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1、T 549 om-08 PROVISIONAL METHOD 1990 OFFICIAL METHOD 2001 REVISED 2006 REVISED 2008 2008 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 in connection with the
2、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 this Test Method TAPPI CAUT
3、ION: 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 safety precautions are com
4、plete 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. Procedures for the handling of
5、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 determine whether any of th
6、e 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. Coefficients of static and kinetic friction of uncoated w
7、riting and printing paper by use of the horizontal plane method 1. Scope 1.1 This method describes a horizontal plane procedure for the determination of the coefficient of static and kinetic friction of paper measured when sliding against itself. 1.2 The horizontal instrument requires some means of
8、movement of the specimen in relation to the surface upon which it rests. The coefficient of friction (COF) is measured directly from the resistance to tangential motion and the applied weight pressing two pieces of paper together. 1.3 Static COF relates to the force required to initiate movement bet
9、ween two surfaces while kinetic COF relates to the force required to cause continuation of the movement at uniform speed. 1.4 The determinations of COF for packaging materials is described in TAPPI T 815 “Coefficient of Static Friction (Slide Angle) of Packaging and Packaging Materials (Including Sh
10、ipping Sack Papers, Corrugated and Solid Fiberboard) (Inclined Plane Method).” In the method for testing packaging materials, the force measurement is often made on the third slip, while in this method the determination is made on the first slip. 2. Applicable documents 2.1 TAPPI Test Methods: TAPPI
11、 T 400 “Sampling and Accepting a Single Lot of Paper, Paperboard, Containerboard, or Related Product;” TAPPI T 402 “Standard Conditioning and Testing Atmospheres for Paper, Board, Pulp Handsheets, and Related Products;” TAPPI T 409 “Machine Direction of Paper and Paperboard;” TAPPI T 455 “Identifica
12、tion of Wire Side of Paper;” TAPPI T 494 “Tensile Breaking Properties of Paper and Paperboard (Using Constant Rate of Elongation Apparatus).” 2.2 ASTM Standard D 3460 “White Watermarked Bond and Unwatermarked Bond, Mimeograph, Duplicator, and Xerographic Cut-Sized Office Papers.” T 549 om-08 Coeffic
13、ients of static and kinetic friction of uncoated writing / 2 and printing paper by use of the horizontal plane method 3. Terminology 3.1 Friction, the resisting force that arises when a surface of one substance slides, or tends to slide, over an adjoining surface of itself or another substance. Betw
14、een surfaces of solids in contact there are two kinds of friction: (1) the resistance opposing the force required to start to move one surface over another, and (2) the resistance opposing the force required to continue moving one surface over another at a constant speed. 3.2 Coefficient of friction
15、 (COF), the ratio of the frictional force resisting movement of the surface being tested to the force applied normal to that surface (the weight of the material above that surface). 3.3 Coefficient of static or starting friction, the ratio of the force resisting initial motion of the surfaces, to th
16、e normal force. 3.4 Coefficient of kinetic or sliding friction, the ratio of the force required to sustain the uniform relative movement of the surfaces, to the normal force. 4. Summary of method One specimen of the paper sample is clamped to a horizontal plane surface, the other to a specimen sled.
17、 The sled is pulled across the surface, or the plane pulled under the stationary sled and the force required to do so is measured. The coefficients of both static and kinetic friction may be determined. 5. Significance and use 5.1 The coefficient of friction of printing and writing papers is an indi
18、cator of the ease with which the top or bottom sheets of a stack of paper will slide across the succeeding sheet, such as occurs on the infeed of a printing press or the sheet transport into a copier machine. A minimum value of coefficient of friction is required to prevent double- feeding of any sh
19、eets. 5.2 Since each sheet is removed from the stack only once, a single slide of each pair of specimens is performed and the value recorded. 6. Apparatus (Fig. 1) 6.1 Horizontal plane and supporting base, a horizontal plane surface of a smooth, incompressible material - metal, hardwood, plate glass
20、 or plastic, having a width at least 25 mm (1 in.) wider than the specimen sled (see 6.2). The plane is mounted on a supporting base provided with means of leveling in two directions. A constant rate-of-motion tester, as described in TAPPI T 494, has also been found suitable. If this type of tester
21、is used, the horizontal plane and supporting base are one and the same. 6.2 Specimen sled, a sled or specimen block made of an incompressible 63.5-mm (2.5-in.) square metal block weighing 200 5 g has been found satisfactory. The precision statement is based on a sled of that size. The lower surface
22、of the specimen block shall be backed with a compressible backing made from a sheet of closed cell neoprene cellular rubber, with a thickness between 1.5 mm and 3.0 mm. The backing shall have a uniform thickness and shall be replaced if its edges become worn or its surface becomes damaged. A means f
23、or clamping the specimen to the sled may be provided, but it is not necessary if the lower surface is faced with 3-mm (0.12-in.) thick backing. A means for fastening the sled to the force measuring device, such as a wire cable or nylon filament line, is required. Take care in selecting a wire cable
24、or nylon filament line to make certain that its ability to stretch does not interfere with the measurement of force. The sled may be directly connected to the load cell. 6.3 Mechanical power unit, means for moving the specimen sled horizontally along the plane surface, or the plane surface under the
25、 specimen sled at a uniform speed of 150 30 mm/min (0.5 0.1 ft/min). A constant rate-of- motion tester equipped with a load cell in its upper crosshead and a constant rate-of-motion lower crosshead has been found satisfactory (T 494). -,-,- 3 / Coefficients of static and kinetic friction of uncoated
26、 writing T 549 om-08 and printing paper by use of the horizontal plane method Fig. 1. Schematics for two horizontal plane instruments. A tensile tester fixture and a horizontal tester. 6.4 Force measuring device, means for measuring the force required to move or restrain the specimen sled to the nea
27、rest 5 gf (0.01 lbf). A force gauge or the load cell of a constant rate-of-motion tester have both been found suitable. NOTE 1: Exercise care so that vibration from the drive motor or other sources does not affect measurements. 6.5 Paper cutter, to cut test specimens. 7. Sampling and test specimens
28、NOTE 2: See Appendix A.1. 7.1 If a lot of paper is being tested, select the sample in accordance with TAPPI T 400. The sample should be in the form of a finished ream or a “lift” sample from a roll. A lift is a stack of sheets about 1.3 cm (0.5 in.) cut from a roll. 7.2 Precondition, condition, and
29、test in the atmospheres as described in TAPPI T 402. 7.3 Cut the sample into test specimen pairs as follows: NOTE 3: Exercise care in cutting test pieces to avoid rough, damaged edges. 7.3.1 Finished ream samples. 7.3.1.1 With machine direction COF. Lift off a stack of six consecutive sheets, identi
30、fy the machine direction (T 409) and the felt (or top) side (TAPPI T 455) of the top sheet, and cut two specimens from each sheet: one 100 215 mm (4 8.5 in.) and the other 75 130 mm (3 5 in.). Cut the specimens so that the machine direction is parallel to the long dimension. Stack the two sets of sp
31、ecimens in separate piles, maintaining the same order of sheets as in the ream. Take the top sheet off the pile of larger specimens and discard. Use the second large specimen with the first small tensile tester Moving Element with Load Cell Sled Specimen Sled Moving Element with Load Cell Sled Rubbe
32、r Face Direction of Movement Direction of Movement Direction of Movement Pulley String String -,-,- T 549 om-08 Coefficients of static and kinetic friction of uncoated writing / 4 and printing paper by use of the horizontal plane method specimen, the third large specimen with the second specimen, an
33、d so on, performing the test with five pairs of specimens from consecutive sheets. Discard the one leftover small specimen (sixth). 7.3.1.2 Across machine direction COF. Follow directions given in 7.3.1.1, except: Cut the specimens so that the machine direction is parallel to the shorter dimension.
34、7.3.2 Lift sample. 7.3.2.1. With machine direction COF. Lift off a stack of at least seven consecutive sheets, identify the machine direction and the felt (or top) side of the top sheet, and cut two specimens from each sheet: one 100 215 mm (4 8.5 in.) and the other 75 130 mm (3 5 in.). Cut the spec
35、imens so that the machine direction is parallel to the longer dimension. Discard the top sheet from each stack and test five pairs of specimens. Each pair is from the same sheet. Discard the bottom sheets. 7.3.2.2 Across machine direction COF. Follow directions given in 7.3.2.1, except: Cut the spec
36、imens so that the machine direction is parallel to the shorter dimension. Discard the top sheet from each stack and test five pairs of specimens. Each pair is from the same sheet. Discard the bottom sheets. 8. Procedure 8.1 Place the instrument on a solid and vibration-free table and level it. If a
37、constant rate-of-motion tester is used, set it up according to its instructions for coefficient of friction determination. If necessary, adjust the force measuring device to zero. 8.2 With machine direction COF. Select the specimens cut with the grain direction parallel to the long dimension, 7.3.1.
38、1 or 7.3.2.1. See Appendix A.2. 8.2.1 Place the longer of each specimen pair on the horizontal plane with the top (felt) side upward and clamp or otherwise attach the end farthest from the force measuring device to the plane. 8.2.2 Place the smaller specimen on top of the larger with the wire side f
39、acing down, and set the rubber-faced sled lightly atop it. Or attach the smaller specimen to the sled and position the sled atop the larger specimen. NOTE 4: Exercise care in placing the sled on the lower test piece. Place the sled directly on the lower piece without any horizontal motion. 8.2.3 Att
40、ach the cable from the power unit or force gauge to the sled. 8.2.4 Start the power unit, making sure the cable remains taut (on instruments so equipped) as the drive takes up the load. No immediate relative motion may take place between the sled and the plane until the pull on the sled is equal to,
41、 or exceeds, the static frictional force acting at the contact surfaces. Record this initial, maximum reading, or note the maximum peak recorded on the strip chart recorder of the constant rate-of-motion tester, as the force component of the coefficient of static friction. Do not include the static
42、value, 8.2.4, in the kinetic readings. It is recommended that the time between placing the sled on the sample surface and start of test motion be consistent. 8.2.5 Continue the motion of the two specimens for a distance of about 130 mm (5 in.). Record the average force reading during this period, or
43、 obtain the average force by integrating the recorded trace on the strip chart recorder of the constant rate-of-motion tester, as the force component of the coefficient of kinetic friction. 8.2.6 After the sled has traveled the required distance, stop the power unit, remove the specimens, and return
44、 the apparatus to starting positions. Continue to test the remaining specimen pairs in identical fashion. No specimen pairs shall be tested more than once unless such tests constitute one of the variables to be studied. 8.3 Across machine direction COF. Select the set of specimens cut with the machi
45、ne direction parallel to the short dimension, 7.3.1.2 or 7.3.2.2. Repeat the procedure described in 8.2.1 through 8.2.6. 9. Calculations 9.1 Calculate for each specimen pair the coefficient of static friction as follows: COF static = force required to initiate motion, in mN / (sled mass, grams 9.806
46、65 m/s2) 9.2 Calculate for each specimen pair the coefficient of kinetic friction as follows: -,-,- 5 / Coefficients of static and kinetic friction of uncoated writing T 549 om-08 and printing paper by use of the horizontal plane method COF kinetic = average force reading during uniform sliding, in
47、mN / (sled mass in grams 9.80665 m/s2) NOTE 5: COF static and COF kinetic, calculated using the 9.1 and 9.2 equations and units, are unitless coefficients. Hardware and software systems that will perform all calculations required are available. 10. Report 10.1 Report as coefficient of static frictio
48、n, the average and standard deviation of the five determinations separately for each principal direction. 10.2 Report as coefficient of kinetic friction, the average and standard deviation of the five determinations separately for each principal direction. 10.3 Report whether the sample is taken fro
49、m a finished ream or a lift. 11. Precision 11.1 The following estimates of repeatability and reproducibility are based on data from the CTS-TAPPI Interlaboratory Program from 1996 through 1999. The individual analyses on which this data is based can be found in reports 164G through 179G. All samples on which this data is based were uncoated printing and writing grades. Data is based on 32 different analyses for both stati