ABMA 18.2:1982 pdf download

ABMA 18.2:1982 pdf download.Needle Roller Bearings Radial, Inch Design
1. SCOPE
This standard for Inch Design Industrial Radial Needle Roller Bearings and components includes: Identification Code Boundary Dimensions Bearing Tolerances Fitting and Mounting Practice Airframe Needle Roller Bearings, Needle Roller Thrust Bearings, and bearings of other types are covered in separate ABMA-ANSI Standards.
2. IDENTIFICATION CODE
2.1 General. This code identifies and, as far as possible, describes each needle roller bearing or component on the basis of complete dimensional and functional interchangeability. This code establishes a universal language for describing and identifying bearings and components in order to facilitate communications between the user and the manufacturer. The code is also intended to simplify the handling by user personnel of identical bearings made by different manufacturers, whose identification numbers may be different and difficult to interpret. This code applies only to those radial needle roller bearings or components whose boundary dimensions and tolerances conform to this standard.2.2 Structure of Code. As shown in the following table, Schematic Arrangement of a Complete Code Number, the code consists of three sections. Section 1 , called the Basic Number, includes a diameter symbol made up of a group of numerals, followed by a type symbol made up of a group of letters and finally by a dimension series symbol made up of a group of numerals. This Basic Number must always be used. Sections 2 and 3 delineate modification of design and lubricants and, if required to complete the identification, consist of additional letters. In the Schematic Arrangement Tables, “O” represents any code numeral and “A” represents any code letter.The Diameter is indicated by two or three numerals comprising the diameter symbol as shown in Boundary Dimension Tables 3.1 -3.6. The Type is indicated by two, three or four letters comprising the type symbol shown in 2.2.2. The Dimension Series is indicated by two numerals. The first numeral indicates the width series and the second, the diameter series. Both are shown in Boundary Dimension Tables 3.1 -3.6. 2.2.2 Bearing and Component Type Symbols
4. BEARING AND COMPONENTS TOLERANCES
4.1 General The tolerance limits for inch design bearings and components are based upon long-established practice. 4.2 Tolerance Definitions and Gaging Practice. Definitions of most terms used in the tolerance limit tables as well as gaging practices are covered in ANSI Standard B3.4—ABMA Standard 4. Terms not defined in ANSI Standard B3.4—ABMA Standard 4 are explained in the tolerance limit tables.
5. FITTING AND MOUNTING PRACTICE
5.1 General. This section covers needle roller bearing and component fitting and mounting practice for normal operating conditions. Tables 5.1 – 5.8 list the tolerance limits required for shaft and housing seat diameters for bearings with inner and outer rings as well as limits for raceway diameters where inner and/or outer rings are omitted and the rollers operate directly upon these surfaces. Unusual design and operating conditions may require a departure from these practices. In such cases, bearing manufacturers should be consulted. 5.2 Needle Roller Bearings, Drawn Cup, without inner ring, Types NIB, NIBM, NIY, NIYM, NIH, NIHM. 5.2.1 Housings. Drawn cup needle roller bearings depend on the housings into which they are pressed for their sizes and shapes. Therefore, the housings must not only have the proper bore dimensions but also must have sufficient strength. Tables 5.1-5.2 show the bore tolerance limits for rigid housings such as those made from good quality cast iron or steel of adequate radial section equal to or greater than the ring gauge section given in ANSI Standard B3.4—ABMA Standard 4. Consult the bearing manufacturers for recommendations if the housings must be of lower strength materials such as aluminum or even of steel of thin radial section. The dimensions of the housing bores shall be such that when the mean bore diameter of a housing is measured in each of several radial planes, the maximum difference between these mean diameters shall not exceed 0.01 3 mm (0.0005 inch) or one-half the housing bore tolerance limit, if smaller. Also, the radial deviation from circular form shall not exceed 0.006 mm (0.00025 inch). The arithmetic mean surface roughness (Ra) shall not exceed 3.2 micrometres (1 25 micro-inches).