Plastic mesh is made using a variety of unique extrusion and/or expansion processes to produce a wide range of apertures (hole sizes), weights, and thicknesses.
Extrusion is a continuous process in which plastic resin pellets are melted and pushed through a die in "meat-grinder" fashion to create a continuous mesh. Extruded netting can be produced in a wide range of configurations ranging from fine filtration-grade netting (resembling woven fabric) to a more coarse extrusion typical of plastic construction fencing.
Diamond Mesh Netting is extruded using counter-rotating dies. Joints are formed when two strands intersect or overlay each other forming a diamond pattern. Two distinct planes (known as flow channels in some applications) are created when the opposing strands overlap. Tooling and processing conditions can create diamond mesh nets with angles ranging from 40 degrees to 105 degrees.
Square Mesh Netting is extruded using a circular oscillating die plate. Longitudinal strands are determined by the size of the holes around the circumference of the die plate. Cross strands are created when the die plate opens, creating an integral joint structure along the x and y plane. Square mesh netting typically has one flat side created by the hot extruded mesh tube passing over a mandrel.
Oriented Netting is produced in a secondary operation by heating and stretching extruded square mesh netting to create a lighter-weight material with higher strength to weight ratios. Bi-axial orientation typically "stretches" the original extrusion by 3 to 4 times the original width and length.
Expanded Mesh is produced by slitting plastic sheet stock in a controlled pattern, then stretching or expanding the width to produce the designated nominal aperture (hole) size. Dimensional measurements for expanded mesh are somewhat different than extruded and oriented mesh (see diagram to right).
PMSF: The nominal weight of Extruded and Oriented nets are most commonly identified in PMSF or pounds per 1000 square feet.
Woven Mesh Fabrics are produced by weaving monofilament fibers using advanced looms and finishing equipment. The mesh opening for a given strand thickness is dictated by controlling the threads per inch (weft mesh count and warp mesh count). See diagram at left for a representation of mesh parameters.