1、TAPPI/ANSI T 825 om-14 PROVISIONAL METHOD 1986 OFFICIAL METHOD 1996 REVISED 2003 REVISED 2009 REVISED 2014 2009 TAPPI The information and data contained in this document were prepared by a technical committee of the Association. The committee and the Association assume no liability or responsibility
2、 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. Approved by the Standard Specific Interest Group for thi
3、s 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 use. The user is responsible for determining that the sa
4、fety 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 may present serious health hazards to humans. Procedu
5、res 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 chemicals. Prior to the use of this method, the user must det
6、ermine 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 of these chemicals. Flat crush test of corrugated boa
7、rd (rigid support method) 1. Scope The flat crush test (1) is a measure of the resistance of the flutes in corrugated board to a crushing force applied perpendicular to the surface of the board under prescribed conditions. The test is satisfactory for single-faced or single wall (double-faced) corru
8、gated board, but not for double-wall or triple-wall corrugated board, because of lateral motion of the central facing or facings. In this method the specimen rests on an essentially rigid support and is tested at a constant deflection rate. See TAPPI T 808 “Flat Crush Test of Corrugated Board” for t
9、he procedure in which the specimen rests on a flexing support and is tested at a constant rate of loading. The test methods do not produce similar results. 2. Significance 2.1 Flat crush is a measure of the flute rigidity of corrugated board. A high flat crush value indicates a combination of good f
10、lute formation and adequate medium strength. Low flat crush can indicate a number of conditions including low medium strength, leaning flutes, and/or crushed flutes. The primary interest of the test is to determine if the mediums contribution to combined board rigidity has been compromised. 3. Appar
11、atus 3.1 Compression tester having the following: 3.1.1 A rigidly supported platen and a driven platen, each having a working area of approximately 100 cm2(about 15.5 in.2). The platens are required to have not more than 0.050 mm (0.002 in.) lateral movement and the rigidly supported platen not more
12、 than 0.150 mm (0.006 in.) movement, perpendicular to the surface, within a load range of 0 to 4500 N (0 to 1000 lbf). Within a 100 cm2(15.5 in 2) working area each platen shall be flat within 0.0125 mm (0.0005 in.) and the platens shall remain parallel with each other within 1 part in 2000, or 50 m
13、/100 mm (0.0005 in./in.) throughout T 825 om-14 Flat crush test of corrugated board (rigid support method) / 2 the test. After the platens are checked for parallelism, they may be faced with crocus or emery cloth, free of ridges, by means of double sided tape to prevent slippage. These facings shall
14、 be changed after every 2000 tests. 3.1.2 A means for moving the driven platen to achieve an initial platen separation of at least 60 mm (2.36 in.). Within a range of platen separation of 0 to 60 mm (0 to 2.36 in.) and within a load range of 0 to 4500 N (0 to 1000 lbf), the speed of the driven plate
15、n shall be controllable at 12.5 0.25 mm (0.50 0.01 in.) per minute. For convenience, the test machine should be capable of rapid return and automatic, settable positioning. 3.1.3 A capacity of at least 4500 N (1000 lbf). 3.1.4 A means for measuring and indicating the maximum load sustained by the te
16、st specimen within 2.2 N (0.5 lbf). 3.1.5 An indicating mechanism that can be checked accurately with dead weight load, load cell, or proving ring. The accuracy required is 0.5% or 2.2 N (0.5 lbf), whichever is greater. 3.2 Specimen cutter, consisting of a device capable of cutting through the corru
17、gated combined board structure without crushing areas at the cut edges. This may be circular, square, or rectangular. 4. Sampling and test specimens 4.1 From each test unit of a sample obtained in accordance with TAPPI T 400 “Sampling and Accepting a Single Lot of Paper, Paperboard, Containerboard,
18、or Related Product,” select a minimum of 10 specimens free of abnormalities not representative of the combined board. Cut, preferably in circular form, so that each is either 32.3 cm2(5.00 in.2), 50.0 cm2, (7.75 in.2), or 64.5 cm2(10.00 in.2) in area, at least 38 mm (1.5 in.) away from printed matte
19、r, scores, and diecuts. 4.1.1 If the specimens are not circular, exercise special care to maintain the desired area accurately. 4.2 Avoid crushing areas at the cut edges, and, where possible, avoid fractional flute counts. 5. Safety precautions 5.1 The circular cutter used to prepare the samples has
20、 sharp blades and is often unguarded or improperly guarded. Proper Personal Protection Equipment (PPE) (cut-proof gloves) should be worn at any time one is working around the blades. A warning label should be on each cutter advising of the proper PPE. The motorized cutter blade is moving whenever th
21、e unit is powered. Any time the hands reach under to retrieve a sample they are exposed to the blade. The hand driven cutter uses sharp pointed spikes to puncture the board and hold it steady while being cut. These holding spikes, along with the blades, can cause severe injury. 5.2 Care should be ta
22、ken when changing the flat crush cutter blades. The blades are thin and must be bent around the holder as they are secured. A blade can fracture during this process and send off shards. It is recommended that safety glasses be worn as well as cut-proof gloves during this operation. 6. Procedure 6.1
23、Precondition, condition and test the board in an atmosphere in accordance with TAPPI T 402 “Standard Conditioning and Testing Atmospheres for Paper, Board, Pulp Handsheets, and Related Products.” 6.1.1. Position each specimen centrally on the lower platen. Apply the crushing load to the specimen unt
24、il the side walls of the corrugations collapse completely. Failure is defined as the maximum load sustained before complete collapse. NOTE 1: Normally, a preliminary end point occurs when the tips of the corrugation flatten on one or both sides of the specimen. This should not be confused with the f
25、inal end point when the corrugations collapse completely. The threshold setting on the compression tester may be set to a level above the preliminary end point so the machine does not look for failure until after that point. If the collapse of the corrugations is so gradual that no such peak load is
26、 distinctly registered, note this fact. In this case, adjusting the yield deflection percentage (sensitivity) down may alleviate the problem. If not, watch each test to determine the peak load. Maximum crush load is often near total collapse of the flutes. A strip chart recorder connected to the loa
27、d cell output will aid in the determination of the correct endpoint of the test. Some machines have the ability to record the loads seen over a specific travel distance and report the maximum load. 3 / Flat crush test of corrugated board (rigid support method) T 825 om-14 7. Report 7.1 Report the fl
28、at crush test results, in kilopascals (kPa) or pounds force per square in., (psi) as the average of ten determinations, to three significant figures (1 psi = 6.895 kPa). 7.1.1 To get the flat crush value in kPa (psi), divide the maximum force by the area of the sample. 7.2 Include for a complete rep
29、ort: 7.2.1 The standard deviation. 7.2.2 The total number of specimens tested. 7.2.3 The number of specimens exhibiting rolling failure which is an irregular skewed pattern or leaning type of collapse of the flutes. 7.2.4 The model and type of testing machine used. 7.2.5 Indicate the flute size and
30、type. Flute counts can vary significantly for a given contour. 8. Precision 8.1 The following estimates of precision are based on an interlaboratory study with three grades of combined board that had flat crush strengths ranging between 207 kPa (30 psi) and 276 kPa (40 psi), which were tested using
31、replicates in 7 different laboratories. Repeatability (within a laboratory) = 38 kPa (5.5 psi). Reproducibility (between laboratories) = 66 kPa (9.6 psi). NOTE 2: CTS determined in 1995 and reaffirmed in 2003 that there was no convincing evidence that variation in this test increases with increasing
32、 strength of the material being tested, so the expression of the variation is best described by a fixed unit and not by a percentage. 8.2 Repeatability and reproducibility are estimates of the maximum difference that should be expected when comparing replicate measurements for materials similar to t
33、hose used in round robin of testing. 8.3 Round robin testing was performed on three samples of C-fluted board with the following liner and medium combinations: A. 52-26-52 B. 42-33-42 C. 42-26-33 The summary of the data collected and analyzed by Collaborative Testing Services has been placed on file
34、 at TAPPI. 9. Keywords Flat crush tests, Corrugated board, Compression tests 10. Additional information 10.1 Effective date of issue: to be assigned. 10.2 TAPPI T 808 which uses a deflecting beam tester is linked statistically to the Concora test T 809 “Flat crush of corrugating medium (CMT test)”,
35、but shows lower values when compared to TAPPI T 825 on the same sample. 10.3 Related methods: APPITA P 429 “Flat Crush Resistance of Corrugated Board,” Technical Association of the Australian and New Zealand Pulp and Paper Industry, Parkville, Australia; PAPTAC D.20 “Flat Crush Test of Corrugated Bo
36、ard,” Canadian Pulp and Paper Association, Montreal, Canada; ISO 3035 “Determination of Flat Crush Resistance “ Single-Faced and Single-Wall Corrugated Fiberboard,” International Organization for Standardization, Geneva, Switzerland; SCAN P-32 “Flat Crush Resistance of Corrugated Fiberboard,” Scandi
37、navian Pulp, Paper, and Board Testing Committee, Stockholm, Sweden. 10.4 Revision history: 10.4.1 The 2009 revision of this method added Safety precautions), clarified identification of the testing endpoint (Note 1), and made minor adjustments to the text. T 825 om-14 Flat crush test of corrugated b
38、oard (rigid support method) / 4 10.4.2 The 2013 revision of this method moved the safety precautions earlier in the document and made minor editorial corrections to the text. Literature cited 1. Nelson, H. G., and Maltenfort, G. G., report of TAPPI Flat Crush Study, Tappi 44 (9): 614 (1961). Your comments and suggestions on this procedure are earnestly requested and should be sent to the TAPPI Standards Department.
