1、T 809 om-11 SUGGESTED METHOD 1966 OFFICIAL STANDARD 1971 OFFICIAL TEST METHOD 1982 REVISED 1987 REVISED 1993 REVISED 1997 REVISED 1999 REVISED 2006 REVISED 2011 2011 TAPPI The information and data contained in this document were prepared by a technical committee of the Association. The committee and
2、 the Association assume no liability or responsibility in connection with the use of such information or data, including but not limited to any liability under patent, copyright, or trade secret laws. The user is responsible for determining that this document is the most recent edition published. Ap
3、proved by the Standard Specific Interest Group for this Test Method TAPPI CAUTION: This Test Method may include safety precautions which are believed to be appropriate at the time of publication of the method. The intent of these is to alert the user of the method to safety issues related to such us
4、e. The user is responsible for determining that the safety precautions are complete and are appropriate to their use of the method, and for ensuring that suitable safety practices have not changed since publication of the method. This method may require the use, disposal, or both, of chemicals which
5、 may present serious health hazards to humans. Procedures for the handling of such substances are set forth on Material Safety Data Sheets which must be developed by all manufacturers and importers of potentially hazardous chemicals and maintained by all distributors of potentially hazardous chemica
6、ls. Prior to the use of this method, the user must determine whether any of the chemicals to be used or disposed of are potentially hazardous and, if so, must follow strictly the procedures specified by both the manufacturer, as well as local, state, and federal authorities for safe use and disposal
7、 of these chemicals. Flat crush of corrugating medium (CMT test) 1. Scope This method describes a procedure for measuring the crushing resistance of a laboratory fluted strip of corrugating medium, and provides a means of estimating, in the laboratory, the potential flat crush resistance of a corrug
8、ated board. NOTE 1: While the choice of testing instrument does not create significant differences in this test, it should be noted that when the flat crush of the corrugated board is being determined, the rigid support instrument (T 825) gives significantly higher results than the flexible beam ins
9、trument (T 808). 2. Significance Rigidity of the fluted structure is one of the essential characteristics of corrugated board and flat crush resistance (T 825) is necessary to prevent crushing of the flute structure on the corrugator and other converting equipment. The corrugating medium test (CMT)
10、permits the evaluation of the crush resistance of corrugating medium before it is fabricated into combined board, and by consideration of the flat crush of the corrugated board produced may act as a basis for judgment of fabrication efficiency. 3. Apparatus1and materials 3.1 Medium fluter1, consisti
11、ng of a pair of matched “A”-flute type rolls thermostatically controlled to a temperature of 177 8C (350 15F). The dimensions of the fluting rolls are: 3.1.1 Roll face, 16.0 1.0 mm (0.63 0.04 in.). 1Names of suppliers of testing equipment and materials for this method may be found on the Test Equipm
12、ent Suppliers list in the set of TAPPI Test Methods, or may be available from the TAPPI Quality and Standards Department. T 830 om-11 Flat crush of corrugating medium (CMT test) / 2 23.1.2 Number of teeth, 84. 3.1.3 Depth of teeth, 4.75 0.05 mm (0.2 0.002 in.). 3.1.4 Roll diameter tip to tip, 228.5
13、0.5 mm (9 0.02 in.). 3.1.5 Radius of teeth at peak, 1.5 0.1 mm (0.06 0.004 in.). 3.1.6 Radius of teeth at base, 2.0 0.1 mm (0.08 0.004 in.). 3.1.7 The force between the rolls is set at 100 10 N (22.5 2.25 lbf.). 3.1.8 The speed of the fluting rolls is permanently set at 4.5 r/min 1.0 r/min. 3.2 Rack
14、 and comb, (see figure 1) having the following characteristics: Fig. 1. Drawing of rack and comb. 3.2.1 Rack, 11 teeth, 10 valleys. 3.2.1.1 Height of teeth, 4.75 0.05 mm (0.2 0.002 in.). 3.2.1.2 Tooth spacing is 8.50 0.05 mm (0. 335 0.002 in.). 3.2.1.3 Width, 19.00 - 0.0 mm (0.75 0.0 in.). 3.2.2 Com
15、b, number of prongs, 10. 3.2.2.1 Prong length, at least 19 mm (0.75 in.) wide. 3.2.2.2 Max. prong thickness, 3.4 0.1 mm (0.13 0.004 in.). 3.3 Pressure sensitive tape, at least 15 mm (0.6 in.) width. While no standard tape can be specified in this method at this time, some laboratories report an impa
16、ct of the tape used on test results. 3.4 Specimen cutter, a hand lever operated diecutter. The female portion is 12.7 0.1 mm (0.5 0.004 in.) 150 to 160 mm (6 to 6.3 in.). The male die is machined to fit the female. The cutting assembly is provided with a specimen delivery slot. The whole is enclosed
17、 in a frame to keep out dust. 3.5 Flexible beam compression or rigid-platen testing machine, in accordance with TAPPI T 811 “Edgewise Compressive Strength of Corrugated Fiberboard (Short Column Test).” 3.5.1 The surface of the platens shall be provided with some means to prevent slippage of the test
18、 piece during compression, for example, by means of a matt finish or being faced with crocus cloth or its equivalent, adhered free of ridges and maintaining parallel surfaces. 4. Test specimens From each test unit accurately cut at least 10 specimens. Cut the test specimens 12.7 0.1 mm (0.5 0.004 in
19、.) 150 to 160 mm (6 to 6.3 in.) on the die cutter. Assure that the longer dimension is in the machine direction of the medium. 5. Conditioning Condition the specimen strips prior to testing in an atmosphere in accordance with TAPPI T 402 “Standard Conditioning and Testing Atmospheres for Paper, Boar
20、d, Pulp Handsheets and Related Products.” 3 / Flat crush of corrugating medium (CMT test) T 809 om-11 6. Procedure 6.1 Arrange all equipment and supplies to facilitate completing operations in the specified time (see 10.3). 6.2 Perform the fluting operation only after the specimens have reached equi
21、librium with the specified atmosphere. Heat the fluting rolls to 177 8C (350 15F) as shown by the temperature indicator. 6.2.1 Feed the specimen into the guide slot of the fluter, so that the bottom edge of the specimen rides flat on the hot plate. 6.2.2 Place the fluted specimen, which emerges on t
22、he other side, on the corrugated rack, so that a portion of the specimen is resting on the flat surface at each end of the rack. Place the comb over the fluted specimen, so that it is held firmly into the flutes of the rack, making certain that the specimen is bottomed uniformly in each of the flute
23、s. Exercise care in handling the comb to avoid dropping it. A rolling motion of the comb as it is placed on the specimen aids in forming the specimen onto the rack. 6.2.3 Holding the specimen firmly in the rack, place a 130 mm (5 in.) strip of at least 15 mm (0.59 in.) wide pressure sensitive tape,
24、adhesive side down, on the exposed flute tips and stroke down firmly. If more than 10 flutes are formed, crush the extra flute(s). Carefully, slip the comb out of the flutes without damage to the specimen. Then, lift the resulting 10-flute strip straight up from the rack by the edges of the tape to
25、avoid damaging the flutes. 6.3 Place the specimen on the lower platen of the compression tester, flutes facing up. Apply compressive force to the specimen, recording the peak load. 6.3.1 The rate of platen movement required for a flexible beam compression machine has been determined to be 111 22 N/s
26、 (25 5 lbf/s). The rate of platen movement for a rigid support compression machine should be set to 12.500.25 (0.500.01) mm per minute. Record the platen movement rate actually used. 6.3.2 The function of the matt or crocus cloth surface on the platen is to prevent leaning failures due to slippage o
27、f the specimen. 6.4 Perform all of these operations using the same technique and speed for each specimen. Test the specimen immediately after fluting so that the time from complete emergence of the specimen from the fluter to the initial application of the crushing force is 5-8 s. NOTE 2: Failure to
28、 maintain the 5-8 s range may result in low or erratic results. See also 10.2. 7. Report Include the following in the report: (1) the average medium flat crush N(CMT) value of 10 determinations, to the nearest 5 N (1 lbf); (2) the standard deviation of N(CMT) values; (3) the type of compression test
29、er used. 8. Precision 8.1 For the flexible beam instrument: These data were obtained in a round robin among 29 laboratories, using flexible beam type compression testers 8.1.1 Repeatability (within a laboratory) = 4.5%, 10 specimens/average. 8.1.2 Reproducibility (between laboratories) = 10.0%, 10 s
30、pecimens/average. 8.2 For the rigid platen instrument. The following estimates of repeatability and reproducibility are based on results from the CTS Containerboard Interlaboratory Program. The data was drawn from flat crush results from 53 laboratories for two different samples of 26 lb. corrugatin
31、g medium. The testing was conducted in both 2002 and 2005. Only participants who reported using rigid-platen type instruments and adhering to TAPPI conditioning requirements were included in the calculation of the precision estimates. 8.2.1. Repeatability (within a laboratory) = 5 %, 10 specimens/av
32、erage 8.2.2 Reproducibility (between laboratories) = 11 %, 10 specimens/average The precision estimates are based on one test result per lab, per material Repeatability and reproducibility are estimates of the maximum difference, (at 95%) which should be expected when comparing test results for mate
33、rials similar to those described above under similar test conditions, in accordance with the definitions of these terms in TAPPI T 1200 “Interlaboratory Evaluation of Test Methods to Determine TAPPI Repeatability and Reproducibility.” These estimates may not be valid for different materials or testi
34、ng conditions 9. Keywords Corrugating medium, Flat crush tests, Corrugated boards, Compressibility, Compression strength T 830 om-11 Flat crush of corrugating medium (CMT test) / 4 410. Additional information 10.1 Effective date of issue: May 1, 2011. 10.2 Another procedure has received wide use. Af
35、ter lifting the composite test piece from the rack, let it condition in the testing atmosphere for 32.5 2.5 min (30 to 35 min) before placing on the lower platen of the compression apparatus, and test it for its flat crush resistance according to the procedure in 6.2. The precision of this procedure
36、 is unknown. 10.3 For most reliable results, the time for specimen preparation must be maintained within the 5-8 s time limit specified. This is the time interval from the discharge of the fluted specimen from the fluter to the initial application of force in the compression tester. To readily achie
37、ve this, the following suggestions have been found convenient: 10.3.1 The compression tester should be equipped with an automatic stop or limit switch to control the initial clearance between the platens to a minimum, convenient for insertion of the specimen. 10.3.2 Mount the test equipment on the l
38、aboratory bench top, so that it is in a convenient position. For a right handed tester this would be: left to right facing the equipment, fluter, comb and rack, and compression tester with approximately 250 mm (10 in.) spacing between units. 10.3.3 Precut tape strips to proper length and adhere one
39、end lightly to edge of bench. 10.3.4 Insert medium specimen into fluter with left hand. 10.3.5 Pick up comb with left hand. 10.3.6 Remove fluted specimen from fluter with right hand and place specimen on rack. 10.3.7 Holding comb in left hand, securely position fluted medium in rack. 10.3.8 Apply ta
40、pe with right hand, using thumb to crush additional flutes at each end of the 10 flute test strip. 10.3.9 Remove comb carefully from taped specimen with left hand, holding specimen in reach with right hand. 10.3.10 Use right hand to insert specimen into compression tester plates. NOTE 3: For a left
41、handed tester much of the above procedure would be reversed. 10.3.11 Start compression tester with left hand on switch, or use foot pedal if unit is so equipped. 10.3.12 Return compression tester platens to initial position at completion of test. 10.4 Related methods: ISO 7263-1994 (E) describes two
42、 procedures: immediate testing (15 3 s after commencement of fluting), or 30 min reconditioning of fluted sample moisture content prior to compression test. 10.5 Revisions 10.5.1 2011 revisions included restructuring the procedure section to better fit the decimal system of paragraph numbering; clar
43、ifying the compression process itself; and adding a comment to 3.3 relative to the impact of tape choice on results. Appendix A: Calibration of the medium fluter A.1 Fluting rolls (Horizontal roll type). Uniform meshing of fluting rolls can be checked by the use of National Cash Register Tape - CB w
44、hite NCR paper and CR green tinted NC paper C2R. A 12.7-mm (0.5-in.)-wide strip of each type of paper is run through the fluting rolls. The pressure pattern will appear on the green tinted strip. The pressure lines should be uniform and extend the full 12.7 mm (0.5-in.) width of the strip. If there
45、is more impression at the top or bottom of the rolls, they are not in the same plane. This means that the heating plate has warped, is worn unevenly, or the bearings are worn. In any case, the fluter should go back to the manufacturer for repair. A.1.1 The rolls should ride flat on the heating plate
46、. If the drive roll is not flat on the heating plate, loosen the collar directly above the bottom bearing housing and tap the roll lightly until it is lying flat. It may be necessary to loosen the bottom bearing also. Make this adjustment only when the fluter is up to normal operating temperature. W
47、hen the roll is flat, tighten all bolts and set screws. Remove driven roll by taking out the center bolt and lifting the roll up by bolts inserted in the thread holes provided. Inspect the heating plate for wear of chrome plating. If worn, a new heating plate should be installed by the manufacturer.
48、 The roll can also be inspected for smoothness and wear on the bottom. The spring-loaded post slide can be checked for freeness of movement and lubricated with powdered graphite, if necessary. When the roll is replaced, powdered graphite should be added to the lubricating hole while the roll is turn
49、ing. Graphite should be added until the grooves under the roll are completely filled. The same holds true for the drive roll. A.2 Spring force. The bar at the front end of the heating plate (on older model fluters) which holds the spring in place can be removed and the spring taken out. By placing the spring upright in the compression tester and applying force until the gage reads 100 N (22.5 lbf), the length of the spring at that point can be determined. A.2.1 The distance from the edge of the
