficient of friction between the two surfaces (shaft and sleeve) and an assembly force (F). If the Taper is machined correctly, the same force (F) will be needed to separate the shaft and sleeve.

## E.g.: For a coefficient of friction of 1.0 this angle is 45°

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### For values of rolling bearing friction

The friction coefficient calculator gives you the option of selecting a recommended (by CalQlata) coefficient of friction via a series of material combination options or you may enter your own independent value. Whilst will accept any value for '' in accordance with our '' principal, values less than or equal to 0 will result in failed calculations or negative angles, and values for '' greater than 3, whilst theoretically correct, will usually give unrealistic results.

### For values of rolling bearing friction

Whilst Morse's Taper was originally designed for carbon steel surfaces ( = 0.8), the friction coefficient calculator can predict the angle of a Taper manufactured for any coefficient of friction, i.e. any material combination and surface condition but with the same self-holding capacity as Morse's Taper of the same Grade.

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## Coefficients of friction of various materials

The coefficient of friction value is important in the design and brakes and clutches.

Various values are provided on the following linked page

## Coefficients of friction between cereal grain and …

The coefficient of friction is required in calculating tightening torques and resultingbolt tensile forces and stress and in calculating the resulting friction between the connectedsurfaces. Below are provided a small number of values showing approximatevalues of friction coefficients to be used for steel screw fastened connections. The values are only representative values and should be confirmed against other sources ofinformation and preferably testing.

## Coefficients of Friction for Steel - The Physics Factbook

** Plain Bearing Friction factors**

For values of rolling bearing friction ** Rolling Bearing Friction**

For values of rolling bearing friction ** Clutch - Brake Friction Values**

The coefficient of friction value is important in the design and brakes and clutches.

Various values are provided on the following linked page ** Friction coefficient Bolted Joints**

The coefficient of friction is required in calculating tightening torques and resultingbolt tensile forces and stress and in calculating the resulting friction between the connectedsurfaces. Below are provided a small number of values showing approximatevalues of friction coefficients to be used for steel screw fastened connections. The values are only representative values and should be confirmed against other sources ofinformation and preferably testing.

Coefficient of Friction for screw threads

Coefficient of Friction Nut/Bolt Face against Clamped surface Coefficient of friction between surfaces clamped by bolts /screws.

These values allow calculation of the shear force necessary to cause slip betweensurfaces when clamped by bolts.