and Rubber Screening Glossary of Terms
Select the first letter of the word from the list above to jump
to appropriate section of the glossary.
Wear due to friction.
The clear opening size, as in length, width or diameter of the opening. Apertures may
also involve special shapes such as rectangular (oblong) or triangular configurations.
The device (tooling) utilized in the molding process that determines the shape and size
of the aperture. One aperture pad usually provides a multiple of individual apertures.
Filling in and clogging of the screen apertures. This problem when encountered, may be
corrected by increasing the "taper" or "draft angle" of the apertures.
When replacing wire cloth with Polyurethane, describe in detail the nature of any
blinding problems. With the correct taper angle (draft) blinding problems can usually be
The material between the apertures at right angles to deck flow, also referred to as
the cutting edge.
- bridge depth
This term defines the thickness (in depth) of the bridge between the apertures.
- buffer strips
See "crown bar cover".
The arc of the screen support surface to facilitate screen tensioning, determined by
the various heights of the crown bar rails (stringers) provided on the screening deck.
- crown bar cover
A protective layer of rubber or polyurethane, contoured to fit over the crown bar rails
of a vibrating screen deck to prevent wear of the rails and screen while allowing uniform
tensioning of the screen. Also referred to as "buffer strips" and "channel
rubber" or "channel polyurethane".
A device installed at right angles to the flow of material to enhance screening by
slowing the travel of media across the screening surface.
The separation of liquids and solids. Solids travel over the screen while liquids pass
through screen apertures.
Tapered relief provided on the vertical element of bridge and rib components. The draft
angle utilized in most applications is two degrees per side.
Blinding problems encountered utilizing woven wire screens should be significantly
reduced or eliminated with the use of polyurethane.
This term is used to express hardness, typically preceded with the value and shore
scale, i.e. "85 Shore A Durometer".
Elastic substance occurring naturally, as natural rubber, or produced synthetically, as
- fast taper
Draft angle, typically four degrees per side utilized to prevent blinding.
Material traveling across the screen surface.
- flow divider
A device installed on the screens top surface running parallel with flow to prevent
material from traveling down the screens length over areas which have no aperture
Flow dividers are not required with Flowmax Modular Systems.
- flow restrictor
- formed edge
Edge preparation provided on the sides of a screen panel parallel to flow, to
facilitate clamping and tensioning.
- impact panel
A solid panel (screen Module) without apertures, used in areas subject to severe
impact, typically located directly under the feed chute.
- injection molding
A method frequently utilized in the manufacture of polyurethane screen segments. While
this method is extremely cost effective when producing sizable quantities of a given
aperture specification, the properties of the injection molded polymers (thermoplastics)
do not offer the superior characteristics of "open cast" (thermoset)
- long slots
Rectangular (slotted) openings (apertures) with the length aligned parallel to the
length of the screen deck in direction of material flow. Also referred to as "slots
long" and "slots wf".
Long slots are used to increase throughput (open area) when particle sizing is less
- maximum overs
The maximum size material that will contact the screens surface.
A replaceable screen segment (element), typically provided in square 12" x
12" or rectangular 12" x 24" sections.
- module thickness
Modules may be provided in various thickness' which govern the overall strength and
impact resistance. Industry standards include 30mm, 40mm, 50mm and 60mm.
- open area
The ratio of useable openings (apertures), to the total area of a module expressed as a
percentage. Many systems require clamping devices which cover the edges and/or a portion
of the apertures on each module. With reference to these systems the published open area
is often misleading, as the loss of open area utilized for fastening is not taken into
Flowmax systems do not require external clamping methods such as locking pins or
clamps. Published open areas reflect the actual effective screening area.
- open cast
The method of manufacture utilized to obtain maximum wear characteristics in
Material that is "over" (larger than) the screen aperture (opening) size
which travels across the screens surface without passing through.
Also referred to as "oversize material".
- percent open
Percentage of useable open area.
Near size particles trapped in screen apertures (openings) preventing passage of under
size particles. This problem commonly occurs when using wire or perforated plate screens.
Polyurethane screens are less susceptible to plugging due to the advantage of having
tapered relief openings.
- Retarder bar
Similar to a dam in purpose, yet smaller. Used to restrict the flow of material,
balance distribution and break friable lumps. Also referred to as "flow
The area between each aperture on a module, running parallel with deck flow.
As rib width is increased, strength will increase while open area will decrease
- rib depth
This term defines the thickness (in depth) of the ribs between apertures.
- shore hardness
The scale by which a polyurethane screen module or component is measured for hardness,
typically expressed as "shore A".
As the hardness is increased, abrasion resistance tends to increase while impact
resistance decreases proportionately.
As the hardness is decreased, abrasion resistance tends to decrease while impact
resistance increases proportionately.
- short slots
Rectangular (slotted) opening (aperture) with the length of the slot aligned at a right
angle to the direction of material flow. Also referred to as "slots s" and
Short slots are used to increase throughput (open area) when particle size is critical.
- skid bar
Running parallel to flow, a wear surface raised above the screen to prevent maximum
oversized material from coming into contact with the screen surface.
- slow taper
In ideal conditions where no blinding problems have been experienced, a slow taper (two
degrees included angle) may be utilized to increase open area.
- split aperture
Aperture "rib" section is split, allowing considerable flexure as an aid to
prevent screen blinding.
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