ISO 11562

ISO 11562. It is an international standard published by the International Organization for Standardization that specifies the phase correct filtering method for the measurement of surface texture using profile methods. The standard defines the characteristics and application of a morphological filter, known as the Motif filter, used primarily for evaluating roughness profiles by separating waviness components. This technique is critical for ensuring consistent and comparable surface finish measurements in precision manufacturing and metrology across global industries.

Overview

The standard, developed under the purview of ISO/TC 213, provides a normative framework for filtering metrological data obtained from instruments like contact stylus profilometers. It establishes the mathematical basis for the Motif filter, which operates on the principle of identifying and merging local peaks and valleys, or motifs, within a measured profile. This approach differs from the Gaussian filters defined in other standards like ISO 16610-21, offering an alternative method for profile segmentation that is particularly robust against isolated outliers or deep scratches. The publication of this standard was a significant step in harmonizing surface texture analysis, complementing the foundational definitions found in ISO 4287.

Scope and purpose

The scope of the standard is confined to the phase correct filtering of two-dimensional profile data for the assessment of surface roughness. Its primary purpose is to define a procedure that minimizes phase distortion, which can alter the perceived location of profile features, thereby ensuring that the filtered profile accurately represents the actual surface geometry. This is essential for functional correlation in applications such as predicting the wear characteristics of piston rings or the sealing performance of gasket surfaces. The standard aims to provide manufacturers, quality control laboratories, and research institutions with a reliable and repeatable method to isolate the roughness component from the total measured profile for subsequent parameter calculation.

Key definitions and parameters

The standard introduces and formalizes several key concepts central to its application. The fundamental element is the "motif," defined as a portion of the profile between two consecutive peaks. The procedure involves rules for combining adjacent motifs based on specified criteria, including a threshold value often linked to the percentage of the Rz (parameter) roughness parameter. Other critical parameters defined include the evaluation length and the nesting index, which controls the scale of filtering. These definitions work in concert with those in companion standards like ISO 4287 for amplitude parameters and ISO 13565-2 for characterizing stratified surfaces, ensuring a cohesive terminology across the field of surface metrology.

Measurement procedure and filtering

The measurement procedure begins with acquiring a primary profile using an instrument calibrated according to standards such as ISO 3274. This raw data is then processed using the Motif filter algorithm as specified. The step-by-step filtering process involves identifying all local peaks and valleys, constructing initial motifs, and then iteratively merging motifs that do not exceed a defined height criterion. This sequential process continues until no further merges are possible, resulting in a filtered roughness profile. The output is used for calculating standardized roughness parameters, ensuring compatibility with data processed in different laboratories or with different software implementations, a concern often addressed by bodies like the American Society of Mechanical Engineers.

Applications and industry relevance

This standard finds significant application in industries where surface texture is a critical functional attribute. In the automotive industry, it is used to analyze cylinder liner surfaces and crankshaft journals. The aerospace industry applies it to turbine blade roots and aerodynamic surfaces. Manufacturers of bearing (mechanical)s and hydraulic seals rely on its filtering method to correlate roughness measurements with performance and longevity. The Motif filter's resistance to distortion from non-typical features makes it particularly valuable for analyzing surfaces from processes like honing (metalworking) or electrical discharge machining, where traditional Gaussian filters might provide misleading results.

Relationship to other standards

ISO 11562 is an integral part of a larger family of ISO geometric product specifications (GPS) standards concerning surface texture. It interacts directly with ISO 4288, which provides rules and procedures for the condition of measurement and evaluation. Its filtering methodology is an alternative to the Gaussian regression filter specified in the ISO 16610 series. Furthermore, it supports the calculation of parameters defined in ISO 13565-1 for surfaces having stratified functional properties. The standard's principles have also influenced national standards bodies, including Deutsches Institut für Normung (DIN) and the Japanese Industrial Standards (JIS) committee, promoting international alignment in precision engineering and metrology. Category:ISO standards Category:Geometric dimensioning and tolerancing Category:Metrology