Shore 85 rating is quite high and can lead to drive pulley slip especially if the pulley lagging also becomes harder than normal. This is not guaranteed. It also depends on the demand power used with respect to the design threshold.

The drive pulley lagging and belt top and bottom covers are usually specified to be in the range of 55-65 when new. Age and use does cause the rubber to harden. The normal upper limit is around 75 Shore.

Tracking is another issue. Given that the belt rubber is changing in a dramatic manner, are there other factors at play? Is the belt undergoing unusual stress from its environment? How old is it? Is there heat involved? ■

Shore 85 rating is quite high and can lead to drive pulley slip especially if the pulley lagging also becomes harder than normal. This is not guaranteed. It also depends on the demand power used with respect to the design threshold.

The drive pulley lagging and belt top and bottom covers are usually specified to be in the range of 55-65 when new. Age and use does cause the rubber to harden. The normal upper limit is around 75 Shore.

Tracking is another issue. Given that the belt rubber is changing in a dramatic manner, are there other factors at play? Is the belt undergoing unusual stress from its environment? How old is it? Is there heat involved? ■

Shore 85 rating is quite high and can lead to drive pulley slip especially if the pulley lagging also becomes harder than normal. This is not guaranteed. It also depends on the demand power used with respect to the design threshold.

The drive pulley lagging and belt top and bottom covers are usually specified to be in the range of 55-65 when new. Age and use does cause the rubber to harden. The normal upper limit is around 75 Shore.

Tracking is another issue. Given that the belt rubber is changing in a dramatic manner, are there other factors at play? Is the belt undergoing unusual stress from its environment? How old is it? Is there heat involved? ■

Hi everyone,

or is this about the belt cover hardness???

May be the flexibility of the belt has something to do with its surface hardness..humm, it could obligate us to use bigger pulleys, lets say, in extreme cases.

Small and short conveyors carrying very abrasive materials.

Normally the belt companies show minimum diameters of the pulleys as a funcion of belt type and number of plies, not referring to its surface hardness.

Up to now I do not face such a problem.

Could you explain a bit more about this question?

Rgds

Alexandre Calijorne

caltrapc@yahoo.com.br ■

Hi everyone,

or is this about the belt cover hardness???

May be the flexibility of the belt has something to do with its surface hardness..humm, it could obligate us to use bigger pulleys, lets say, in extreme cases.

Small and short conveyors carrying very abrasive materials.

Normally the belt companies show minimum diameters of the pulleys as a funcion of belt type and number of plies, not referring to its surface hardness.

Up to now I do not face such a problem.

Could you explain a bit more about this question?

Rgds

Alexandre Calijorne

caltrapc@yahoo.com.br ■

Hi everyone,

or is this about the belt cover hardness???

May be the flexibility of the belt has something to do with its surface hardness..humm, it could obligate us to use bigger pulleys, lets say, in extreme cases.

Small and short conveyors carrying very abrasive materials.

Normally the belt companies show minimum diameters of the pulleys as a funcion of belt type and number of plies, not referring to its surface hardness.

Up to now I do not face such a problem.

Could you explain a bit more about this question?

Rgds

Alexandre Calijorne

caltrapc@yahoo.com.br ■

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Dear Sir,

We normally keep 65-70 shore scale-A as hardness. Now due to heat & agging it goes up. The figure 85 at new condition is high.

Regards.

A.Banerjee ■

Dear Sir,

We normally keep 65-70 shore scale-A as hardness. Now due to heat & agging it goes up. The figure 85 at new condition is high.

Regards.

A.Banerjee ■

Dear Sir,

We normally keep 65-70 shore scale-A as hardness. Now due to heat & agging it goes up. The figure 85 at new condition is high.

Regards.

A.Banerjee ■

There was a case circa 1980 where fire resistant belts were found to work harden to unacceptable limits. The exact hardness was not in the reports that I read at that time however the result was increased power consumption under load. This was determined to be caused by forcing the belt to assume the full trough of the idlers.

The problems was identified when a section of belt was damaged and a new section was spiced in. Motor Amps fell as the new section of belt passed through under load and raised again as the old section picked up the load.

Regardless of troughability which you may or may not suffer from, the hard rubber will have less grip on the idler rolls making it insensitive to idler adjustment and training. ■

There was a case circa 1980 where fire resistant belts were found to work harden to unacceptable limits. The exact hardness was not in the reports that I read at that time however the result was increased power consumption under load. This was determined to be caused by forcing the belt to assume the full trough of the idlers.

The problems was identified when a section of belt was damaged and a new section was spiced in. Motor Amps fell as the new section of belt passed through under load and raised again as the old section picked up the load.

Regardless of troughability which you may or may not suffer from, the hard rubber will have less grip on the idler rolls making it insensitive to idler adjustment and training. ■

There was a case circa 1980 where fire resistant belts were found to work harden to unacceptable limits. The exact hardness was not in the reports that I read at that time however the result was increased power consumption under load. This was determined to be caused by forcing the belt to assume the full trough of the idlers.

The problems was identified when a section of belt was damaged and a new section was spiced in. Motor Amps fell as the new section of belt passed through under load and raised again as the old section picked up the load.

Regardless of troughability which you may or may not suffer from, the hard rubber will have less grip on the idler rolls making it insensitive to idler adjustment and training. ■

85shore is a little hard for conveyor belt, generally the hardess is 65-75shore, for the steel cord conveyor belt the hardness is harder than than general fabric conveyor belt, as Alexandre Calijorne said "it could obligate us to use bigger pulleys" that is necessary for the hard conveyor belt.

Luke

swall.belting@gmail.com ■

85shore is a little hard for conveyor belt, generally the hardess is 65-75shore, for the steel cord conveyor belt the hardness is harder than than general fabric conveyor belt, as Alexandre Calijorne said "it could obligate us to use bigger pulleys" that is necessary for the hard conveyor belt.

Luke

swall.belting@gmail.com ■

85shore is a little hard for conveyor belt, generally the hardess is 65-75shore, for the steel cord conveyor belt the hardness is harder than than general fabric conveyor belt, as Alexandre Calijorne said "it could obligate us to use bigger pulleys" that is necessary for the hard conveyor belt.

Luke

swall.belting@gmail.com ■

Increase in hardness signifies a loss of plastisizer, which increase the elastic (dynamic) modulus and makes the rubber stiffer.

The belt will not trough (bend) as well and the local surface pressure will rise that raises the rubber's hysteresis and therefore consumes added power.

To maintain the limit on the rubber's strain level may also require an increase in the pulley diameter. This point is not obvious, since most pulley diameter criteria are more based on the pressure under the steel cord and axial and bending stress of the wires in the steel cord.

You probably will have less drive traction, which is a decrease in the driving friction so that belt slip may occur.

Belt splice strength may also suffer. This depends if the hardness also effects the core rubber surrounding the steel cords or fabric skim rubber.

The bond strength between cover rubbers, which are the normal measure of rubber hardness, may also lead to loss of adhesion between cover and core gum.

These properties vary with manufacturers. Some sell junk rubber and behave accordingly. ■

Increase in hardness signifies a loss of plastisizer, which increase the elastic (dynamic) modulus and makes the rubber stiffer.

The belt will not trough (bend) as well and the local surface pressure will rise that raises the rubber's hysteresis and therefore consumes added power.

To maintain the limit on the rubber's strain level may also require an increase in the pulley diameter. This point is not obvious, since most pulley diameter criteria are more based on the pressure under the steel cord and axial and bending stress of the wires in the steel cord.

You probably will have less drive traction, which is a decrease in the driving friction so that belt slip may occur.

Belt splice strength may also suffer. This depends if the hardness also effects the core rubber surrounding the steel cords or fabric skim rubber.

The bond strength between cover rubbers, which are the normal measure of rubber hardness, may also lead to loss of adhesion between cover and core gum.

These properties vary with manufacturers. Some sell junk rubber and behave accordingly. ■

Increase in hardness signifies a loss of plastisizer, which increase the elastic (dynamic) modulus and makes the rubber stiffer.

The belt will not trough (bend) as well and the local surface pressure will rise that raises the rubber's hysteresis and therefore consumes added power.

To maintain the limit on the rubber's strain level may also require an increase in the pulley diameter. This point is not obvious, since most pulley diameter criteria are more based on the pressure under the steel cord and axial and bending stress of the wires in the steel cord.

You probably will have less drive traction, which is a decrease in the driving friction so that belt slip may occur.

Belt splice strength may also suffer. This depends if the hardness also effects the core rubber surrounding the steel cords or fabric skim rubber.

The bond strength between cover rubbers, which are the normal measure of rubber hardness, may also lead to loss of adhesion between cover and core gum.

These properties vary with manufacturers. Some sell junk rubber and behave accordingly. ■

How do you measure the hardness of a running belt? Slip, under the circumstances so far described, will generate heat which will surely soften the rubber periodically. Have belt temperature cycles been recorded? Thermography even! A bit of rocket science. ■

How do you measure the hardness of a running belt? Slip, under the circumstances so far described, will generate heat which will surely soften the rubber periodically. Have belt temperature cycles been recorded? Thermography even! A bit of rocket science. ■

How do you measure the hardness of a running belt? Slip, under the circumstances so far described, will generate heat which will surely soften the rubber periodically. Have belt temperature cycles been recorded? Thermography even! A bit of rocket science. ■

We measured the hardness for the steel cord belt conveyor for a belt bucket elevator in a cement plant.

We measured in 30 defreent points and the average was 73.15 shore scale-A.But we found point with hardness 81 shore scale-A.

And also we noticed high wear on the drive drum rubber lining after short period from changing it.

Attachments

dscf4718 (JPG)

■

We measured the hardness for the steel cord belt conveyor for a belt bucket elevator in a cement plant.

We measured in 30 defreent points and the average was 73.15 shore scale-A.But we found point with hardness 81 shore scale-A.

And also we noticed high wear on the drive drum rubber lining after short period from changing it.

Attachments

dscf4718 (JPG)

■

We measured the hardness for the steel cord belt conveyor for a belt bucket elevator in a cement plant.

We measured in 30 defreent points and the average was 73.15 shore scale-A.But we found point with hardness 81 shore scale-A.

And also we noticed high wear on the drive drum rubber lining after short period from changing it.

Attachments

dscf4718 (JPG)

■