Looking for a school level physics answer....

Wolfetone

Sorry to be a pain, but I'm not a qualified engineer. I need some traction force questions worked out. I have two conveyor belts made by different manufacturers but to almost identical specifications. They describe the traction capacity of their respective belts differently which is confusing me as I work out that the belts should have fairly similar spec but haven't. Can someone tell me where I'm going wrong?

Both belts are 3mm thick 95shA polyurethane with no traction fabrics, just monolithic PU. I believe that 1kg = 9.8newtons.

Conveyor belt number one is described as having a traction capacity of 1.8kg/cm at 1% tension which I work out as;

= 1.8kg/cm 
= 17.4N/cm
= 1.76N/mm
÷ 3 (3mm thick belt)
= 0.586N/mm2
= 5.86daN/cm2

Conveyor belt number two is described as having a 10daN/cm2 which I work out as;

= 10daN/cm2
= 100N/cm2
= 1N/mm2

Why would these not match or is one company over egging their figures?

Can someone put me out of my misery?

For those mildly curious, this is a monolithic conveyor belt;


 

Elwood

My guess would be that number 2 are giving their figures for a difference tension. Can they provide you with that?

What I do know is Kg (mass ) is not directly compatible to Newtons (force). I think there is a difference measure or unit for force Kg.

Wolfetone

Thanks for that. Kg force is mentioned on their data sheet seemingly as an alternative to newtons. There is a conversion of 9.8 newtons to the kg force. 

mart

Can’t you just put a jumbo jet on both and see which takes off first?

Wolfetone

mart said:

Can’t you just put a jumbo jet on both and see which takes off first?

Oh no, I remember that thread 

TimmyO

"÷ 3 (3mm thick belt)"

why are you doing this step?

LewisYL7

https://www.convertunits.com/from/DAN/CM%5E2/to/kilogram/square+centimetre

Looks like kg/cm2 is almost 1:1 with daN/cm2. One step I think you did do wrong is there are 100mm2 to a cm2 not 10 but as you converted back to cm2 it doesn’t matter. Not sure if I’ve really helped there!

Wolfetone

TimmyO said:

"÷ 3 (3mm thick belt)"

why are you doing this step?

Because the measure is 'per cm' which is linear and by dividing by three reduces the figure to a square millimetre. 

Sporky

I'm an electronic engineer not a mechanical one, but isn't the cm in that more likely to be the width of the belt  not the thickness?

I can see how the capacity of the belt would vary with width, but the thickness of that belt is set at 3mm, no?

[edit] or should it be cm^2, for the surface area of the belt? 

JohnnyPlectrum

Sporky said:

I'm an electronic engineer not a mechanical one, but isn't the cm in that more likely to be the width of the belt  not the thickness?

I can see how the capacity of the belt would vary with width, but the thickness of that belt is set at 3mm, no?

[edit] or should it be cm^2, for the surface area of the belt? 

I'd assume a traction capacity is not dissimilar to a friction coefficient rather than the belt's tension capacity.
First belt's value is per cm whereas second is per square cm. You need the belt width of the first to be able to compare the two.
You'd expect the value to be a pressure ie a load per unit area rather than a udl. 
Looking at the figures though, the second belt has a vastly superior traction force.
The belt looks about 30cm wide so belt 1 would be 0.6N/cm2 compared to 100N/cm2 for belt 2 and that can't possibly be right?

hywelg

It is entirely possible that different companies take different opinions about tolerances and safety factors. It does appear that one company is rating it's belting more highly than another. What you don't know is whether both companies use the same reinforcement within the belt. 

Is the lower figure within design capacity? Do both have matching frictional properties? Are they equal cost/CoO ? What is that cheese ?:)

west

the answer is Cheeeeese mmmmmm ....