Lateral Thinking?
A primary scraper blade is often softer than the belt cover.
If the blade is wider than the belt a gouge can eventually be developed in the blade edge due to continuous wear.
As the belt wanders from side to side the belt edges catch the edges of the gouge and there is a potential wear situation for the belt edges due to relatively high contact pressure.
If the blade is narrower there is more possibility for even wear accross the full blade face.
I am not personally aware of the complete validity of the premise: but that is how it was explained to me in 1978 and things do change. ■
Belt Cleaners
I am not sure of the correctness of the statement that "A primary scraper blade is often softer than the belt cover". I have found that cleaners are almost always higher in durometer.
It was explained to me as a cost issue. If the belt is properly trained and loaded, then the material never comes close to the edges of the belt. If there is no material on the edges why clean them? If you don't need to clean them, then you can save the cost of the blade material.
CEMA has established standards for the minimum width of the cleaner blade based on the belt width.
There are several other reasons, such as wear patterns, blade lubrication, heat build-up, etc. ■
Pre-Cleaner
Both former replies being perfectly valid, please have a look at attached sketch: a) The pre-cleaner blade is directed upstream against the direction of the moving belt b) by design it is pressed against the surface of the belt, which itself is rigidly supported by the pulley --> Conclusion: If the blade is wider than the belt, it will be only partly supported by the belt and thus a tippling effect around belt edge will occur, leading to immanent danger of cutting into the belt's edge.
R. ■
Re: Belt Cleaners
Dear all thank you very much for your replies.
I want now to go quite deeper on this topic. I am working on a project with a trough belt conveyor. The carrying material is hygroscopic sand with Mo and Pt, grain size 45-150m, density 1500kg/m3, flow rate is 120m3/h, belt speed is 1m/sec and the belt is flat EP type. I am a quite confused about what kind of cleaners I must use after discharging point on drive drum. Can I use a brush motorized cleaner or it is better toy use a scraper cleaner. If I select a scraper cleaner what material should be used for the blade? I can use a hard plastic (Acetal for example) or it is better to use a metal blade? Is there a possibility that the metal blade can cause damage to the belt? ■
Re: Belt Cleaners
Dear technic,
plain answer: Please contact your local + reputed belt cleaner supplier or connect to reputed manufacturers, contacts being readily available from the net. These points mentioned by you need to be analyzed in-depth by professional experience & supply competence, responsible decisions for an implemented solution should have a reasonable engineering background.
Best way, i fear, is not always the cheapest ... But then, it would imo have the best chance to be a working solution.
Conveyor performance stands or falls sometimes with the belt cleaners, perhaps you could have a look around in the different forums here for some of the points.
R. ■
Belt Cleaners
Dear Sirs,
I had read that precleaners blade must be always narrower than the belt width. Can you please explain me the reason for that? Which is the appropriate width for the secondary cleaner? It must be wider than the belt or no? Thank you in advance. ■