This standard delineates the specifications for industrial sieves crafted from perforated plates, including detailed requirements for aperture dimensions, shapes, spacing patterns, thicknesses, and material criteria. It serves as a guideline for designers, manufacturers, and quality controllers engaged in the production and inspection of perforated plates used in industrial screening applications.
Overview
This standard delineates the specifications for industrial sieves crafted from perforated plates, including detailed requirements for aperture dimensions, shapes, spacing patterns, thicknesses, and material criteria. It serves as a guideline for designers, manufacturers, and quality controllers engaged in the production and inspection of perforated plates used in industrial screening applications.
Audience
Contents
Structure
This section covers industrial perforated plates featuring circular or square apertures. It defines critical parameters such as aperture dimensions, spacing (pitch), plate thickness, and allowable tolerances. Plates with various pitch-to-aperture ratios and thickness ranges are included under this scope.
Clarifies key terms related to perforated plates used in industrial sieving, including aperture (opening size), pitch (center-to-center distance between apertures), and their significance in performance and manufacturing consistency.
Describes the method for identifying plates based on aperture size and shape, aperture arrangement (such as staggered or square patterns), plate thickness, and material composition. Includes preferred aperture-pitch combinations and labeling requirements.
Outlines material criteria and provides recommended thickness ranges relative to aperture dimensions and pitch-to-aperture ratios. Emphasizes thickness measurement prior to perforation and presents tabulated thickness ranges for different aperture sizes.
Details the shapes of apertures (round and square) and their arrangement patterns including 60° staggered and in-line layouts. Defines preferred pitch-to-aperture ratios affecting open area percentages and provides relevant tabulated data.
Specifies how to measure pitch on the punch side of the plate, calculation of average pitch and aperture size from multiple measurements, and the minimum number of samples required for accurate evaluation.
Defines allowable variations in average and individual aperture sizes and pitch dimensions based on nominal values. Includes tabulated tolerance limits and guidelines for ensuring manufacturing precision.
Describes sampling plans for lot inspection based on Level IV sampling per IS 2500 Part I, acceptance quality levels, and procedures for evaluating defective samples to decide lot acceptance or rejection.
Summarizes quality acceptance benchmarks including sampling size, defect definitions, and acceptance limits according to AQL 2.5%. Provides procedural guidance for quality control and lot conformity assessment.
Frequently Asked
The standard specifies both round and square apertures for industrial perforated plates. Aperture sizes comply with the R20 preferred number series as per ISO 2194, with pitch-to-aperture ratios of 1.25, 1.4, 1.6, 1.8, and 2.0 defining five classes of plates with nominal open areas ranging approximately from 64% to 23%. For square holes, the maximum corner radius is calculated using the formula r_max = 0.05 × A + 0.30 mm, where A is the aperture size in millimeters.
Pitch is defined as the center-to-center distance between adjacent apertures and is measured on the punch side of the perforated plate. To determine the average pitch, multiple measurements are taken, with the minimum sample size (N) calculated by the formula N = 2 + (100 / A²), where A is the aperture size in millimeters (integer part used if fractional). This method ensures accurate assessment of pitch dimensions.
The standard outlines specific tolerance limits for both aperture size and pitch. Average aperture size tolerances typically range from ±0.1 mm to ±0.5 mm depending on nominal size, with individual aperture tolerances approximately double the average. Pitch tolerances similarly vary, with average pitch tolerances typically between ±0.2 mm and ±0.7 mm. These tolerances ensure dimensional accuracy and uniformity of perforation patterns.
Mild steel is the standard material specified for industrial perforated plates. Plate thickness is recommended based on aperture size and pitch-to-aperture ratio, with thickness ranges provided for various aperture size intervals. For example, apertures from 125 mm down to 100 mm require thicknesses between 3.15 mm and 25 mm, while smaller apertures such as 12.5 mm down to 8 mm range from 1.25 mm to 8 mm thickness. These guidelines maintain structural integrity and performance.
Sampling should be conducted following Level IV sampling plans as per IS 2500 (Part I)-1973, selecting an appropriate number of perforated plates from each lot. All sampled plates are inspected for compliance with specified requirements. Any plate failing any criterion is deemed defective. Lot acceptance is determined using an Acceptable Quality Level (AQL) of 2.5%, referencing IS 2500 attribute sampling tables to decide acceptance or rejection based on defective counts.
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