fiber to fiber and fiber to metal friction

FIBER TO FIBER AND FIBER TO METAL FRICTIONBy:

Muhammad Khalil Azher

11-NTU-6011

04/07/2023 Fiber to Fiber and Fiber to Metal Friction 2


Friction• Friction is the force resisting the relative motion of solid

surfaces, fluid layers, and material elements sliding against each other.


Importance of Friction• Hand, aesthetics, and performance of end-use products

are related to the frictional properties of the fabric. • For instance, high friction is preferable for shirts, while low

friction is needed for lining materials.


Yarn to Yarn and Yarn to Metal Friction

• Yarn-to-metal friction, yarn-to-air friction, and friction between and within yarns determine yarn behaviours during processing.

• The coefficients of yarn-to-yarn and yarn-to-metal friction are of importance in that they determine the tensions in the threads, though they do not directly reflect the effects of friction observed.


Types of friction1. Dry friction resists relative lateral motion of two solid

surfaces in contact. Dry friction is subdivided into static friction between non-moving surfaces, and kinetic friction between moving surfaces.

2. Fluid friction describes the friction between layers within a viscous fluid that are moving relative to each other.

3. Lubricated friction is a case of fluid friction where a fluid separates two solid surfaces.

4. Skin friction is a component of drag, the force resisting the motion of a solid body through a fluid.

5. Internal friction is the force resisting motion between the elements making up a solid material while it undergoes deformation.


More about Friction• Friction is not a fundamental force but occurs because of

the electromagnetic forces between charged particles which constitute the surfaces in contact. Because of the complexity of these interactions, friction cannot be calculated from first principles, but instead must be found empirically.


Dry friction• Dry friction resists relative lateral motion of two solid

surfaces in contact. • The two regimes of dry friction are 'static friction' between

non-moving surfaces, and kinetic friction (sometimes called sliding friction or dynamic friction) between moving surfaces.


• Coulomb friction, named after Charles-Augustin de Coulomb, is an approximate model used to calculate the force of dry friction.

• It is governed by the equation:


Co efficient of Friction

• The coefficient of friction (COF), often symbolized by the Greek letter µ, is a dimensionless scalar value which describes the ratio of the force of friction between two bodies and the force pressing them together.

• The coefficient of friction depends on the materials used; for example, ice on steel has a low coefficient of friction, while rubber on pavement has a high coefficient of friction.

• Coefficients of friction range from near zero to greater than one – under good conditions, a tire on concrete may have a coefficient of friction of 1.7.

http://en.wikipedia.org/wiki/Mu_(letter)


Static friction• Static friction is friction between two or more solid objects

that are not moving relative to each other.• The maximum possible friction force

between two surfaces before sliding begins is the product of the coefficient of static friction and the normal force:

• When there is no sliding occurring, the friction force can have any value from zero up to .


Energy of friction• According to the law of conservation of energy, no energy

is destroyed due to friction, though it may be lost to the system of concern. Energy is transformed from other forms into heat.

• When an object is pushed along a surface, the energy converted to heat is given by:


Cross sectional Shapes


Fiber Friction in Different Fibers• Wool has greater friction as compared to other natural

fibers due to it’s scaly surface.


Friction in flax fiber• Flex has less friction


Cotton


Cotton vs Wool• Cotton has greater convolutions and wool has greater

crimp.


Silk• Silk fiber has lowest fiber to fiber and fiber to metal friction

due to its regular shape.


Importance of Fiber Friction• Fiber friction is very important due to:• Comfort properties relate to the fiber-skin friction• Fabric friction is important in it’s appearance and

performance (pilling).


Measurement of Fiber Friction• Frictionometer: It is made from a single piece of steel,

measuring 12 cm x 15 cm x 2.5 cm.


Multipurpose Friction Tester


Frictionometer made by Custom Scientific Inst. Model 131-086


Measurement


Test Procedure


Test Materials


GM-1 Tester


• GM-1 Coefficient of Friction Tester mainly measure the smoothness property of OPP,PET,NILON,CPP,CPE and other plastic materials and sheets .

• By testing the friction efficient number judges the smoothness, uniformity of film, efficiently to prevent it’s smoothness level avoiding the quality defects.

• It’s used in packaging field, film factory, printing industry, paper factory, packaging test institutions.

• It carries the standard of GB 10006 -1988, ASTM D 1894 -1990 ,TAPPI 816 wd-00,ISO 8295 -1995.


Another Friction Tester


Friction Materials and Uses• Organic woven metal-fiber delivers smooth engagement

and is the choice of original-equipment when it comes to clutch disc friction material. It requires minimal-to-no break in period.

• This material can overheat with repeated abuse.• Kevlar is a highly durable material that has similar

engagement characteristics as organic. • When segmented, Kevlar provides better heat dissipation.

This material requires a 500 to 800 miles break in period.


• Ceramic is a very high temperature resistant material. It's generally utilized in puck style disc for high horsepower and race applications. This material will wear flywheel surfaces faster than organic and Kevlar, especially in stop and go traffic situations.

• Feramic is an extremely high temperature resistant material. It has the best friction coefficient at high temperature.

• The engagement is more aggressive than ceramic and is harsher on the flywheel surface.

• When contaminated with oil or grease, this material can fuse to the flywheel or pressure plate's riding surface. This material is only available on custom orders.


Fabric-to-Metal Friction• The relationship between the frictional force and normal

load is found to be logarithmic, as was found by Wilson:

(F/A) = k (N/A) n or, log (F/A) = log k + n log (N/A)• where, A is the area of contact, k is the friction parameter

and n is the friction index.


Adhesion Theory of Friction• This relation can be explained using the adhesion theory

of friction. • According to this theory, with the increase in the normal

pressure, there will be a reduction in the true area of contact.


PET vs PC• The fabric-to-metal friction in the case of 100% polyester

is lower than the polyester/cotton blended fabrics. • This may be due to the fact that the yarn becomes fuzzier

with the addition of the cotton component. • These surface fibres will offer more resistance to the

motion.


• The relationships between normal load and fabric to the metal frictional force for polyester & polyester/cotton blended fabrics and viscose & viscose/polyester blended fabrics are shown in Figures next.


Fibre Surface Roughness• It has been observed that with an increase in roughness

of the fibre surface, final tension and hence friction in the yarn increases.


THANKS

fiber to fiber and fiber to metal friction

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