FORD FLTM BO 121-01-2015 DETERMINATION OF SEAT FOAM PROPERTIES IN COMPRESSION.pdf

1、 FORD LABORATORY TEST METHOD BO 121-01 Date Action Revisions Rev. 0 2015 12 09 Activated B. Witkowski, NA Controlled document at www.MATS Copyright 2015, Ford Global Technologies, LLC Page 1 of 6 DETERMINATION OF SEAT FOAM PROPERTIES IN COMPRESSION Application The purpose of this test method is to d

2、efine the steps required to obtain the initial thickness and to measure the hardness and hysteresis loss of molded flexible PUR foam padding material used for automotive seat cushions, seat backs, and other flexible foam applications. Refer to Appendix A for a summary of Load Test Fixture (LTF) desi

3、gn guidelines and Appendix B for a detailed summary in table form of the test method. Apparatus and Materials Required Universal Test Machine The typical equipment used for measuring foam pad hardness and hysteresis is a Zwick Materials Testing Z010 machine. Other manufacturers may be used provided

4、the equipment has the capability of measuring the force of the load and unload curve to a precision of 1% or 1N whichever is greater. In addition, the equipment must be able to provide a means of measuring the test piece thickness under load to an accuracy of 0.5mm. The support surface of the test m

5、achine shall be rigid and horizontal in nature, providing a perpendicular condition between the part and the load application. The support surface of the test machine shall be suitably vented with holes 6.0 0.1mm in diameter and 20.0 0.1mm pitch. The load cell rating and tolerance should be included

6、 as a note when reporting values for this method (i.e. 5kN load cell, 0.5% accuracy). The equipment used for the test must have the ability to establish individual preloads, initial thickness values, and test speeds for the conditioning and test cycles. In addition, the equipment must be able to out

7、put stress/strain curves, hysteresis loss, and any given load value on either the load or unload curve. Indenter Platen The indenter platen used for this test is a 200 1 mm diameter flat circular plate with an edge radius of 1.0 mm. A 360 degree ball/universal joint with a central axis located 22 2.

8、5 mm from the contact surface of the indenter platen is used throughout the test protocol. The ball joint must be free to move through all aspects of the test protocol when a downward force 4.0N is applied to the outer edge of the indenter platen. A representative indenter platen is pictured in Figu

9、res 1 3 and typical dimensions are provided in Figure 4. On the rare occasion that the size and or shape of the test specimen does not lend itself to be tested with the standard size platen, it is permissible to select other suitable size and shaped indenters. The selected indenter must be specified

10、 on the engineering drawing and agreed to by all concerned parties. Figure 1 Figure 2 FORD LABORATORY TEST METHOD BO 121-01 Copyright 2015, Ford Global Technologies, LLC Page 2of 6 Figure 3 Figure 4 Load Test Fixture Support A foam test sample shall always be supported by means of a test fixture as

11、per the engineering drawing. The load test fixture support surface contours shall mimic the “B” surface of foam sample being tested. The test fixture drawing should detail fixture alignment to insure the load application is perpendicular to the “A” surface of the test sample. Use of a round or recta

12、ngular test fixture is acceptable to accommodate planar “B” surfaces, provided the test fixture presents a support surface equal to, or larger than the diameter of the indenter platen. Perforation of the test fixture is optional. Further details of Load Test Fixture may be provided by customer speci

13、fication. Test fixture details described in the Load Test Fixture Design Guidelines in Appendix A. Use of a circular weighted ring to insure B-surface fit to test fixture is permitted. Ring is to be constructed with a minimum internal diameter of 245 mm and a maximum outside diameter of 300 mm. Tota

14、l mass of the ring must be 1.8 0.2 kg. Thickness and material type used for ring construction is at the discretion of the supplier. Non slip material may be added to the ring to prevent movement during pre-conditioning and test cycle. Refer to Figure 5 for application detail. Figure 5 Laboratory Con

15、ditions All test values indicated herein are based on material conditioned and tested in a controlled atmosphere of 23 2 C and 50+/- 5% relative humidity, for not less than 4 hours prior to testing, unless otherwise specified. Molded foam test samples or parts must be allowed to cure a minimum of 18

16、 hours from time of molding prior to performing hardness and hysteresis loss testing for prototype or production control purposes. FORD LABORATORY TEST METHOD BO 121-01 Copyright 2015, Ford Global Technologies, LLC Page 3of 6 Specimen Size and Preparation The specimen size must possess a minimum sur

17、face area of 40,000 mm2 to allow the indenter to be applied to the test surface of the foam without risk of misaligning the centerline of the load application to the sample. Foam product that can be tested using this method are test coupons (200L x 200W mm minimum), seat cushions, seat backs, or any

18、 foam articles which comply with the indenter foot size. Please note, all test samples are required to be crushed thoroughly after molding in accordance with manufacturing process. Front and rear seat cushion and back pads or related articles are required to be template checked prior to any testing.

19、 Once its determined they meet design surface requirements, testing can precede. On the rare occasion that the size and or shape of the test specimen did not lend itself to be tested with the standard size platen, alternate sample size should be agreed upon on Engineering Drawing. TEST PROCEDURE Tes

20、t Fixture Height Zeroing Process Align the test fixture to its proper location on the machine test surface to center the load application. Determine the test fixture height by contacting a minimum of two points of the indenter platen to the load test fixture, without the foam pad present (see Figure

21、s 6 and 7 for reference). Begin the fixture zeroing process from an arbitrary point above the surface of the load test fixture and carefully move the indenter platen, at a safe crosshead speed, downwards towards the fixture until the indenter plate is within close proximity to the fixture surface. C

22、ontinue to proceed towards the support surface at a crosshead rate of 3 2 mm/minute until a force of 15 5 N is applied to the load cell. This typically accomplished via an automatic function included in the test software. When this force is reached the height of the test fixture is established. Figu

23、re 6 Figure 7 Initial Thickness Place the foam test specimen on the load test fixture. Raise the crosshead such that the indenter platen is at an arbitrary point above the “A” surface of the foam test sample. Lower the crosshead and indenter platen at a speed of 50 mm/minute toward the foam surface

24、until force 4.5 N is applied to the load cell. At this point, the machine records the initial thickness of the foam pad and test block composite. Calculation is performed to determine the initial thickness of the foam pad test sample by subtracting the height established for the load test fixture fr

25、om the composite height of the load test fixture and the foam pad. Immediately following the determination of the initial thickness, zero the displacement on the load cell and proceed. Conditioning Cycles Starting from an arbitrary point above the foam surface, proceed to lower the crosshead at a ra

26、te of 100 mm/minute such that the indenter platen contacts and conditions the foam sample two times to a depth of 70% based on the initial thickness. This step is performed without a rest interval between the cycles. FORD LABORATORY TEST METHOD BO 121-01 Copyright 2015, Ford Global Technologies, LLC

27、 Page 4of 6 Test Cycle Immediately after the conditioning cycles are complete, the indenter platen is raised above the foam surface until a point of -5 mm strain. Immediately after this point is realized, the indenter platen proceeds towards the “A” surface at rate of 50mm/minute and apply a force o

28、f 4.5 N to the foam test sample using the indenter platen. Establish a new initial thickness in the test cycle by zeroing the displacement and force then immediately begin the test cycle. The test loads the foam at a speed of 100mm/minute to a depth of 70% and records the load curve based upon the i

29、nitial thickness. After reaching 70% compression, the machine immediately unloads the foam (zero dwell) at the same rate to the point of zero load and records the unload curve. Hardness- Determination Record the force obtained during the test cycle in Newtons (N). The force values are taken instanta

30、neously from the load curve during the test cycle (reference section 5.4). Report the values obtained at deflections of 25%, 50%, and 65% of the initial thickness value determined during the test cycle. A) The force measurement obtained at 25% compression is referred to as the 25% ILD hardness value

31、 B) The force measurement obtained at 50% compression is referred to as the 50% ILD hardness value C) The force measurement obtained at 65% compression is referred to as the 65% ILD hardness value D) Support Factor = 65% Force (N) / 25% Force (N) Refer to Appendix C for a summary of required outputs

32、 from the test. Hysteresis- Determination Using the data obtained during the test cycle, the test equipments software must be able to provide the hysteresis loss of the foam test sample. The software must be able to calculate the differential in area beneath the load and unload curves and report the

33、 area differential as a percentage of the total area underneath the load curve. The following explanation is for verification only. The loaded area is determined by integrating the line measured during the compression cycle of the test between the point at 0% compression - 0 load and the point at 70

34、% compression. The unloaded area is determined by the integration of the line formed during the return path between the same points. Hysteresis loss %= (Loaded Area Unloaded Area) / (Loaded Area) X 100 Comfort Index (C.I.) Determination An additional parameter, referred to as the Comfort Index (C.I.

35、), which is the ratio of the 65% force to the 25% force should also be reported. Comfort Index (C.I.) = 65% Force (N) / 25% Force (N) FORD LABORATORY TEST METHOD BO 121-01 Copyright 2015, Ford Global Technologies, LLC Page 5of 6 Appendix A Load Test Fixture (LTF) Design Guidelines The load test fixt

36、ure shall be manufactured of a stable material that does not deflect under testing parameters. The LTF shall conform to the B-surface of the pad and provide positive registration in the X,Y and Z directions All vertical surfaces shall have a 2 mm clearance for ease of pad installation and removal Th

37、e resulting A-surface of the pad on the LTF shall be parallel to the indenter platen with a 5 degree tolerance defined in the IFD testing zone Long pads shall be supported to avoid cantilevering of the pad The pad shall not touch the support surface of the test machine The LTF shall be positively al

38、igned to the support surface of the test machine at all test locations to insure the indenter platen coincides with the IFD compression area alignment features identified on the part. If pad is dual hardness, the LTF must be designed to provide support to the foam pad in the direction of load applic

39、ation in all test locations LTF should be identified with the part number, ECN/date, supplier name Shall be CNC cut to Math data Appendix B Foam Hardness Measurement - Machine Setup Parameters Insert Area Foam Hardness Measurement Item# Testing Parameter Test Requirement 1 Indenter (Platen) Size: mm

40、 200 + 1 (or as agreed upon with customer) 2 Test Fixture Height Determination Pre-Load Speed (mm/minute) 3 + 2 3 Test Fixture Height Determination Pre-Load (N) 15 + 5 4 Test Fixture Contact Points with Indenter Platen (universal joint active) 2 minimum 5 Conditioning Cycle Pre-Load Speed (mm/minute

41、) 50 + 1 6 Conditioning Cycle Pre-Load (N) 4.5 + 0.5 7 Zero the displacement of the Conditioning Cycle Pre-Load (yes/no) Yes 8 Conditioning Cycle Speed (mm/minute) 100 + 1 9 Conditioning Cycles 2 10 Conditioning Cycle Deflection (%) 70 + 1 11 Conditioning Cycle Load Removal (mm) -5.0 + 1 12 Recovery

42、 after Conditioning Cycle (Minutes) 0 13 Test Cycle Pre-load Speed (mm/minute) 50 + 1 14 Test Cycle Preload (N) 4.5 + 0.5 15 Zero the Test Cycle Pre-Load and Displacement (yes/no) Yes 16 Test Cycle Speed (mm/minute) 100 + 1 17 Test Cycle Deflection (%) 70 + 1 18 Test Cycle Dwell Time at Test Point(s

43、) (Seconds) 0 19 Test Cycle Unload Speed (mm/minute) 100 + 1 20 Point of Test Cycle End (N) 0.0 FORD LABORATORY TEST METHOD BO 121-01 Copyright 2015, Ford Global Technologies, LLC Page 6of 6 Appendix C Test Output Insert Area Foam Hardness Measurement Item# Required Test Cycle Output 1 25 % IFD, 50% IFD, 65% IFD (N) 2 Hysteresis Loss (%) 3 Support Factor (unit-less) 4 Test Cycle Initial Thickness (mm) 5 Lab Humidity at Time of Test (%) 6 Lab Temperature at Time of Test (C)