Abrasion

Wearing away by rubbing, scraping. Video. The established abrasion tests, for instance as per ISO 4649, have practical relevance only for grinding kind of applications. The abrasion value alone is no indicator of a belt's wear resistance.

Adhesion

The bonding strength between two materials.

Afterglow

The red glow persisting after extinction of the flame, for instance in certain fire resistance tests.

Aging

The exposure to an environment for a period of time.

Antioxidant

A compound ingredient used to retard deterioration caused by oxygen.

Antistatic

Code letter E as per DIN 22102 and 22131. Grades K, S and V have a surface resistivity of min. 300 MOhm. Tested as per DIN 22104.

Aramide

Stands for aromatic polyamide. Its acronym is D. Aramide is a low elongation, light, high-strength fiber with limited applicability for conveyor belts because of its poor fatigue properties and sensitivity to chafing. Expensive. Loses strength under UV radiation (splicing!). Trademarks are Kevlar and Twaron.

Arc of contact

The circumferential portion of a pulley which is engaged by a belt.

ARPM

Association for Rubber Products Manufacturers, a successor of RMA. Published their conveyor belt handbook in 2011, determining grade 1 with tensile strength of 17 MPa, elongation at break of 400 % and volume loss of 125 mm³.

Belt clamp

Beams or metal plates secured transversely to hold the belt in a desired position.

Belt cleaning device

A scraper or rotating device pressed against the belt surface to remove material stuck to the belt.

Belt fastener

A device for holding two ends of a conveyor belt together. More.

Belt grade

A classification of the rubber quality and properties as per ISO, DIN or other standards. More...

Belt marking

Usually, every belt length has an embossed individual serial number, plus the belt type and the manufacturer's acronym. The size and positioning of the marking can be agreed between customer and manufacturer. Example

Belt modulus

The force per unit width of belt required to produce a stated percentage of elongation, or the ratio of stress to strain. See "Modulus of elasticity".

Belt sag

The amount of vertical deflection of a conveyor belt from a straight line between idlers, usually expressed as a percentage of the center to center spacing of the idlers.

Belt slip

The speed differential between the belt and the pulley surface, accelerating the abrasion of the belt cover.

Belt tear resistance

Or "tear propagation resistance". A belt sample is cut and then further separated. Odditiy: as per ISO 505, the parties must decide with order placement, whether the minimum value required is related to a test with or without belt covers.

Belt tension

See "tension".

Belt training idler

An idler having a belt-actuated swivel mechanism to automatically control side drifting of a conveyor belt.

Belt turnover

A system of idlers to turn a belt over (upside down). Illustration.

Belt weight

See Chart.

Belt width

Wherever possible, standard widths (for instance 1000, 1200, 1400 mm etc.) should be chosen, so they fit to other standardized conveyor components.

Bending modulus

The force required to induce bending around a specified radius and, hence, a measure of stiffness.

Bend pulley

A pulley used to change the direction of a belt.

Bias cut

A cut of belt ends made diagonally at an angle less than 90 degrees - usually 30° - to the longitudinal axis. Video.

Binder warp yarn

One of the warp systems in a straight warp fabric interlaced with the filling yarn to provide the strength to hold mechanical fasteners.

Bleeding

Migration to the surface of plasticizer, waxes or similar materials to form a film or beads.

Blister

A raised spot on the surface or a separation between layers usually forming a void or air-filled space in the vulcanized conveyor belt.

Booster drive

Used in some long conveyors to reduce the power/tension at the drive pulley.

Bottom cover

The non-carrying belt side towards the pulleys. Usually thinner than the top cover.

Bow

A bow is a longitudinal curve in a belt on its concave side. A bow can be created during manufacture, improper storing, splicing or tensioning. See also Camber.

Breaker

An extra ply made of fabric or steel for shock absorption to minimize gouging.

Breaking strength

The breaking strength of the conveyor belt, either nominal/minimum (e.g. St 2000) or ultimate/actual (e.g. 2197 N/mm). Test

Bucket elevator belt

A transversely rigid belt with buckets attached, for vertical conveying.

Bulk density

Required for determining the troughing angle, the angle of repose and maximum inclination. Table.

Butt gap

The distance between two opposing steel cords in a conveyor belt splice.

Calender

A roller mill equipped with three or more internally heated or cooled drums, used to continuously sheet out polymeric compound to wipe it into the interstices of a fabric leaving a small portion of it on the surface of the fabric, or to lay a continuous sheet of compound on a fabric. More...

Camber

Describes a crooked conveyor belt ("banana"). More...

Capacity

The material load on the belt, given in tons per hour (t/h). More...

Carbon black
Carbon black is used to increase strength and abrasion resistance of a rubber compound. Smaller particles provide better reinforcement but are more difficult to process. The Chinese used carbon black 500 years ago to make ink and lacquer.

Carcass

The fabric plies or steel cords (plus breakers) of a belt, as distinguished from the rubber covers. The carcass provides the tensile strength to move the loaded belt. More...

Carry cover

The material carrying side of a conveyor belt. In most cases thicker than the bottom cover.

Catenary idlers

A type of flexible belt-carrying idlers with ends supported in pivoted stands.

CBGuard
The most advanced conveyor belt monitoring system, based on radiographic technology. Supplies and processes nonstop live information about any deficiencies of a conveyor belt.

Center-to-center

The distance between the center of two pulleys. Sometimes also called "centers" or "center distance" or "conveyor length".

Ceramic pulley lagging

Used for high-capacity conveyors or in slippery environments. Offers higher wear resistance and a higher friction factor.

Chute lining

Highly abrasion resistant elastomeric lining in a chute to protect the metal chute from abrasion wear.

Clamping force

Depending on the friction factor of clamp and belt surfaces and on the (downhill) force. Chart.

Cleaner

A device for removing adherent material from the belt. More commonly used term: Scraper.

Cleat

Transverse raised sections on a conveyor belt to stabilize material carried up an incline.

Closed belt

See Pipe conveyor belt.

Closed-trough

A wrong term for pipe conveyor belt.

Coefficient C

The length coefficient used for calculating the secondary resistances. Chart.

Coefficient f

See f value.

Cold resistance

Usually, conveyor belts are resistant to up to -30°C. Lower temperatures may be achieved with special compounds. Constant movement of the belt may be required.

Concave curve

The concave radius of a conveyor must be sufficiently large to avoid belt lifting from the conveyor.

Compression set

The deformation in a material remaining after it has been subjected to and released from a compressive force.

Cord

Several strands of yarn twisted together

Cord fabric

A fabric with plied or cabled yarns in the warp direction and a light weight filling yarn spaced only sufficiently to process the fabric.

Cord stripper

A tool for easy separation of steel cords from the belt as part of the splicing procedure. Requires a winch. More...

Core rubber

Also called "insulation gum". The rubber used for filling the gaps in a steel cord and improving adhesion between the cord and the top and bottom covers.

Counter weight

The weight applied to the take-up assembly to maintain proper belt tension. Take-up length.

Cover

The outer rubber (or PVC) component of a belt. Protecting the belt carcass and providing drive friction. There are cover grades for a broad variety of applications. A cover usually consists of a principal polymer and assorted modifiers, carbon black, antioxidants, accelerators, fillers, plasticizers etc. Compounding.

Cover grade

Please follow this link for physical data of the most common cover grades.

CR

Polychloroprene rubber. Primarily used for covers for underground coal mining. Comparison. Safety.

Cracking

A sharp break or fissure in the surface.

Creep

The action of a belt alternately losing speed on the driving pulley and gaining speed on the driven pulley.

Crimp

The waviness of the yarn in a woven fabric or the difference in distance between two points on a yarn as it lies in a fabric, and the same two points when the yarn has been removed and straightened. Expressed as a percentage of the distance between the two points as the yarn lies in the fabric.

Crowned pulley

A pulley with a greater diameter at the center than at the edges.

Cupping

A belt tending to form a cup by raising the edges. Depending on severity, it may not be able to be guided by the idlers or even be loaded properly.

Cut edge

The uncovered edge of a belt, created by cutting after vulcanization. The carcass is visible from the sides.

Deep trough

A term used for a troughing angle of 45, rather 60°.

Degradation

A deleterious change in the chemical structure of a material.

Delamination

The separation of layers of material, for instance textile ply from top cover.

Denier

A yarn sizing system for continuous filament synthetic fibers on the basis of the weight in grams of 9000 meters of the yarn.

Density

The ratio of the mass of a body to its volume or the mass per unit volume of the substance. For ordinary practical purposes, density and specific gravity may be regarded as equivalent.

DIN

For Deutsches Institut für Normung, German Institute for Standardization. World's first standards for conveyor belts were published by DIN in Germany.

Dipped fabric

A fabric coated with rubber compound by passing through a rubber solution and drying.

Drop energy

The energy caused by the drop of the conveyed material onto the conveyor belt. Depending on lump size, drop height etc. See also Impact resistance.

Dynamic splice strength

The test and evaluation method is described here. Usual dynamic splice strengths are given in table 10 of DIN 22101. More...

E' and E''
E' is the dynamic modulus of the rubber which is in phase with the applied strain loading. E'' is the loss modulus, which is out of phase with the applied strain. The ratio of E''/E' = tan delta, which is the internal friction of the rubber. E' is an important factor for low indentation rubber.

Elasticity

Tendency to return to the original shape after deformation.

Elastomer

A viscoelastic, amorphous  polymer with low Young's modulus and high failure strain. Sometimes called rubber. Properties. Production.

Electrical conductivity

A measure of how well a material accommodates the transport of electric charge, measured in Ohm (Ω). Photo.

Elevator belt

Used for vertical conveying, with buckets mounted to it.

Elongation

The total belt elongation consists of an elastic (which recovers) and a plastic (which remains) portion. As per ISO 9856 a belt sample is subjected to a sinusoidal cyclic stress that varies from 2 to 10 % of the belt's nominal breaking strength. Test

Elongation at break

The percentage the rubber or belt can be stretched until it breaks.

Endless length

The length of a closed belt (without splice allowances).

Extrusion

A process whereby rubber is forced through a shaping orifice. More...

Eytelwein's equation

Determines the optimum difference between the forces F1 and F2 without belt slip. Equation.

Fabric belts

See textile conveyor belts.

Fastener

See "mechanical fastener".

Fatigue

The weakening of a material occurring when repeated application of stress causes permanent strain.

Feeder belt

A belt that discharges material onto another conveyor belt. Often used for belts extracting bulk materials from under a dump hopper or regulating feed to a crusher or screen.

Filament

A continuous fiber of discretionary length.

Fire or flame resistance

Retards the burning action of fire or flame. Achieved by adding fire retardants to the compound or by using fire resistant elastomers or plastomers. More...

Flat-to-trough transition zones

The transition length between pulley and deepest trough station. This length must be sufficiently high to prevent major additional tensions in the conveyor belt edges. Influencing the required conveyor belt breaking strength.

Fleximat belts

A trademark for "woven" steel cord conveyor belts. Belt manufacturers tend to use "Flex" in their own belt names. More.

Friction

The resistance to tangential motion between two surfaces. For rubber, the classical laws of friction are not applicable, since rubber has no rigid surface. The individual friction factor must be determined experimentally. In general, higher hardness and abrasion resistance result in lower friction. Chart.

f value

The coefficient f (also called artificial or fictive friction or resistance coefficient) is resulting from the correlation between the weights and the motional resistances of the belt conveyor. A typical f value would be 0,016.

In optimum installations with low rolling resistance belts, even f values of around 0.010 have been found. Chart.

In contrary to DIN and ISO, CEMA works with Kx, Ky and 0.015 instead of f, which f is a sum effect of.

Gouging

The effect of sharp heavy material falling onto a conveyor belt cover to loosen or tear out pieces of the cover. Photo

Gradient

There is a wide choice of conveyor belts for all gradients. From normal troughed conveyor belts, via pipe conveyor belts through to vertical elevator belts. Table.

Gravity take-up

A mechanical system that adjusts for the stretch or shrinking of a conveyor belt automatically by a weighted pulley in the system.

Grizzly bars

The bars at the loading point  absorb the impact energy from the lumps and redirect the (big) lumps to the belt; fines fall on the belt before the lumps.

Grooved lagging

Lagging with round or angular grooves to minimize material buildup on the pulley.

Hardness

Degree of resistance to indentation. Determined in ° Shore A. More...  Photo.

Head pulley

The pulley at the discharge end of the conveyor.

Heat resistance

Normal belts usually are resistant up to 80°C. Special compounds can increase the temperature resistance to around 200°C.

Hooke's Law

Hooke's law of elasticity states that if a force (F) is applied to an elastic spring, its extension is linearly proportional to its tensile stress σ and modulus of elasticity (E): ΔL = 1/E × F × L/A = 1/E × L × σ

Horizontal curve

The radius of a horizontal curve is required for the layout of the diameter of a pipe conveyor belt. More...

Hose belt

See Pipe conveyor belt.

Hysteresis loss

A loss of mechanical energy due to successive deformation and relaxation, measured by the area between the deformation and relaxation stress-strain curves. See also "Elongation".

Idler

A non-powered roller supporting the belt.

IIoT

Industrial Internet of Things. Electronic interaction between different components of a belt conveyor. The belt can be integrated digitally by the output of X-ray monitoring systems.

Impact

A stroke of a body dropping on the belt.

Impact idler

A belt idler having a resilient roll covering, resilient molded elastomer rings, springs or other means of absorbing impact energy at the place where material falls onto the belt.

Impact resistance

The relative ability of a conveyor belt assembly to absorb impact loading without damage to the belt. See also "transverse reinforcement". Test.

Inclination

The gradient of a conveyor. The maximum (uphill) inclination for non-profiled belts is around 18° for ore. In general, the angle of repose of the conveyed material must be larger than the inclination angle of the conveyor. Chart.

Inspection

Since the conveyor belt is permanently subjected to many strains and stresses, frequent, regular inspection of it is important. More...

Indentation rolling resistance

The energy consumed by internal friction caused by deformation when the belt moves over idlers. More...

Joint

The connection of two belt ends. More common term: splice. More...

Kevlar

A trademark for para-aramide (aromatic polyamide). See Aramid.

Kinking

A temporary or permanent distortion of belting caused by doubling the belt on itself.

Lagging

A smooth or embossed covering on a pulley to increase friction between belt and pulley.

Leno weave

An open mesh fabric in which the warp yarns are held by the filling yarns, with the filling yarns twisted around alternating warp yarns in opposite direction. Sometimes used as impact breaker.

Load support

Defining the belt's sag on the idler gaps. The sag may be an issue for very thin belts and wide gaps. Term widely used in North America.

LRR

Low rolling resistance. More...

Lump size

Conveyor belts are highly strained at the material feeding points. The intensity of the impact energy depends on the lumps' size, weight and shape.

Maintenance

Proper maintenance is very important to get the most out of your belt. Longer belts should be monitored by state-of-the-art systems based on X-ray technology. More...

Maximum tension

The highest tension occurring in any portion of the belt under operating conditions.

Mechanical fastener

Any mechanical device used to join the ends of belting. Sometimes also used for temporary emergency repairs. Illustration.

Modulus of elasticity

The force divided by the percent elongation to cause the elongation, related to the belt width. The lower the stretch, the higher the MoE. The MoE, sometimes called belt modulus, is influenced by the textiles (for instance the crimp of the yarn) or steel cords used and the way of belt manufacture, for instance the tension during vulcanisation. Example: The MoE for a 800/St2500 belt is 200 kN/mm. To stretch 1 m of this belt (elongation 0,15 %) by 1,5 mm, a tension of 240 kN is required. This is approximately 12 % of the nominal belt breaking strength.
The belt manufacturer should be consulted for exact figures. Equation.

Monitoring

Essential part of a Preventive Maintenance programme and IIoT. Extends belt life, reduces costs, increases safety. More...

Motion resistance

The resistances - "main, additional, inclination, special" - when moving a belt on a conveyor system. Illustration.

Moulded edge

A solid rubber belt edge formed in a mould or against edge irons. Another option are cut edges. The technical differences are small. Steel cord conveyor belts always have moulded edges.

Mullins effect

A particular aspect of the mechanical response in filled rubbers in which the stress-strain curve depends on the maximum load encountered. The phenomenon can be idealized as an instantaneous and irreversible softening of the stress-strain curve that occurs whenever the load increases beyond its prior all-time maximum value. At times, when the load is less than a prior maximum, nonlinear elastic behavior prevails.

Nip

The clearance between two rolls of a calender.

Nylon

See "polyamide".

Paper marks

Impressions of release paper, which is being used for preventing the unvulcanized belt stick to the press platens during the vulcanization process. The impressions look like small cracks on the cover surface. Usually they are abraded after a short time and do not affect the belt's life expectancy or performance.

Payne effect

Is observed under cyclic loading conditions with small strain amplitudes, and is manifest as a dependence of the viscoelastic storage modulus on the amplitude of the applied strain.

Permanent elongation

Plastic elongation. See "Elongation".

Permeability

Usually the quality or condition of allowing passage of air through a steel cord to identify the degree of rubber penetration.

Pipe conveyor belt
A closed conveyor belt for tight curves and for protection of the environment. More...

Pitch

Also called "spacing". The distance between the middle of adjacent steel cords in a conveyor belt.

piw (pounds per inch of width)

A term used in the USA, indicating a belt's "working tension". See also here.

Plastisol

A suspension of a finely divided polymer (PVC) in a plasticizer.

Ply

A layer of fabric in a belt.

Polyamide

High-elongation fiber, normally used for the belt's weft for good troughability. As warp recommended only for specific applications because of its poor plastic elongation behavior. Absorbs moisture of up to 10 % of its own weight.

Polyester

Low-elongation fiber, normally used as belt warp. Almost no moisture absorption, good dimensional stability.

Polymerization

The process that converts monomers into polymers.

Press length

The length of a belt that can be cured at one time.

Pressure under steel cords on pulley

As a rule of thumb, the pressure between steel cord and pulley should not be higher than 2 N/mm².

Preventive maintenance

Avoiding premature failures through condition monitoring. More...

Prescriptive maintenance

A higher level than Preventive Maintenance. Additionally informs what actions to take. Most advanced radiographic monitoring systems are able to provide this for steel-cord conveyor belts.

Pulley diameter

There are requirements on the minimum pulley diameter. A bigger diameter can have a positive effect on belt life.

PVC impregnated

A textile carcass impregnated with PVC compound (plastisol). Illustration.

Rating

The minimum belt breaking strength (DIN) of a belt in Newtons per millimeter of belt width (or in kN/m).

In the USA sometimes used as a term for the working tension.

Recycling

Most conveyor belts are not pollutive because of their organic components.

Regenerative conveyor

A conveyor for which the head is at a substantially lower altitude than the tail (downhill conveying), generating power.

Repair

There are many repair methods for all kinds of belt damage. It is recommended to contact the belt manufacturer for optimum instructions. The most reliable method is a hot repair. Belt damage that reaches down to the belt carcass should find immediate attention, in order to prevent even more serious consequences. See also Preventive Maintenance.

Return idler

Part of a conveyor's return/bottom/lower run.

Return side

The non-carrying belt side towards the pulleys. Usually thinner than the carry side.

Rheometer

A device to measure the shear stress of rubber under the influence of temperature and pressure under a twisting cone. More...

Rip detection

A system detecting a lengthwise damage of the conveyor belt. Most common are sensor loops embedded in the belt's cover at a certain spacing. See here. Also other external - X-ray, mechanical, radiant or optical - systems can be used.

Rip protection

A system to prevent the intrusion of foreign bodies into the belt and its subsequent slitting. This may be done by a simple breaker (a fabric ply) or single synthetic transverse cords. More...

RMA

For Rubber Manufacturers Association. Since 2011, all rights are with ARPM. More...

Rock box

Absorbs the impact from big lumps by filling the rock box first, so other lumps bounce off of the pile onto the belt. It reduces the free fall of the material to the belt.

Rolling resistance

Also called indentation rolling resistance. The resistance by deformation that occurs when the conveyor belt moves over an idler. The energy of deformation is greater than the energy of recovery. The hysteresis energy loss is depending on the viscoelastic properties of the belt. More...

Rotary press

Also called Rotocure or Auma. A vulcanizing machine consisting of a rotating, heated drum with a flexible steel band partially encircling the drum, which continuously advances the belt while under pressure and heat between drum and band. Illustration.

Rotocure

See Rotary press.

Viscoelasticity

The property of materials that exhibit both viscous and elastic characteristics when being deformed. Viscoelasticity is the result of the diffusion of atoms or molecules inside an amorphous material.

Viscosity

The resistance of a material to flow under stress. The higher the viscosity, the thicker the material. Illustration.

Vulcanization

An irreversible process during which a rubber compound, through a change in its chemical structure, becomes elastic. More...

Vulcanizer

A mobile curing machine for field splicing (also called press). More...

Warp

The lengthwise yarns in a woven fabric.

Wear resistance

A combination of abrasion and cut resistance. The severity of the wear depends on the nature, size, weight, shape and trip rate of the conveyed material. New test methods are being discussed.

Weave

A fabric pattern description denoting a specific relationship of warp and filling yarns at specific locations in the fabric.

Weft

The crosswise yarns in a woven fabric.

Width
The belt width is usually given in mm (DIN/ISO: 400, 500, 650, 800, 1000, 1200, 1400, 1600, 1800, 2000, 2200, 2400, 2600, 2800, 3000, 3200. AS/BS: 300, 400, 450, 500, 600, 650, 750, 800, 900, 1000, 1050, 1200, 1350, 1400, 1500 1600, 1800, 2000, 2400, 2600, 2800, 3000, 3200).

Wire

The smallest part of a steel cord. More...

Working tension

Used in the USA to determine the belt rating (piw). It is up to the belt manufacturer to decide on the actual belt breaking strength. More...

Wrinkle

An appearance usually resulting from curing with separation paper or cloth.

X-ray monitoring

Most advanced method to scrutinize the entire conveyor belt's condition. More...

Young's modulus

The stress per unit strain for elastic materials. Equation.