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Glossary of Sieving Terms

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acrylic spacer: Component of the Sonic Sifter stack assembly. 6 for full Stack. This ⅝" high clear acrylic ring are used as extenders when either the test material needs more space to move or to complete the Stack when there are not enough sieves being used (full stack required for the Column to lock).

agglomerate: natural tendency of materials to clump or ball together. This condition is very common in materials with high moisture, fat or oil content or those with fibrous or extremely irregular particle geometry.

aperture: the dimension defining an opening in a screening surface.

base/fines collector holder: Component of the Sonic Sifter stack assembly. This sturdy aluminum base holds the Fines Collector and is an anchor in which the Column Lock connects to during transfer.

blinding: plugging of the screen openings with particles either exactly the same size as the sieve opening or by fine particles which build up on the wire mesh and eventually close off the openings. Frequently referred to as pegging.

calibration test sieve: a test sieve manufactured using sieve cloth which has been inspected after being mounted in the sieve frame; and that meets the requirements of Standards Table in part based on the standard deviation of the required number of sample openings in the test sieve not exceeding the maximum allowable for a confidence level of 99.73 %.

column lock: Component of the Sonic Sifter stack assembly. This metal (aluminum and stainless steel) fixture’s arms locks on to the Base/Fines Collector Holder, holding the Stack Assembly together for it to be placed into the sifter’s Test Chamber. Once inside the Test Chamber, the locking arms are released and tension holds the Stack Assembly in place during testing. The arms are then reengaged with the Base/Fines Collector Holder so the Stack Assembly can be removed from the sifter safely after testing.

compliance test sieve: a test sieve manufactured using sieve cloth which has been inspected prior to being mounted in the sieve frame; and that meets the requirements of Standards Table in part based on the standard deviation of the required number of sample openings per 100 square feet of sieve cloth not exceeding the maximum allowable for a confidence level of 66 %.

cover: stamped or spun lid that tightly covers the top of a sieve to prevent the loss of the material sample during sifting or mechanical agitation.

crimp: the corrugation in the warp and shute wire. The crimp in the wires is formed either during the weaving process, or with a crimping machine prior to weaving. If formed during the weaving process, the tension existing between the warp and shute wires fundamentally determines the respective amount or depth of crimp, which locks the wires in place, and in part establishes the firmness of the sieve cloth.

diaphragm: Component of the Sonic Sifter stack assembly. This latex disk encloses/covers the particles within the top cone so they do not escape. During testing, the column of air caused by the sonic wave’s effect on the membrane assists in the trying of particles. Diaphragms inevitably wear out over time and have expiration dates.

electrostatic charges: accumulation of electrical charges on the particles and sieve components causing clinging, agglomeration or blinding. This condition is frequently seen in hydrocarbon-based materials, plastics, reactive metals, paint pigments and powders with a large fraction finer than 20 micrometers.

extended rim pan: a sieving pan with a skirt designed to nest within a sieve stack, allowing multiple tests to be performed simultaneously. Also called a "mid-stack pan" or "nesting pan."

fines collector: Component of the Sonic Sifter stack assembly. This Latex pouch at be bottom of the Stack and collects the finest particles. Fines collectors inevitably wear out over time and have expiration dates.

firmness: a subjective term referring to the planar rigidity of sieve cloth (as a roll good, not mounted in a test sieve frame), established by the tensile strength of the material, the relationship of the mesh to wire diameters, the type of weave, and amount of crimp in the wires. The absence of firmness in sieve cloth is termed sleaziness.

flow additive: powdered substance added to the sample to reduce agglomeration, neutralize static charges and improve the flow characteristics of the sample. Common additives are fine silica, activated charcoal, talc, and other commercially produced natural or synthetic substances. Generally, the additive is pre- screened to a known average particle size, blended with the sample (approximately 1% additive by weight) and then screened with the additives value removed from the reported data.

frame: a rigid sidewall used to form the body of the testing sieve. Common depths are 50.8 mm (2" full height) for 8” sieves and 25.4 mm (1" half height). Special application sieves of other depths are also in use.

inspection test sieve: a test sieve manufactured using sieve cloth which has been inspected after being mounted in the sieve frame; and that meets the requirements of Standards Table in part based on the standard deviation of the required number of sample openings in the test sieve not exceeding the maximum allowable for a confidence level of 99 %.

mesh: the number of wires or openings per linear inch (25.4 mm) counted from the center of any wire to a point exactly 1 in. (25.4 mm) distant, including the fractional distance between either thereof.

mid-stack pan:  Also called a "extended rim pan" or "nesting pan," this is a sieving pan with a skirt designed to nest within a sieve stack, allowing multiple tests to be performed simultaneously.

pan: stamped or spun receiver of materials passing through the finest sieve.

plain weave: sieve cloth in which the warp wires and shute wires pass over one and under one in both directions.

shute wires: the wires running the short way of, or across the cloth as woven (also referred to as the shoot, fill, or weft wires).

sieve cloth: woven wire cloth conforming to ASTM E11 specifications.

sieve: an apparatus for the purpose of sieving, consisting of a separating media mounted in a frame.

skirt: section of test sieve below the sieve mesh that allows for mating or nesting of the sieves in a test stack.

stack: sieves placed together in a single column used for particle separation. 

stack assembly: Used in Sonic sifter. Includes: 1 Column Lock, 1 Diaphragm, 1 Top Cone, 6 Acrylic Spacers (sieves not included), 1 Fines Collector, and 1 Fines Collector Holder.

support mesh: coarse sieve cloth mounted under fine sieve cloth in a test sieve to provide extra strength. This is widely used in wet sieving operations to protect the fragile fine sieve cloth. Frequently called backing cloth or rolled backing cloth.

test sieve: screening medium (mesh) with openings of uniform size and shape mounted on a rigid frame, usually for laboratory testing or small scale production applications. The frames can be made of various materials, the most common of which are brass and stainless steel in a cylindrical configuration, having a diameter of 3", 5", 6", 8", 10", 12" or larger.

top cone: Component of the Sonic Sifter stack assembly. Clear acrylic funnel-like ring provides a loading area for of the test sample. It also assists in directing the sonic waves down the Column to best try the particles.

twill weave: sieve cloth in which the warp wires and shute wires pass over two and under two wires in both directions.

warp wires: the wires running the long way of the cloth as woven.

wet sieving: the separation of fines from the coarse portion of a sample while suspended in an aqueous solution introduced to a testing sieve. The liquid medium is used to negate static charges, break down agglomerates and lubricate near-size particles. After the fines have been washed through the sieve, the residue is oven-dried and re-weighed.