GB/T 2688-2012Plain bearings - Technical specification for powder metallurgy bearings (English PDF)

Foreword

This standard rule according to GB/T 1.1-2009 given draft. This standard replaces GB/T 2688-1981 "Powder metallurgy plain bearing technical condition." Compared with the GB/T 2688-1981, The main technical changes are as follows:

--- Standard format in accordance with GB/T

1.1 claim rearrange;

--- Increasing the normative references;

--- Revised Table 1, Table 2 powder metallurgy method of marking an increase of iron-based and copper-bearing species;

--- Table 2 and Table A.3 in the unit "kgf/mm2" to "MPa";

--- Normative Appendix A bearing surface roughness by the " 7" to "<=Ra1.6". The standard proposed by China Machinery Industry Federation. This standard sliding bearing by the National Standardization Technical Committee (SAC/TC236) centralized. This standard is drafted by: The machine Productivity Promotion Center, Hefei Bolin Advanced Materials Co., Ltd. Participated in the drafting of this standard. Hefei University, Lin'an Oriental Bearing Co., Ltd. This standard replaces the standards previously issued as follows:

--- GB/T 2688-1981. Powder metallurgy plain bearing Technical conditions

1 Scope

China's national technical specification for powder metallurgy plain bearings. It specifies the technical conditions for the sintered bearings whose types and dimensions are given in GB/T 18323, and it applies to copper-based and iron-based powder metallurgy bearings. A sintered bearing is a bearing with a reservoir inside it. The bush is pressed from metal powder and sintered rather than machined from solid, which leaves a controlled interconnected porosity of around a quarter of its volume, and that porosity is filled with oil under vacuum. In service the shaft draws oil out of the pores into the running clearance by capillary action and by the local heating and pressure, and when the shaft stops the oil is drawn back in. The bearing lubricates itself for years without attention, which is why it is used in the tens of millions in small motors, domestic appliances, power tools, office machines, fans and automotive auxiliaries. The specification therefore addresses the properties of a porous body rather than of a solid one: the material grades and their composition, the density, the interconnected porosity and the oil content, the radial crushing strength by which the strength of a sintered bush is measured, the dimensional tolerances and geometry after sizing, and the surface finish and appearance of the bore. The 2012 edition rearranges the document to the current drafting rules, adds normative references, revises the designation tables and adds iron-based and copper-bearing grades, converts the strength units from kilogram-force per square millimetre to megapascals, and expresses the bore surface roughness as a numerical Ra limit instead of the older triangle symbol. Issued on 11 May 2012 and in force since 1 December 2012, it replaces GB/T 2688-1981.

This standard specifies the technical conditions for powder metallurgy bearing GB/T 18323 prescribed. This standard applies to copper-based and iron-based powder metallurgy bearings.

2 Normative references

The following documents for the application of this document is essential. For dated references, only the dated edition applies to this article Member. For undated references, the latest edition (including any amendments) applies to this document.

GB/T 223 (all parts), steel and alloy chemical analysis method

GB 443-1989 L-AN Total loss system oil

GB/T 1800.1-2009 Geometrical product specifications (GPS) limits and fits - Part 1. Tolerances, deviations and fits basis

GB/T 1800.2-2009 Geometrical product specifications (GPS) limits and fits - Part 2. Standard tolerance grades and holes and shafts Limit deviations

GB/T 1958-2004 Geometrical Product Specifications (GPS) shape and position tolerance testing requirements

GB/T 5163-2006 sintered metal materials (excluding carbide) Permeable sintered metal material density, oil content and open Determination of porosity Determination of strength

GB/T 6804-2008 sintered metal bushing radial crushing Determination of apparent hardness of the first part of the

GB/T 9097.1-2002 sintered metal materials (excluding hardmetal). a cross-sectional hardness of the matrix The uniform material

GB/T 10425-2002 sintered metal friction materials - Determination of apparent hardness

GB/T 18323-2001 sintered sliding bearing bushes - Dimensions and tolerances

3 Technical requirements

3.1 bearing material classification according to alloy composition and density, according to the provisions in Table 1. Table

1 Classification of the base class base alloy No. Classification Classification Grade mark oil density/(g/cm3) Iron-based