Introduction
The type of media you choose for your aggregate screen is critical to your plant’s performance.
There are many different factors to consider when selecting the material for your screen. Depending on what type of screen you choose, you will have to find the right balance between open area (or throughput) and screen life to determine the highest economic value for your application.
Factors to consider
The percentage of open area in a screen is very important to consider.
A large amount of open space gives the particles a greater chance to fall through the holes in the screen media. This results in a more accurate separation.
However, when there is more open space on the screen, the screen may lose durability or life expectancy. Therefore, the screen may not last as long and may need to be replaced more frequently.
A smaller amount of open space means less holes for the material to fall through. To compensate for less holes in the screen, the total screen area will need to be increased.
Types of aggregate screen media
McLanahan offers three different types of screen media. Each has its own specific applications and benefits.
Woven wire screen cloth
Woven wire screen cloth is the most widely used and accepted media for screening systems. These types of screens have a greater number of holes.
However, with this type of screen media, you trade wear life for open space. Woven wire screens have a much shorter wear life than other types of screens.
Fortunately, these metal screens are the cheapest type of screen and the easiest to replace, which make them the preferred screen of choice for most applications.
Pros
✔️ Most widely used and accepted
✔️ Greater number of holes in the screen
✔️ Least expensive
✔️ Easiest to replace
Cons
❌ Shorter wear life
Rubber screen panels
Rubber panels are most often used for dry applications or abrasive materials. This type of screen should be used for heavier, coarser material that would otherwise damage a standard wire screen.
With this type of media, there is a large trade-off between the throughput and screen life. Although they have less openings than wire screens, rubber panels will last longer because they are heavier and can withstand larger, more abrasive material.
Operators should also be cautious of the weight of the material going through the screens. If too much weight is put onto the screen, the stroke will be decreased, causing the stratification to decrease. Essentially, this will lead to a loss of efficiency and will hurt production.
Also be aware of how much weight is put onto the screen, as going over the screen’s capacity can cause cracking in the rubber media.
Although this option costs more up front than a standard screen, it can have long-term benefits that wire screens do not.
Pros
✔️ Can withstand heavier, coarser material than a woven wire screen
✔️ Long-lasting
Cons
❌ Have less openings than woven wire screens
❌ Cost more than woven wire screens
Polyurethane screen media
For wet applications or abrasive materials, a polyurethane screen would be the best option.
Like rubber panels, there is a large trade-off between open space and wear life when using polyurethane screens. Polyurethane screens have much less area than wire screens, but they are much more durable.
Polyurethane screens should only be used if the economic advantages of the longer screen life are greater than the lost output of tons per hour.
Be cautious of how much weight is put onto these screens, as the amount of material being fed onto the screen should not exceed the screen capacity.
If too much weight is put onto the screen, the stroke and stratification of the screen will be affected, resulting in a decrease in efficiency and/or damage to the screen.
If plugging tends to be a problem in your screen, switching to a polyurethane screen may be very beneficial. Because of the screen’s flexibility, particles are less likely to get clogged in the screen’s holes.
Pros
✔️ Can handle wet and abrasive materials
✔️ More durable than woven wire screens
✔️ Screen flexibility reduces plugging
✔️ Longer screen life
Cons
❌ Less open area reduces throughput
Selecting the right screen media for your application
When selecting the media to use in your screen, it is important to consider the size and type of material that will pass through the screen.
Choose woven wire screens for most applications unless particles would otherwise damage the screen.
For dry, coarse materials, consider switching to rubber screen panels if a wire screen is unable to withstand the ruggedness of the material.
If plugging is a problem in your wire screen, it may be beneficial to switch to a polyurethane screen to eliminate this issue.
For questions regarding screening, please contact McLanahan for assistance.
