BS ISO 3547-7:2020 pdf download – Plain bearings — Wrapped bushes Part 7: Measurement of wall thickness of thin-walled bushes
This document describes, following ISO 12301, the checking methods and measuring equipment used for measuring the total wall thickness of thin-walled bushes in the finished state.
NOTE All dimensions in this document are given in millimetres.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 12301, Plain bearings — Quality control techniques and inspection of geometrical and material quality characteristics
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
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radial distance between the opposing measuring points at the inner and outer cylindrical surface Note 1 to entry: See Figure 1.
4 Symbols and units
For the purposes of this document, the symbols and units given in Table 1 apply.
5 Purpose of checking
The purpose of checking is to ensure that the wall thickness and wall thickness tolerances are in accordance with ISO 3547-1. If this measurement is required, it is designated by s 3 ; see ISO 3547-1.
6 Checking methods
6.1 Measuring principle
The gauging axis of the measuring device shall be in the radial direction and perpendicular to the outside surface of the test piece in order to find the minimum value of the wall thickness. The measured values may be recorded by a single measurement or by a sum measurement, as represented symbolically in Figure 2.
The presence of lubricating holes, oil pockets, oil grooves, markings or special chamfers can require deviation from the measuring lines and measuring points specified in 6.2 and 6.3. Any such deviation shall be agreed between customer and supplier. Any wall thickness not conforming to the specified values due to the manufacturing process, because of deformation of the bearing backing in the area of marking or at non-load-bearings places of wrapped bushes, shall be agreed between customer and supplier.
6.2 Line measurement around the circumference Continuous measurement of the wall thickness around the circumference shall be carried out at the measuring lines specified in Figure 3 and Table 2.
6.3 Point measurement
Point-by-point measurement of wall thickness shall be carried out at the measuring points specified in Figure 4 for widths of B ≤ 90 mm and outside diameter D o ≤ 150 mm. In the case where B > 90 mm and D o > 150 mm, the measurement method shall be subject to agreement between the supplier and user. The measuring position distance, a ch , shall be taken from Table 2.
7 Requirements for measuring equipment for the contact method
7.1 Radius of the measuring pin on the outside surface
The radius of the measuring pin positioned on the outside as shown in Figure 5 shall be 1,5 mm ± 0,2 mm.
7.2 Radius of the measuring pin on the inside surface
The radius of the measuring pin positioned on the inside surface is given in Table 3 as a function of the bush outside diameter D o and the bearing material.
7.3 Measuring pin load
The measuring pin load, F pin , applied onto the sliding layer, shall be 0,8 N to 2,5 N in accordance with ISO 12301.
8 Checking of measuring equipment
The measuring equipment shall be checked for measurement uncertainty at a frequency specified by the user, based on the type of equipment and on experience from previous checks. The limits shall comply with the current industry requirements.BS ISO 3547-7 pdf download.