1、 SURFACE VEHICLE RECOMMENDED PRACTICE Qualifying Aftermarket Two-Component Structural Foams J2621 REAF. JAN2011 Issued 2004-08 Reaffirmed 2011-01 Superseding J2621 AUG2004 1. Scope This recommended practice provides a guideline for qualifying automotive aftermarket, two-component structural foams, a
2、nd defines a classification system for such foams. 1.1 Purpose To establish a classification system for structural foams, and a method for testing them, thus allowing auto manufacturers and foam makers to specify the proper product for use in recommended repair procedures. 1.2 Background The need fo
3、r structural foams in the automotive collision repair market has grown as their use by the automotive OEMs in cars and trucks has grown. In recent years, structural foams have been used in new cars and trucks to help improve noise, vibration and harshness (NVH) characteristics, lower vehicle weight
4、and improve structural integrity. The proper performance of structural foams is especially critical during a collision, as they play an important role in collision energy management. Many aftermarket two-component structural foams are not implemented in the same manner as at the OEM level, nor are t
5、hey tested against rigorous OEM standards. This recommended practice provides OEMs with a method for specifying appropriate structural foams in their repair recommendations (see SAE J2376). There are several types of structural foams available in the OEM market. They can be characterized several way
6、s: the mode of cure, (i.e. heat cure or two-component ambient cure), by chemistry (epoxy or urethane) or by the strength of the final cured product. The critical factor in choosing the appropriate structural foam for aftermarket replacement is to match the original foam strength and cavity fill as c
7、losely as possible to that applied at the OEM. Structural foams are tested against rigorous standards for strength, corrosion resistance, and most importantly, vehicle performance, during the initial design stages at the OEM. SAE Technical Standards Board Rules provide that: “This report is publishe
8、d 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 the sole responsibility of the user.” SAE reviews each technical re
9、port at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. Copyright 2011 SAE International All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form o
10、r 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) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/w
11、ww.sae.org SAE values your input. To provide feedbackon this Technical Report, please visit http:/www.sae.org/technical/standards/J2621_201101 SAE J2621 Reaffirmed JAN2011 - 2 - OEM structural foams may be applied as a pumped-in mass that may be contained by baffles or blockers to maintain the foam
12、in a specific configuration. Structural foams may also be supplied as drop-in parts that contain an engineered carrier (metal or plastic) to which the structural foam is applied. These parts are then placed in the vehicle and cured during the bake process in the OEM paint shop. Repair of a body sect
13、ion in a manner that does not fill the cavity as specified by the OEM, or utilizes a structural foam that does not meet the original engineering requirements, can lead to a vehicle that no longer meets the original OEM performance objectives. 2. References 2.1 Applicable Publications The following p
14、ublications form a part of this specification to the extent specified herein.2.1.1 SAE PUBLICATIONSAvailable from SAE, 400 Commonwealth Dr., Warrendale, PA 15096-0001. The latest issue of SAE publications shall apply. SAE J369Cured Flammability SAE J1523Cure Rate SAE J1756Fogging Test SAE J2376New-V
15、ehicle Collision Repair Information 2.1.2 FORD MOTOR COMPANY SPECIFICATIONSAvailable from Ford Motor Company, 20000 Rotunda, Dearborn, MI 48121. Ford WSSM99P35AMaterial Specification Ford BV 11801Sag Resistance Ford BI 104-01Water Immersion Test Ford BQ 104-02Humidity Resistance Testing 2.1.3 GENERA
16、L MOTORS CORPORATION SPECIFICATIONSAvailable from Global Engineering Documents, 15 Inverness Way East, Englewood, CO 80112 GM N8297Structural Foam Performance Guidelines for Aftermarket Service Use 2.1.4 AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM) PUBLICATIONAvailable from ASTM, 100 Barr Harbo
17、r Drive, West Conshohocken, PA 19428-2959ASTM B 117Salt Spray Testing ASTM D 1621Compressive Strength ASTM D 3574 (Test A)Cured Density SAE J2621 Reaffirmed JAN2011 - 3 - 3. Definitions 3.1 Acoustic Foams Acoustic foams function either as a barrier to seal off a cavity to reduce wind noise, or as an
18、 absorption barrier for transmitted acoustical energy 3.2 Structural Foams Structural foams are typically rigid and much harder than acoustic foams. Structural foams depend on their stiffness or hardness to perform their required function of providing structural enhancement to auto body sections.3.3
19、 Drop-In Parts Drop-in parts are engineered parts in which a structural foam is applied to either a steel or plastic carrier, and then the carrier is inserted into the body cavity during the vehicle assembly process 3.4 Pumpable Structural Foams Pumpable structural foams are typically applied by pum
20、ping wet material into body cavities and allowing the material to cure in place.4. Structural Foam Characteristics The following items should be included in the labeling of aftermarket structural foams. 4.1 Type Classification system A classification system, based on compression strength modulus, is
21、 used to categorize structural foams (see Table 1). Both the OEM collision repair manual and the structural foam product label should state the type classification (see para. 7.1). TABLE 1STRUCTURAL FOAM TYPE CLASSIFICATION Type Modulus 25 CA 900 MPa B 701 900 MPa C 501 700 MPa D 301 500 MPa E 101 3
22、00 MPa 4.2 Bond Integrity The product label should state that the cohesive failure exceeds 90% and the corrosion undercut is less than 12 mm when the product is applied to the listed substrates (see para. 7.2). SAE J2621 Reaffirmed JAN2011 - 4 - 4.2.1 LISTED SUBSTRATESThe product label should list t
23、he substrates against which the bond integrity has been verified, such as hot-dipped galvanized steel, electro-galvanized steel, E-coated steel, and aluminum sheet of automotive quality.4.3 Cure Rate (SAE J1523) The product label should state the cure rate of the product. Most structural foams will
24、set up within 30 min and be fully cured in 24 h. 4.4 Cured density (ASTM D 3574/ ISO 845) The product label should state the interior density of the cured product as measured by Test A. 4.5 Volumetric Expansion The label should state the percent of volumetric expansion that occurs as the product cur
25、es (see para. 5.1.1).4.6 Mix Ratio The product label should clearly state the appropriate mix ratio of the components. 4.7 Sag Resistance (Ford BV 11801) Structural foams should have sufficient sag resistance to prevent excessive leakage and flow during application.4.8 Preconditioning Requirements T
26、he product label should state any preconditioning requirements, such as warming, to increase flow and reactivity. 4.9 Surface Preparation The label should describe any required preparation of the surfaces to which the product will be applied. 4.10 Cleanup Instructions The label should describe a met
27、hod of cleaning the product from adjacent surfaces, within 10 min of application, using a common cleaning solvent (such as naphtha), leaving no permanent stains. 4.11 Safety and Personal Protection Product labels should include warning statements regarding flammability (sparks and flames) and handli
28、ng precautions (skin and eye protection). SAE J2621 Reaffirmed JAN2011 - 5 - 5. Sample Preparation and Initial Measurements 5.1 Compression Test Sample Sets Five sets of five cylindrical samples shall be prepared. Each sample is made by pouring 500 cc of two-component structural foam into a vertical
29、 cardboard cylinder (75 mm inside diameter x 200 mm length). Immediately mark the height of the foam on the outside of the cylinder. Repeat until 25 cylinders have been filled and marked. Allow the samples to fully cure, following the manufacturers instructions.5.1.1 VOLUMETRIC EXPANSIONMeasure the
30、height of the cured samples and calculate the percentage change in volume for each sample. Record the average percentage change in volume for the 25 samples. Remove and discard the cardboard cylinders from the samples, and cut the samples to a length of 150 mm 0.1 mm. 5.1.2 PAINT BAKE SIMULATIONTo s
31、imulate a typical paint bake that would follow the repair of a vehicle, all test samples shall be baked for 30 min at 60 C.5.1.3 INITIAL TEST TEMPERATURESOne set of five samples shall be tested immediately following a five-hour soak at 30 C. Two of the remaining sets shall be similarly tested follow
32、ing soaks at 25 C and 80 C respectively (see para. 5.1.4). The remaining two sets shall be held in reserve for environmental exposure (para. 6) and later tests (para. 7.). 5.1.4 COMPRESSION STRENGTH MODULUS (ASTM D 1621COMPRESSIVE STRENGTH TESTING)Test three sets of samples at 10 mm/min compression
33、rate on an Instron or similar type of testing equipment to determine the initial strength modulus. Record the initial strength of the five samples in each temperature set. Disregard the highest and lowest readings in each set, and calculate the average of the middle three readings. Record the averag
34、e compression modulus for each temperature set, and select the lowest average modulus as the base for comparing the results of the measurements in para. 7.1. 5.2 Adhesion Test Sample Sets Two sets of five samples shall be prepared for testing the structural foam bond integrity. The samples are made
35、by forming 75 mm x 75 mm x 100 mm, open-top, rectangular adhesion cans. The walls and bottom of the cans are made of the substrates to be specified on the product label (see para. 4.2.1), and bonded together on the outside with heat-resistant aluminum tape. Pour 500 cc of two-component structural fo
36、am into each can and allow it to fully cure, following the manufacturers instructions. Subject both sets to the paint bake simulation in para. 5.1.2. Peel the cans from one set of the foam blocks and examine them for cohesive failure. All five of the adhesion cans should exhibit more than 90% cohesi
37、ve failure. Record the percentage of cohesive failure for each sample in the set. Reserve the remaining sample set for environmental exposure (para. 6) and later tests (para. 7.2). SAE J2621 Reaffirmed JAN2011 - 6 - 6. Environmental Exposure Requirement Environmental exposure should be conducted on
38、two sets of bare, cut compression cylinders and one set of adhesion cans, after the structural foam is cured and initial measurements have been taken (see para. 5.1.4 and 5.2). 6.1 Salt spray (ASTM B 117) 1000 hours 6.2 Humidity (Ford BQ 104-02) 30 days, 95% 5% Relative Humidity at 38 C.6.3 Water so
39、ak (Ford BI 104-01) Five days immersion in tap water at 25 C.7. Test Requirements After the environmental exposure of para. 6, all samples should be tested at 25 C.7.1 Compression Strength Modulus Following the environmental exposures in para. 6, perform the compression test of para. 5.1.4 on one sa
40、mple set. The structural foam must maintain more than 80% of its initial strength modulus, based on the average of the middle three readings, as recorded in para. 5.1.4. Record the average of the middle three readings, and use this average modulus to assign a type classification (see Table 1). Reser
41、ve the remaining sample set for testing in para. 7.3, 7.4 and 7.5. 7.2 Adhesion Test Following the environmental exposures in para. 6, the cans are peeled from the foam blocks and examined for percentage of cohesive failure. All of the adhesion cans should exhibit more than 90% cohesive failure, and
42、 no more than 12 mm corrosion undercutting at the material edge. Record the percentage of cohesive failure for each sample in the set.7.3 Dimensional Stability Measure and record the length of a compression test cylinder to 0.1 mm, and compare it to the original length (150 mm) measured in para. 5.1
43、.1. Record the percentage change in length. The maximum acceptable dimensional change is 5%. 7.4 Fogging (SAE J1756) Three hours at 100 C, 21 C cooling plate, posttest conditioning: 1 hour & 16 hours. The minimum acceptable fog number is 70. Formation of a clear film, droplets or crystals is cause f
44、or rejection. SAE J2621 Reaffirmed JAN2011 - 7 - 7.5 Cured Flammability (SAE J369/ ISO 3795) The maximum acceptable burn rate is 100 mm/min. 8. Notes 8.1 Key Words foam, structural foam, aftermarket, collision, damage repair, two-component PREPARED BY THE SAE STRUCTURAL FOAM COMMITTEEOF THE SAE MAIN
45、TENANCE DIVISION REAFFIRMED BY THE SAE COLLISION REPAIR COMMITTEE SAE J2621 Reaffirmed JAN2011 - 8 - RationaleSAE J2621 has been reaffirmed to comply with the SAE 5-Year Review policy. Relationship of SAE Standard to ISO Standard Not applicable ApplicationThis recommended practice provides a guideli
46、ne for qualifying automotive aftermarket, two-component structural foams, and defines a classification system for such foams. Reference Section SAE J369Cured Flammability SAE J1523Cure Rate SAE J1756Fogging Test SAE J2376New-Vehicle Collision Repair Information Ford WSS-M99P35-AMaterial Specificatio
47、n Ford BV 11801Sag Resistance Ford BI 104-01Water Immersion Test Ford BQ 104-02Humidity Resistance Testing GM N8297Structural Foam Performance Guidelines for Aftermarket Service Use ASTM B 117Salt Spray Testing ASTM D 1621Compressive Strength ASTM D 3574 (Test A)Cured DensityDeveloped by the SAE Structural Foam Committee Sponsored by the SAE Vehicle Service Development Division Reaffirmed by the SAE Collision Repair Committee
