Technical Info:
Calculation of open area

The sheet has a defined and constant open area %. This percentage of "open area" takes into consideration the total of the perforated surface, irrespective of the edges or filled areas. To calculate the weight of a sheet and ', therefore, necessary to consider only the perforated area and subsequently add, the solid regions.

Formulas for determining the percentage of open area and the number of holes per dm ²

ROUND HOLES OPEN AREA %

Legend:
N = number of holes dm ²
P = open area %
d = diameter of hole
i = distance (interaxis)

ROUND HOLES TRIANGULAR PITCH (Staggered at 60°)

Open Area %: P = 0.9 * (d² / i²)
Number of holes / DM² : N = (1.15 * 10⁴) / i²

ROUND HOLES TRIANGULAR PITCH (Staggered at 45°)

Open Area %: P = 1.57 * (d² / i²)
Number of holes / DM²: N = (2 * 10⁴) / i²

ROUND HOLES RECTANGULAR PITCH (Staggered at 90°)

Open Area % : P = 0.78 * (d² / i²)
Number of holes / DM²: N = 10⁴ / i²

SQUARE HOLES OPEN AREA %

Legend:
N = number of holes /dm ²
P = open area %
Q = Square size
i = distance (interaxis)

SQUARE HOLES IN PARALLEL LINE

Open area % : P = (Q / i²) * 100
Number of holes / DM²: N = 10⁴ / i²

SQUARE HOLES STAGGERED PITCH

Open area %: P = (Q / i²) * 100
Number of holes / DM²: N = 10⁴ / i²

SQUARE HOLE DIAGONAL LINE

Open area %: P = 2 * (Q / i²) ² * 100
Number of holes / DM²: N= (2 *10⁴ )  / i²

SLOT HOLES OPEN AREA

legend:
N = number of holes dm ²
P = open area % 
L = Long side size of oblong holeC = Short side size of oblong hole 
i = distance

SLOT HOLES PARALLEL LINE

Open area %: P= [ ( L-C ) * C + ( 0,785 * c²⁾ ] / ( x * z )

SLOT HOLES STAGGERED PITCH

Open area % : P= 2 *[ ( L-C ) * C + (0,785 * c²  ) / ( x * z )]

SLOT HOLES STAGGERED PITCH

Open area %: P= 2 *[ ( L-C ) * C + (0,785 * c²  ) / ( x * z )]