BS ISO 21250-1 pdf free download
BS ISO 21250-1-2020 pdf free download.Rolling bearings — Noise testing of rolling bearing greases Part 1: Basic principles, testing assembly and test machine.
This document specifies:
— basic principles, testing assembly and the test machine for noise testing of rolling bearing greases;
— symbols used in the test methods BQ+, MQ and NQ.
This document is applicable for testing rolling bearing greases, especially of unused grease.
NOTE Suitable greases are greases of NLGI classes 1 to 3 according to DIN 51818 [6] . Suitable greases for lubrication of rolling bearings are especially greases according to ISO 12924. The test method according to this document delivers meaningful results for rolling bearings; however, it can also be applied for greases in similar applications [12][13] .
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 492, Rolling bearings — Radial bearings — Geometrical product specifications (GPS) and tolerance values
ISO 5593, Rolling bearings — Vocabulary
ISO 5753-1, Rolling bearings — Internal clearance — Part 1: Radial internal clearance for radial bearings
ISO 15242-1:2015, Rolling bearings — Measuring methods for vibration — Part 1: Fundamentals
ISO 21250-2, Rolling bearings — Noise test of rolling bearing greases — Part 2: Test and evaluation method BQ+
ISO 21250-3, Rolling bearings — Noise test of rolling bearing greases — Part 3: Test and evaluation method MQ
ISO 21250-4, Rolling bearings — Noise test of rolling bearing greases — Part 4: Test and evaluation method NQ
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5593, ISO 15242-1 and the following 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 noise
vibration that is a random mechanical energy process of spectral density varying continuously with frequency and perceived as acoustic actions that are neither acoustic shocks nor a series of harmonic tones nor complex tones and which are substantially uniform over time
Note 1 to entry: Noise can be represented mathematically, that is as Fourier integral which can be expressed as the sum of a series of plain vibrations. Its distinguishing characteristic, as opposed to other acoustic actions with discrete frequencies, is a spectrum with irregular amplitudes of each frequency.
3.2 start-up noise
v SUN
noise (3.1) at the start of the bearing testing
3.3 noise level
v NL
noise (3.1) of the bearing calculated as the average value or rms of measuring points
Note 1 to entry: The number of measuring points and measuring time depend on the test method.
3.4 noise peak
v NP
peak value of the bearing noise (3.1)
3.5 peak count
number of peak signals exceeding a defined threshold level
3.6 calibrator
measurement standard that provides a sinusoidal vibration speed at certain frequencies and defined
amplitudes
3.7 grease damping
GD
attenuating effect of the lubricant, which is related to the vibration excitation of the bearing
4 Symbols, abbreviated terms and subscripts
The symbols and abbreviated terms contained in Table 1 and the subscripts contained in Table 2 apply to the noise testing of greases according to test methods BQ+, MQ and N.BS ISO 21250-1 pdf download.
