Direction of Expanded Metal
A-Side in the direction of expansion
A-Side against the direction of expansion
B-Side in the direction of expansion
B-Side against the direction of expansion
Flat Rolling
Also known as to calendar, flattening is a secondary process that reduces the overall thickness of the mesh. Flattening takes on four primary processes that vary from manufacturer to manufacturer, Niles uses the following:
FXM Straight Rolled – Flattening parallel to LWD, the result of passing (feeding) the standard material through a cold roll reducing mill to a defined specification that produces a uniform thickness of the entire sheet. The material elongates parallel to the feed direction creating a longer sheet in the feed direction and may reduce the size of the of the sheet opposite of the feed direction.
FXM Cross Rolled – Flattening parallel to SWD
Semi-Flat -The result of passing (feeding) the standard material through a cold roll reducing mill to a defined specification that produces a less than uniform thickness of the entire sheet. The product is not flat by definition but somewhere between standard and flat.
Touch Pass -The result of passing (feeding) the standard material through a cold roll reducing mill to slightly knock down the Bond.
Diagram of flat-rolling process
Expanded Metal before flat-rolling
Expanded metal after flat rolling
Shearing
Expanded metal can be sheared to different specifications
RANDOM SHEARING: Results in open diamond design and angle, leaving jagged edges and prongs in most cases. A closer tolerance is obtained at a normal mill tolerance for standard and flattened expanded metal of +/- 1/16” and +/- 1/4” on grating and catwalk.
BOND SHEARING: Results in closed diamond design and angle, eliminating jagged edges and prongs. Shearing cuts through expanded metal at center of bond, where strands intersect. Standard expanded metal should not be bond sheared SWD. SWD and LWD tolerances are greater at +/- 1/2 design size.
BALANCE SHEARING: LWD only – expanded to SWD dimension. Provides matching sections for continuous catwalk and flooring applications. Closed diamonds SWD, cut with either open or closed diamonds to obtain ordered length LWD.
CENTERLINE SHEARING: Finished piece symmetrical, around a row of diamonds at center of piece. Open diamonds both SWD and LWD.
Levelness, Square, & Camber
Expanded metal can be curved on 3 axes
CAMBER: Bowing in sheet or coil is measured by placing a straight edge along the concave side of the metal, parallel to the LWD, touching both ends of the sheet.
LEVELNESS: When placed on a flat surface with the curvature facing upwards, the greatest distance between the sheet and the flat surface.
Calculator
SWD (Short Way Design): The short dimension of the diamond opening, measured from the center of one bond to the center of the next.
LWD (Long Way Design): The long dimension of the diamond opening, measured from the center of one bond to the center of the next.
SWM (Short Way Mesh): The dimensional (US/Metric) size of the sheet or coil measured across the short way of the opening.
LWM (Long Way Mesh): The dimensional (US/Metric) size of the sheet or coil measured along the long way of the opening.
Mesh per Inch
MPI is measured with SWD (Short Way Design)
Openings per square inch: SWD MPI x LWD MPI x 2
In this illustrated example the calculation would be: 4 x 2.5 x 2 = 20