Ordering the same aperture when replacing screen cloth is not enough to preserve the same screening conditions. A change in wire thickness also changes the proportion of openings through which material can pass. Screen cloth open area quantifies that difference. However, the calculated percentage is not a throughput in tonnes per hour. This guide explains the calculation for square woven cloth and the limits to check when purchasing it.
Specify aperture and wire diameter separately
Aperture a is the clear distance between the inner edges of neighbouring wires, not their centre-to-centre distance. With wire diameter d, the repeating pitch is a + d. For square woven cloth with equal apertures and equal wire diameters in both directions, a repeating cell has area (a + d)² and its opening has area a². This separates the area occupied by wire from the area available for passage.
The geometric open-area percentage is φ = 100 × [a / (a + d)]². Enter a and d in the same length unit; the result is a percentage. This represents the planar projection of clean, regular, undamaged cloth. Do not apply this square-mesh expression directly to elongated openings, cloth woven with different wire diameters, perforated plate or polyurethane panels; their own geometry and manufacturer data are needed.
Two wire diameters at the same aperture
As an example, keep aperture a = 1.0 mm fixed. With d = 0.5 mm, φ = 100 × (1.0 / 1.5)² ≈ 44.4%. When wire diameter becomes d = 0.8 mm, φ = 100 × (1.0 / 1.8)² ≈ 30.9%. These are hypothetical dimensions illustrating the method, not a recommendation for a particular Metkan model or a statement of available cloth combinations.
Although the aperture is unchanged, the difference is about 13.5 percentage points. This does not mean throughput will fall by the same proportion. Thinner wire leaves more geometric opening, but mechanical suitability, wear, impact loading and attachment conditions require separate assessment. The cloth with the highest open area is not necessarily the right choice for every material and screen. Deciding on opening percentage alone can overlook maintenance needs or product quality.
| Aperture a | Wire diameter d | Calculated open area |
|---|---|---|
| 1.0 mm | 0.5 mm | 44.4% (calculated) |
| 1.0 mm | 0.8 mm | 30.9% (calculated) |
Cloth open area is not the usable deck area
Frames, supports, edge strips and blank sections can reduce the free surface of the complete deck. Suppose total deck area is 2.0 m² and supports and edges obstruct 10% of that footprint. If all of the remaining 90% carries cloth with 44.4% open area, approximate geometric passing area is 2.0 × 0.90 × 44.4 / 100 ≈ 0.80 m². This is area accounting for a clean surface, not a production-capacity calculation.
Do not subtract the same loss twice. If the panel manufacturer's net-area figure already excludes supports, applying another support factor is incorrect. Material accumulation and blocked apertures also change over time; the geometric value for clean cloth does not include them. In a site comparison, record both cloth specifications and the distribution of blocked openings. Do not treat one clean patch in a photograph as representative of the whole deck.
Check the effect under production conditions
After a cloth change, do not judge the outcome solely by tonnes passing through. Record feed size distribution, moisture, hourly loading, deck inclination and existing vibration settings under comparable conditions. Track both fines-product purity and recovery of the target fine particles; more material passing is not automatically better classification. When particle size is close to the aperture, small changes in the feed distribution can also affect comparisons. Explain the sampling conditions behind before-and-after results.
Measure or inspect cloth within the site's authorized maintenance and sampling arrangements. Do not reach towards an operating screen to take measurements. Define the measurement method and acceptance tolerance in the purchase specification; one aperture measurement cannot establish conformity of a complete panel. An open-area calculation does not correct tears, deformation or tension problems. Establish the physical condition first, then evaluate clean and comparable surfaces.
Do not order merely “the same screen cloth”
ISO 4783-2 identifies woven cloth using aperture, wire diameter, material and weave type together. ASTM E2016 addresses technical requirements for industrial woven cloth; laboratory test-sieve cloth is outside that scope. These distinctions explain why ordering by mesh count or aperture alone can be incomplete. The calculation here is not a declaration of conformity; the applicable specification edition and tolerances must be established separately.
When discussing a vibrating screen or micronized crushing-and-screening line with Metkan, share existing panel dimensions, aperture, wire diameter, support layout and attachment type. Together with feed analysis and target product limits, these details connect media selection to the complete machine. Review the product and plant pages below and send your existing screen details through the contact page. The cover is an AI-generated illustration, not a dimensioned drawing, actual Metkan product or customer installation.
Sources and calculation limits
Sources checked on 20 October 2026. Official scope descriptions were used; no full standard text or conformity test is provided. The area calculation is derived from square-cell geometry. Numerical examples are hypothetical, not measured field performance.
