Industrial Perforated Plate Screens Requirement and Test Procedure
Perforated metal plate for industrial screening purposes is supplied in flat or coiled form, in various hole shapes with a maximum plate thickness of 12.5 mm. Below is the test Procedure and requirements of industrial plate screens.
Industrial perforated plate screens test requirement
Hole size and pitch
The tolerances on the hole size and the pitch of both round and square holes are specified in ISO 7805-1 for perforated plate of thickness of 3 mm and above, and in ISO 7805-2 for perforated plate of thickness below 3 mm.
Plate thickness
The plate thickness shall be less than the nominal hole size and less than the bridge width (bar).
Plate width and length
The tolerances on plate width a1 and plate length b1, for plates cut on all edges are given in table 1.
| Nominal Width or Length a1, or b1 | Tolerance on a1, or b1, for Nominal Plate and Thickness t | |||
|---|---|---|---|---|
| t ≤ 3 | 3 < t ≤ 5 | 5 < t ≤ 10 | 10 < t ≤ 12.5 | |
| a1, or b1 ≤ 100 | ±0.8 | ±1.1 | ±1.5 | ±2 |
| 100 < a1, or b1 ≤ 300 | ±1.2 | ±1.6 | ±2 | ±3 |
| 300 < a1, or b1 ≤ 1000 | ±2 | ±2.5 | ±3 | ±4 |
| 1000 < a1, or b1 ≤ 2000 | ±3 | ±4 | ±5 | ±6 |
| 2000 < a1, or b1 ≤ 4000 | ±4 | ±6 | ±8 | ±10 |
| 4000 < a1, or b1 | ±5 | ±8 | ±10 | ±12 |
Squareness
The departure from squareness, c, generally referred to as the "amount out-of-square", of cut perforated metal plates is quantified by the orthogonal projection of a transverse edge (plate width a1,) onto a longitudinal edge (plate length b1,). It is expressed as a percentage of a1.
Percent out-of-square = 100c/a1
| Nominal Plate Thickness, t, mm | Tolerance on Squareness as A Percentage of a1 |
|---|---|
| t ≤ 3 | 0.75 |
| 3 < t ≤ 5 | 1.5 |
| 5 < t ≤ 10 | 3 |
| 10 < t ≤ 12.5 | 5 |
Width of margins
The tolerances on the width of margins e and f are given in table 3.
| Nominal Pitch, p | Tolerance on Width of Margins e, f |
|---|---|
| P ≤ 5, open area ≤ 25% | ±5 |
| p ≤ 5, open area > 25 % | ±10 |
| 5 < p ≤ 20 | ±10 |
| 20 < p | ±0.5p |
Flatness
The tolerances on the flatness of perforated metal plates, roller-levelled after perforation, as given in table 4, apply for plates
- With a maximum length of 2000 mm;
- With margins not exceeding plate thickness t + 0.5p;
- With open areas in the range of 20% to 40%.
| Nominal Width or Length a1, or b1 | Tolerance on Flatness, for Nominal Plate and Thickness t | ||||
|---|---|---|---|---|---|
| t < 0.7 | 0.7 ≤ t < 1.2 | 1.2 ≤ t < 3 | 3 ≤ t < 5 | 5 ≤ t < 12.5 | |
| a1, or b1 ≤ 1200 | 20 | 18 | 15 | 12 | 10 |
| 1200 < a1, or b1 ≤ 1500 | 28 | 22 | 18 | 16 | 14 |
| 1500 < a1, or b1 ≤ 2000 | 30 | 25 | 20 | 16 | 14 |
Industrial perforated plate screens test procedure
Hole size and pitch
Measure the hole size and pitch according to ISO 7805-1 or ISO 7805-2, depending on the plate thickness. The measurements shall be taken on the punch side of the plate.
Figure 1: Hole size w and pitch p.
Plate width and length
Measure the plate width and length with a scale graduated in millimetres. For dimensions of 300 mm or less, a vernier calliper may be employed. Take the measurement over the entire thickness t.
Figure 2: Perforated plate wide and length
Squareness
If applicable, determine the squareness of cut perforated metal plates by measuring the plate width and length and the amount out-of-square c. Identify the dimension c with the aid of a try square.
Figure 3: Measurement of amount out-of-square
Flatness
Place the plate, punch side uppermost, on a flat reference surface, e.g. a table with a smooth and even top. Use a scale, graduated in millimetres, which does not flatten the plate, to measure the distance from the highest point of the plate to the reference surface.