school board.png

TG Basics

Confidential - For internal use only

Thoses informations are only a small simplified part of existing knowledge around conveyor belt

Contact me for more

Arnaud WARTELLE

Materials : Elastomeres and plastics

Abrasion loss

DIN53516/10N

- Lower is better

- Check 10N or 5N

- Alternative = ISO 4649  

Image1.jpg

Examples        20                35             50               90             130         mm³

PUR              Exellent        Average        Poor 

Rubber                                              Exellent        Average        Poor 

Belt grade                                                                                  A        M       N

Hardness Shore A

Extend to Shore D

For elastomer only

 

- Higher or lower is not better, just different

Image3.png
Image1222.png

Elastomere temperature

Apart from being a danger of degration is too high, temperature also infue on the elasticty of eslatomere.

Higher = softer  /  Lower = harder

Therefore, sometimes it's necessary to adjust the use of elastomere or to use a different hardness

Natural Rubber

Positive

Good Price

Good Friction

Good abrasion resistance (100mm³)

High impact and vibration absorption

Good elasticity

35° to 90° Shore A

150 to 90 mm³ ISO4649

 

Negative

Oil degradation

80°C max

Costly molding tools

Best uses

Shock absorber

Drum coating

Sealing skirt

Centering system

Poor uses

Belt cleaner blades

Image6.jpg
Image21.png
Image8.jpg
Image10.png
Image11.jpg
Image9.jpg

​Rubber oil absorption

​Natural rubber can absorb oil, grease and hydrocarbon.
It inflates, becomes sticky, slack and lose its grip with vulcanized other parts.

Synthetic rubber can offeer more or less oil resistance : Nitrile, butyle, Neoprene...

Polyurethane is insensitive

Image1kkj.png

Synthetic Rubbers

Similar to Natural Rubber but…

Positive

Slightly higher temperature limit

Better chemical resistance

 

Negative

Higher price

Examples: Nitrile, Butyl, Neoprene ...

Image14.jpg

Rubber ozonolysis

On sea level, ozone (O3)  is mainly found in industrialized and high density zones. It can react with some parts in rubbers (Natural, Nitrile, Butyle) creating acids on surface and creates cracks. Thoses cracks can be infiltraded by dust material and interfers with belt cleaners

Polyurethane MDI Ester

Positive

High abrasion resistance (25mm³ to 12mm³)

Average impact absorption

Cheap molding tools

55° to 95° Shore A

30 to 20 mm³ ISO4649

Negative

Medium friction

High Price

80°C max

Bad vibration absorption

Bad elasticity

Hydrolysis weakness

Best uses

Scraper blade

Sealing skirt

Poor uses

Shock absorber

Motor pulley lagging

molecule PUR r12.png
Image16.jpg
SealBloc r2.png

Polyurethane hydrolysis

Hydrolysis is a chemical reaction where a polymere molecula is broken by water molecula.

For polyurethane, hydrolisys reaction start at 60°C.

First step the PUR becomes sticky plasticine.

Final result is a friable hard PUR.

Ikkljjkllkjjkmage1.png
Image1.png

Polyurethane MDI Ether

Out of

range

Similar to Polyurethane Esther but…

Positive

Slightly higher temperature limit

Better elasticity

Better hydrolysis resistance

 

Negative

Higher price and minimum quantity

Slightly lower abrasion resitance

Methylene-diphenyl-diisocyanate-3D-vdW.p

Other polyurethane

Out of

range

NDI: Rollers (Vulkollan®), silentbloc...

TDI : Foam, adhesives...

HDI, IPDI : paint, coating...

tdi.jpg

Rubber or polyurethane additives

Electrical conductivity
Increased abrsion resistance
Bactericidal

...

barium-sulphate-500x500.jpg

Polyethylene UHMW 1000 - 6000 - 7000

(Hostalen, Lactène, Lupolen, Stamylan, Supralen, Eltex)

Positive

Average price

Low friction

Average abrasion resistance

Food grade

Average impact resistance

Can be partially recycled

 

Negative

Poor abrasion resistance

Bad UV resistance (virgin/white)

60°C max

Bad elasticity

Image19.jpg
Image20.jpg

Best uses

Hopper coating

Impact bar top

Scraper deflector

Security bar

 

 

Poor uses

Scraper blade

Image21.png
Image22.png
Image24.jpg
Image23.png

Polyethylene HD

250 - 500

Similar to UHMW but lower price and quality

Polyamid 66

(Nylon, Ertalon, Tecamid, Tecast,  Sustamid, Traidamid, Nylatron)

Out of

range

Similar to Polyethylene but…

Positive

Higher temperatutre resistance 100°C

Slightly higher mechanical resistance

Cheaper price

Negative

Lower abrasion resistance

Lower chemical resistance

Hydrolysis weakness

Ozonolysis weakness

Image25.jpg
Image26.jpg

Rubber < PUR

Abrasion resistance

abrasion 120 201.png

Standart rubber quality offers ±120mm³ abrasion resistance

Very good  rubber can offer 50mm³ with expensive price

Standart polyurethane quality offers ±20mm³ abrasion resistance

Possible to reduce even more to 12mm³ with moderate extra cost

Oil resistance

huile.png

Natural rubber (and some sunthetic) can be damaged by oil, grease and hydrocarbons

PUR is perfectly resistant to oil, grease and hydrocarbons

Small quantity production

Tools and mould for rubber need to be string and expansive making difficult prototyping and small serie production

Polyurethane requires light and simple tools and mould easy to produce for prototyping and small serie production

PUR < Rubber

Hydrolysis resistance

heat-resistant-rubber-conveyor-belts-500

Standard MDI Ester PUR doesn't resist against hydrolysis and requires to be replaced by more expensive MDI Ether

Standard natural rubber has not sensitivity agaisnt hydrolysis with cheap cost

Mechanical

AlbertFrei2_KY_web.png
Image10.png

Polyurethane MDI Esther is not good for mechanical or impact applications

Rubber is perfect for mechanical or impact applications

Ex: silentblocs, primary screening mat

Friction

5f8858873d0288319fb149a2.jpg
ST PU r1.png
téléchargement.jpg
Image53.png

PUR offers less friction

For tracker this meeans less centering effect, water may cause even poor friction

Compensation low friction with more pressure is dangerous since PUR has less elasticity and can break easier

Rubber offers more friction

For tracker this means more centering effect

Materials : Metals and ceramics

Hardness Vickers (Hv)

Alternative : Hardness Rockwell (HRA), Mohs scale

For hard material only

 

- Higher is better against abrasion

- Gives a proportional indication of the wearing resistance

Be careful :

Harder   =   Weaker against impact

Image4.jpg

Sintered Alumina

Positive

Very high abrasion resistance

1100-1300 Hv

Food grade

400°C max

Low friction

Average compression resistance

Negative

High price

Poor impact resistance

Difficult to shape

Image27.png
Image28.jpg

Best uses

Drum lagging (profile wear issue)

Hopper coating

Low impact bar top

Rubber coating top

Security bar

 

Poor uses

Scraper blade (blunt issue)

Impact protection

Image32.jpg

Agglomerated Alumina Grains

Positive

High abrasion resistance

900-1100 Hv + epoxy

100°C max

High friction

 

Negative

High price

Poor impact resistance

Low compression resistance

Best uses

Drum lagging

Brake pad

Poor uses

Impact protection

Image34.png
Image35.jpg
Image36.png
Image37.png

Wear Resistant Steel (Mn, Ni, Cr, Ti)

(ex: Creusabro, Hardox...)

Out of

range

Positive

Good abrasion resistance

High impact resistance

450°C max

450-500 Hv

Negative

High price

Best uses

Chute

Conveyor Head Box

Poor uses

Belt cleaner blades

Image38.png
Image41.jpg
Image40.png

Cast Basalt

Out of

range

Positive

Good abrasion resistance

700-800 Hv

Average impact resistance

400°C max

Negative

Difficult to shape

Outdated material against sintered aluminate

Image42.jpg
Image43.jpg

Best uses

Chute

Pipe

Poor uses

Applications where sintered aluminate is possible

Image44.png

Wear resistant

Cemented Tungsten Carbide

(10%Co+Cr+V.C)

Positive

Ultra high abrasion resistance

1600-1800 Hv

700°C max

Low friction

 

Negative

Very high price

Very poor impact resistance

Low compression resistance

Image45.png
Image46.jpg

Best uses

Belt cleaner blades

Impact resistant

Cemented Tungsten Carbide

(20%Co)

Positive

High abrasion resistance

800-1000 Hv

700°C max

Low friction

Good impact resistance

Average compression resistance

Negative

Very high price

±30% lower lifetime

Best uses

Belt cleaner blades with impact

Mining bucket

Imagejjgghg1.png

Other special

Cemented Tungsten Carbide

- Food grade

- High chemical resistance

...

Sintered alumina blades < Tungsten carbide blades

Efficiency

May wear off with rounded edge

Always offers sharp cutting edge

Some uncommon acids can corrode it

Cleaning efficiency never drop

Tungsten carbide blades < PUR blades

Damaged belts

1445936426996.jpg

​Tungsten is hard and sharp and can shave chips from damaged belt surface

Polyurethane is soft and doesn't cut damaged belt

Less danger

Impacts / Mechanical lacing

Tungsten carbide can break under impacts becoming cutting and dangerous for the belt surface.

It can also becomes friable and so lasts a shorter time

(Impact resitant tungsten carbide exists but has shorter lifespan)

Image2 (6).png

As an elastomere, Polyurethane is unsentivive under impact

 No danger or lifespan reduction

Cleaning liquids

Tungsten carbide is hard and can't adapt to slight irregularities of the belt surface to stop liquids

Polyurethane is soft and offer a better seal-contact to stop liquids

Better drying effect

PUR blades < Tungsten carbide blades

Efficiency

Image1222 (2).png

Polyurethane is soft enough to let some fine dust pass in between blade and belt

​Tungsten is hard and offers a cutting edge able to stop smallest particles

Lifespan

Polyurethane wears out faster so it needs to be bigger and move a lot during its lifespan (bigger and more complex tension system)

lame Z² regular tungsten ususre.PNG

Tungsten carbide wears out much slowler so the blades can be smaller and doesn't need a lot of movement.

It also lasts longer and reduces interventions

Smaller blades and tension system are easier to install

Short movement needs less maintenance and simplier tension system

Less frequent replacement reduces maintenance and spare parts stock

Belt cleaners Basics

Positions

Image1 (3).png

Primary/ tangeant

Secondary / underlying

Internal

Technologie

technologie blk.png

Simple Multi-blade

Adjustable + Cushioned

Mono-blade

Cushioned Mono-blade

Adjustable Mono-blade

Adjustable Multi-blade

Autmatique adjustable Multi-blade

Automatic Adjustable

+Cushioned Mono-blade

Simple Mono-blade

Irregular wearing

Image67.png

Conveyor belts carry material in mound shape, leaving more material to clean in the center than the sides

Therefore, all belt cleaners will have more wear in the center

Manual compensation

Image4.png

To compensate the irregular wear, belt cleaner needs to be able to change its shape

Segmented /

adjustable mono-blade

Image100.png

Adjustable Multi-blade

Quickening wearing effect

If the belt cleaner maintenance is forgotten for a long period, it can start to let material pass trought it. In reality, material start to pass over the blade(s) and its wear speed increases a lot.

qw0.png

Very slow wear due to the belt

qw1.png

Slow wear due to some dust

qw2.png

Quick wear due to grains and dust

Automatic compensation

To prevent forgetting of maintenance (quick wear) and/or to reduce it, some belt cleaners have partial automatic compensation

Image72.jpg

Automatic Mono-blade

Image14.png

Automatic Multi-blade

Constant pressure

Image10.png
P-TZ r3 B.JPG
Image8.jpg

Wearing of the blade, irregularity on the belt thickness, belt cleaners needs to have a dynamic and adaptative pressure system to be adaptatives, ex: steel springs, elastomeres, air pressure...

Some of them can't works on 2 ways belts

It's also the solution to "stock" pressure and reduce interventions

Importance of tension pulley for pressure

Image78.jpg
Image2thytyh.png

The tension pulley, apart from keeping enought winding on the head drum (cf. EULER formula) also prevents the belt to move up and down where secondary belt cleaner is installed. Ex: belt way reversion, start of long conveyor without adaptative tension...

Waring: when moving down, the belt can have a huge force and movement distance above the cleaner elasticity therefore it can damage it.

Its cleanliness has to be monitored to avoid belt deformation or lift up.

It's also important to clean it before installing a belt cleaner (wrong belt shape)

Without compensation < With compensation

Efficiency

Image1012.png
Image15 (2).png
Image72.jpg
Image100.png

Belt cleaners without compensation quickly lose cleaning efficiency and requires high frequency blades replacement

Belt cleaners with compensation maintain cleaning efficiency and reduce blade replacement

Pollution

Image23 (2).png
cleanscrape.png
demo comp r3 2.png

With gap emergence, materials can be stuck inbetween the cleaner and the belt,   accumulate and push aside the cleaner and can make scratch on the belt 

With permanent contact, no danger of material stuck

Cleaning angle

Good cleaning

1. Right model

2. Good angle

3. Good pressure

Angle adujstement

90° angle

Optimum cleaning

95° angle

Strong vibrations

Bad cleaning

85° angle

Bad cleaning

Can be used when huge surface bumps and damages

Specific angle modification

Image64.png

Some belt cleaners uses elasticity that change the angle

Need to check angle when belt is running/ adjust a different angle when stopped

Tangent angle

Image65.png
Image66.png

On primary position, the force pushes against the belt cleaner

On 85° angle, there is a specific danger to damage (swallowing) the belt cleaner and so also the belt

1 or 2 ways belt

Mechanical ability

Imagenhgnh2.png

Material evacuation

Obtuse cleaning angle < 90° cleaning angle

Image62.png
Image61.png

Needs nearly perfect surface, can be dangerous if no secure pressure system (sometimes not enought like hole in belt) 

Can increase belt cracks or damage extra thickness splicing

Clean any kind of surface, new or old belt, nearly never any danger

Cleaning troubles

Sealing skirt wear

usurebavette1.png
usurebavette2.png

Material dust and sealing skirts can create lateral gaps on the belt very difficult to clean. Sometimes it's just impossible.

Scratch wear

belt scratches.png

When the belt has scracth wear, some dust can pass throught the cleaner without any solving solution. Scrathes can occur more in specific industry like recycling.

Material hardening

sw colmatée.png

​Some material harden when stuck on cleaner blade (ex: glass composition). This creates a different front shape that allows material to built up and push aside cleaner and belt, severly reducing cleaning efficiency. There is no other solution than clean regularly the cleaner but unfortunately this is nearly never made.

No blade security < Blade ejection security

In case of accident without ejection security, blade(s) and support can be definitely damaged and can damage the belt by being stick in abnormal shape and position

Image8 (2).jpg

In case of accident with ejection security, no damage to the belt or cleaner support

The blade can also sometimes be recovered and reinstalled

Secondary cleaner < Primary cleaner

Space

prim sec 3.png

Secondary cleaners are installed in reduced space (hopper edge, tension pulley, limited high...) sometimes not available

Primary cleaners are installed in more free space nearly always available

Scraped material

prim sec 4.png

Secondary cleaners could require to modify the hopper entrance and/or could have clogging issue

prim sec 1.png

Primary cleaners realse scrapped material directly into the flow

Primary cleaner < Secondary cleaner

Installation adjustement

Image66.png

Primary scraper can be difficult to adjust properly because the angle is a efficiency key point easy to miss (especially with tungsten carbide)

If the adjustement is not correct <90°, it can also leads accident of upturned cleaner (without security) and scratched belt 

Secondary scraper are quite easy to adjust

If the adjustement is not correct, there is nearly no risk of damage

Pressure

Primary cleaners are put in pressure directly on the head pulley

Therefore it's not possible to apply an important pressure

Secondary cleaners give pressure in a free space zone of the belt and can have higher pressure

Compatibility

pulley shape.png

Primary cleaner are not compatible with special shape pulley (SlideLag, squirrel cage pulley, etc...)

Secondary cleaner are compatible with any kind of pulley shape

Multi-blades < Mono-blade

Efficiency

Materials can pass inbetween multi-baldes

Mono-balde offers slightly better cleaning

Pollution

Multi-blades are not compatible with paper, wire or fabrics. Blades can stay stuck together with some material (ex: sugar)

Mono-blade is perfect for recycling and sticky material

Sensitivity

Multi-blades can suffer from holes or patches or can damage the belt even greater

Mono-blades has very reduced danger with holes and patches

Outgoing belt

Image1 (2).png

If the belt move too far on side, multi-blades can go out of the belt with possible damage 

- on the pulley lagging

- on the outside blade

- on the edge of the belt

The belt could also have difficilty to go back to center position

Mono-blades are not concerned by the movement of the belt

Blade(s) replacement

multilame reglage 2.png

On blades replacement, multi-blades require one by one adjustement

sw lame out.png

On blade replacement, no adjustement required

Mono-blades < Multi-blades

Unflat belt

Image73.png
Image10 (2).png

Mono-blades are not able to adapt their shape to not plane belt

This offers a uncomplete cleaning and quick wear zones

Image1.png
Image9.png

Multi-blades can adapt their shape to any kinf of belt

This cleaning is complete

Stuck particle

Image2 (2).png
Image12222.png
Image4.png

​If a particle comes in between the belt and the cleaner (punch in the belt), the complete mono-blade cleaner can be off from the belt​

The cleaning is no more efficient

​If a particle comes in between the belt and the cleaner (punch in the belt), only one blade of the multi-blade cleaner can be off from the belt​

The cleaning continues

Blade cost

Image15 (2).png
ext (23.jpg
multi change partiel1.png
multi change invert 1.png

When the center of the mono-blade cleaner is worn, the complete balde has to be changed

Image39 22.png

In case of accident, the complete blade has to be changed

When the center of the multi-blade is worn, you can change only the needed blades

You can also invert the center and sides blades at mid-life to delay the need of spare parts

Image8 (2).jpg

In case of accident, it's easy to change only the damaged blade

Complex flow < Direct flow

Image11.png
Image25.png

If the cleaned material has to encounter the cleaner structure due to complexity or size, it can easierly built up and completely clog the cleaner

Image26.png

Simplified shape and small size make short flow on the cleaner greatly reduce the danger of clogging

1 axis multi-blades < 2 axis multi-blades

Rotation

multi 1 axe.png
multi 2 axes.png

When multi-baldes move "back and forth"only , they can have difficulty to adapt to some irregular shape 

Multi-blades with "back and forth" + "pivoting" can offer greater adaptability

Complex assembly < Simple assembly

Parts and bolts

z2deboite.png
loihhh.jpg

Big quantity of parts increase the risk of mistake

Presence of bolts under the belt increase the risk of bloking since the cleaner is in the dirtiest place of the conveyor

Limited parts reduces the risk of mistake 

No bolts under the belt and nested blades prevent the risk of blocking

Ergonomy

Image35.png

Necessity to take time disassemble several parts to remove the cleaner

Big cleaner size makes it harder to install and to take out for maintenance

Big tension system use more parts and require more space

QL opened.png

Quick opening and remove of the cleaner

Small cleaner size makes it easier to install and to take out for maintenance

Compact or integrated tension system is simplier and require less space

Medium durability < High durability

Blade wear area

Image16.png

2x10 or 3x10

Tungsten carbide

Smaller wear area means smaller lifetime

Image17.png

3x15

Tungsten carbide

Bigger wear area means bigger lifetime

Protection

Unprotected structure has shorter lifetime

Painted.jpg

Painted structure

Protected structure has bigger lifetime

galvanized.jpg

Zinc platted structure

Robustness

55g

160g

245g

290g

335g

980g

RacloFlex N

Elastomer part is crucial and should be big enought to absorb vibration and keep correct elasticity for a long time

Belt centrers Basics

Side movements

- Convevor geometry

ex: heat source, weather & seasons, accident

- Component geometry

ex: worn pulley lagging, clogged pulley, blocked idlers, pulley or idlers alignement

- Belt geometry

ex: shape (banana), side storage, junction alignement failure

- External force

ex: perpendicular transfer, heterogenous loading, non centered loading, wind

Note : 2 ways belts are more capricious

Image2hyhy.jpg

Belt stop

Specific idlerrs can be used to try to stop the belt to a maximum outgoing position.

This solution is limited to low force.

On high force, the idler can be broken or cut, or the belt can fall back on itself.

Belt movement slow-down

​Inverted idlers bracket doesn't center the belt (except for specific "auto-stable" belt) It only slow down the belt movement but it makes the centrer efficiency less reactive and shorter

Oblic rolling effect

When a idler is oblic, its rolling movement create a pushing force on the belt perpendiculary to the rotation axle

Therefore, you can apply a force on the belt by adjusting idlers and pulley angles

oblique.png

3 idlers supports often present 2 oblic external idler to try to always push the belt to the center 

oblique3.png

Active centerers uses this principle with a central pivot to rotates and push the belt to the required direction

centerer principe.png

Detecting belt outgoing

​There are many different principle or mechanisms to detect belt position and  manage rotation on pivots

Thoses different systems have different advantage