1、 SAE Technical Standards Board Rules provide that: “This 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 there
2、from, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. Copyright 2006 SAE International All rights reserved. No part of this publication m
3、ay be 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: 724-776-4970 (outside USA)
4、 Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org J2724 ISSUED JUN2006 SURFACE VEHICLE RECOMMENDED PRACTICE Issued 2006-06 Measurement of Disc Brake Friction Material Underlayer Distribution RATIONALE Not applicable. 1. SCOPE This procedure describes a method for me
5、asuring the fraction of underlayer (also referred to as backing layer) existing at any given height above the a disc brake friction materials shoe plate. Measuring underlayer distribution is useful for computing useable lining thickness and for friction material quality management. 2. REFERENCES The
6、re are no referenced publications specified herein. 3. INSTRUMENTATION A friction material thickness grinder, a micrometer, and a transparency with a 10 mm grid are required to run this test. A digital camera with image analysis software is a preferred but optional method. All test measurement equip
7、ment must be calibrated and maintained per local standards. All applicable safety guidelines and procedures must be followed. Dust collectors should be used when grinding the friction material. 4. SAMPLE PREPARATION This test can be run on new or used disc brake pads with visually distinguishable ba
8、cking layers. 5. OPERATION 5.1 Visually check the lining for any defects such as: cracks, delaminations, edge lift, un-bonded insulators, or foreign contamination. Record any defects or the absence of defects in the test report. 5.2 Grind the lining to the specified thickness (see Section 6) and mea
9、sure that thickness. The measured pad thickness must be within +/-0.1 mm of target thickness. 5.3 At each thickness specified, overlay a transparent film with 10 mm grid lines. Using the grid, count the number of squares with 50% or more backing layer and the number of squares with 50% or more frict
10、ion material. Add these two numbers together and divide to calculate the ratio (percent) of backing layer and friction material. Alternatively, you may photograph the lining (see Figure 1) and use appropriate image analysis software to compute the percentage of underlayer and friction materials. Cop
11、yright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J2724 Issued JUN2006 - 2 - 65% lining (35% Backing Material) No Pad Defects Found FIGURE 1 - PAD GROUND TO 2 mm ABOVE BACKING PLATE 5.4 Repeat section
12、s 5.2 and 5.3 at any other specified lining thicknesses (see Section 6). 6. GENERAL INSTRUCTIONS In development, the backing layer thickness is typically assessed at 3, 2.5, 2, 1.5 and 1 mm above the shoeplate. In production the test only needs to be run to evaluate the conditions specified (e.g. 90
13、 minimum friction material when the pad is ground to 1.8 mm over the shoeplate). 7. PRESENTATION OF DATA Summarize the readings and include any photographs in a table. PREPARED BY THE SAE BRAKE LININGS STANDARDS COMMITTEE Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
