Standard No.:	GB/T 42539-2023
English Name:	Rolling bearings—Ceramic bearings balls—Determination of the strength by notched ball test
Chinese Name:	滚动轴承 轴承用陶瓷球 强度测定（缺口球试验）
Chinese Classification:	J11    Rolling bearing
Professional Classification:	GB    National Standard
ICS Classification:	21.100.20 21.100.20    Rolling bearings 21.100.20
Source Content Issued by:	SAMR; SAC
Issued on:	2023-05-23
Implemented on:	2023-12-1
Status:	valid
Target Language:	English
File Format:	PDF
Word Count:	15500 words
Translation Price(USD):	465.0
Delivery:	via email in 1~3 business day

GB/T 42539-2023 Rolling bearings - Ceramic bearings balls - Determination of the strength by notched ball test 1 Scope This document specifies a method for the determination of the strength of finished ceramic balls for ball bearings, preferably made of silicon nitride (Si₃N₄), with ball diameters from 3 mm to 50 mm. Note 1: ISO 26602 specifies the requirements for preprocessed silicon nitride materials for rolling bearing balls. ISO 3290-2 specifies requirements for finished silicon nitride balls for rolling bearings. Note 2: Other test methods to determine ceramic ball strength can be found in Reference. The results of the strength tests slightly depend on the Poisson's ratio. For this reason, all calculations are restricted to a Poisson's ratio ranging from 0.15 to 0.35. This includes the Poisson's ratio of a typical silicon nitride ceramic used as rolling element in ball bearings. The method can also be used for rolling bearing balls made of other ceramic materials, but the reported prefactors may not be valid. Note 3: Poisson's ratio of isotropic materials can be determined by one of the methods given in ISO 17561. Because of the (defect controlled) brittle fracture behaviour of ceramic materials, a significant scatter of individual results in the characterization of a series of nominally identical samples can occur. Note 4: A further statistical analysis according to ISO 20501 can be carried out. 2 Normative references The following referenced documents are indispensable for the application 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 463 Geometrical product specifications (GPS) - Dimensional measuring equipment - Design and metrological characteristics of mechanical dial gauge Note: GB/T 39547-2020 Design and metrological characteristics of mechanical dial gauges (ISO 463 : 2006, IDT) ISO 3290-2 Rolling bearings - Balls- Part 2: Ceramic balls Note: GB/T 308.2-2010 Rolling bearings - Balls - Part 2 : Ceramic balls (ISO 3290-2:2008, IDT) ISO 3611 Geometrical product specifications (GPS) - Dimensional measuring equipment : Micrometers for external measurements - Design and metrological characteristics] ISO 6106 Abrasive products- Checking the grain size of superabrasives Note: GB/T 6406-2016 Superabrasive - Checking the grain size (ISO 6106 : 2013, MOD) ISO 7500-1:2018 Metallic materials - Calibration and verification of static uniaxial testing Machines - Part 1: Tension / compression testing machines- Calibration and verification of the force- measuring system Note: GB/T 16825.1-2008 Verification of static uniaxial testing machines - Part 1 : Tension/compression testing machines - Verification and calibration of the force-measuring system (ISO 7500-1 : 2004, IDT) ISO 20501 Fine ceramics (advanced ceramics, advanced technical ceramics) - Weibull statistics for strength data Note: GB/T 40005-2021 Weibull statistics for strength data of fine ceramics (ISO 20501:2019, MOD) 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: - ISO Online browsing platform: available at https://www.iso.org/obp - IEC Electropedia : available at http://www.electropedia.org/ 3.1 equatorial plane plane of symmetry of the ball perpendicular to the loading direction 3.2 fracture force F applied force at fracture 3.3 ligament cross section remaining segment of a circle in the equatorial plane of the notched ball 3.4 ligament thickness h maximum thickness of the ligament cross section in the equatorial plane (3.1) between the notch root (3.13) and the ball surface Note: See Figure 1 and Figure 2. 3.5 mean notch root radius Rm arithmetic average of the notch root radii (3.10) R₁ and R₂ 3.6 nominal width of the cutting wheel wnom width of the cutting tool as declared by the producer 3.7 notch centricity z quantifiable value of departure from perfect notch midplane, related to the equatorial plane Note: Practically, the asymmetry of the notch is determined as the notch centricity z; see Figure 2. 3.8 notch depth l theoretical depth of the notch Note 1: I=Dw-h. Note 2: See Figure 2. 3.9 notch midplane imaginary plane through the centre of the real notch perpendicular to the loading direction Note : See Figure 1 and Figure 2.