SAE ARP 5448 7A-2016 Plain Bearing Wear Measurement.pdf

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1、_ 6$(7HFKQLFDO6WDQGDUGV%RDUG5XOHVSURYLGHWKDW7K is report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefrom, is

2、 thHVROHUHVSRQVLELOLWRIWKHXVHU SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2016 SAE International All rights reserved. No part of this publication may b

3、e reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-776-4970 (outside USA)

4、Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/standards.sae.org/ARP5448/7A AEROSPACE RECOMMENDED PRACTICE ARP5448/7 REV. A Issued 2002-07 Reaffirmed 2010-06 Revised 2016-12 Su

5、perseding ARP5448/7 Plain Bearing Wear Measurement RATIONALE Changes to this document are the result of a five year review, updating minor technical details and bringing formatting in accordance with current SAE standards. 1. SCOPE This standard details two methods of inspecting PTFE lined spherical

6、 or journal bearing wear outside the test apparatus. The methods described herein are applicable only to bearings which were unidirectionally loaded and the area of sliding wear is known and held constant throughout the dynamic test. The two methods described are: a. Destructive Inspection - Cut and

7、 measure (not applicable to molded liners) b. Nondestructive Inspection - Radial play (gauge) measurement 2. REFERENCES There are no referenced publications specified herein. 2.1 DEFINITIONS RADIAL PLAY: Refers to the total diametrical clearance in a bearing. The term radial refers to the direction

8、of gauge load and measurement axis. Radial play does not refer to taking only half the diametrical clearance nor measuring across the radius. 3. REQUIREMENTS NOTE: This method shall be useful only if the lined race of a spherical bearing or if the journal bearing were known to have remained stationa

9、ry during the dynamic test. This method shall be useful only for unidirectional loading. Load reversal during a wear test will require alternate techniques. 3.1 Destructive Inspection The scope of this test method shall be to measure the thickness of bearing liner remaining in the dynamic load zone

10、with respect to unworn liner at a position 180 degrees to the load zone. The required equipment shall be a metallurgical cut-off saw (preferred) or a hand hacksaw, micrometer calipers with a ball anvil adapter, and a razor blade knife. SAE INTERNATIONAL ARP5445/7A Page 2 of 6 3.1.1 Test Specimen Pre

11、paration Prior to measurement, misalign the ball and wipe clean to remove loose material. Repeat misalignment and wipe several times at different diameter locations. Compressed air may be used to flush out loose material, but care must be used to ensure that debris is not wedged into the bearing. 3.

12、1.2 Measurement Procedure a. Cut race at a location approximately 10 to 15 degrees with respect to the center of the load zone. When using a metallurgical cut-off saw the cut shall proceed through the race and ball component as shown in Figure 1. If a hand hacksaw is to be employed, cut the race thr

13、ough the same 10 to 15 degrees off load center and then at a location at 180 degrees about the race to make two equal race halves. b. Trim and scrape the liner material and adhesive from the race in the areas shown (TA and TB) in section A-A of Figure 1. When a spherical bearing race is being prepar

14、ed, only the centerline of the race where the metal is the thinnest requires complete cleaning to the metal substrate. Be careful not to remove any metal when scraping away the bonded adhesive. Journal bearings should be completely stripped across the full width so that wear may be evaluated on both

15、 edges as they often wear unevenly due to misalignment. c. Take at least three measurements of the metal substrate thickness in the equatorial area of a spherical or across the width of a journal bearing in the areas scraped clean of adhesive. Determine the minimum thickness and record measurements

16、(Regions TA and TB). d. Take at least three measurements of the liner and metal backing thickness in the center of the loaded area of a spherical race or at each end and center of a journal bearing (wear zone) to determine minimum thickness and record measurements (Regions TO and TF). e. Repeat oper

17、ation (c) approximately 180 degrees from the loaded area of the race or journal bearing to determine minimum thickness of the metal substrate and record measurements. This region is considered WKHXQORDGHGRQHand the liner is considered unworn in this area. f. Repeat operation (d) approximately 180 de

18、grees to the loaded are of the race or journal bearing to determine minimum liner plus substrate thickness and record. This region is considereGWKHXQORDGHGRQHDQGWKHOLQHULVconsidered unworn in this area. g. Subtract the “race only“ measurement that is adjacent to the center of the unloaded area from

19、the measurement of the liner and race thickness in the unloaded area of the race. Take at least three measurement readings. Use the minimum recorded value for each measurement. The difference is the thickness of the unworn section of liner material. h. Subtract the thickness of the worn section of l

20、iner from unworn section of liner, using the minimum recorded value of each measurement. The difference is the total wear of the liner system. SAE INTERNATIONAL ARP5445/7A Page 3 of 6 Figure 1 - Worksheet SAE INTERNATIONAL ARP5445/7A Page 4 of 6 3.2 Nondestructive Inspection The scope of this test m

21、ethod shall be to measure the radial play before and after a dynamic test to determine the increased radial play which shall be assumed to be liner wear. The required equipment shall be a radial play gauge per ARP5448/8 and a bore shaft or arbor if journal bearings are being tested. 3.2.1 Measuremen

22、t Procedure a. Place the test bearing in the radial play gauge per ARP5448/8. Ensure that the applied gauge loads are in accordance with the applicable specification. The radial play of the new bearing shall be recorded. The location of the measurement should be marked on the bearing permanently. Th

23、e marked position shall be the load zone during dynamic testing. The initial radial play shall be used as a baseline to compare the play after dynamic testing. This method may be used to measure journal bearing wear by placing a pin within the bore that is close to the bore size. The pin must be cla

24、mped and the journal bearing subject to the reversing load of the play tester. b. Remove the test bearing from the radial play gauge and perform dynamic testing as specified in the applicable specification. c. After dynamic testing verify that the race or journal bearing has not rotated within its h

25、ousing before removing it from the test machine. Misalign the ball of spherical bearings and wipe clean to remove loose wear debris. Repeat misalignment and wipe several times at different locations. Compressed dry air may be used to help flush out loose debris, but care must be used to ensure mater

26、ial is not wedged into the bearing. The inner lined surface of journal bearings must simply be wiped of loose debris. d. Place the test specimen into the radial play gauge as shown in Figure 2 so that the loaded area of the race and ball are in line with the radial play gauge loading. Measure and re

27、cord the radial play of the test specimen with the marked load zone in line with the reversing load of the play gauge. e. Determine the total wear of the liner system by subtracting the radial play before dynamic testing from the radial play after dynamic testing. 3.3 Test Parameters Test parameters

28、 shall include the following: a. Test specimen design envelope b. Dynamic test specification c. Test duration d. Failure criteria (maximum radial clearance) SAE INTERNATIONAL ARP5445/7A Page 5 of 6 Figure 2 3.3.1 Data Requirements Data requirements shall include the following as applicable: a. Thick

29、ness of lined race at load zone b. Thickness of metal race adjacent to load zone c. Thickness of lined race 180 degrees from load zone d. Thickness of metal race only, opposite load zone e. Unworn liner thickness f. Liner thickness at load zone g. Destructive total dynamic wear h. Gauge load SAE INT

30、ERNATIONAL ARP5445/7A Page 6 of 6 i. Pre-dynamic test radial play j. Post-dynamic test radial play k. Non-destructive total dynamic wear 3.3.2 Test Report The recorded data shall be summarized in report form and shall contain the following: a. Bearing description 1. Manufacturer and manufacturer par

31、t number 2. Lot number 3. A complete, dated drawing of the test bearing including dimensions and materials b. Test machine description c. Test parameters d. Raw data sheets for measurements and calculations 4. NOTES 4.1 Revision Indicator A change bar (I) located in the left margin is for the conven

32、ience of the user in locating areas where technical revisions, not editorial changes, have been made to the previous issue of this document. An (R) symbol to the left of the document title indicates a complete revision of the document, including technical revisions. Change bars and (R) are not used in original publications, nor in documents that contain editorial changes only. PREPARED BY SAE COMMITTEE ACBG, AIRFRAME CONTROL BEARINGS GROUP