ISO 14968:1999 pdf free download

07-09-2021 comment

ISO 14968:1999 pdf free download.Paper and board – Cut-size office pap Measurement of curl in a pack of sheets.
Curl in cut-size office papers plays an important part in the performance of these papers in copying processes. Frequently, cut-size papers are used on copier and other printing devices, operating at high speeds. Curl which exists in the ream before the paper enters the imaging process. and curt developed during the imaging process, can affect office paper performance, especially if two-sided printing or collating is involved. Common pioblems experienced include jamming and misregistration.
The experience used in developing this test method was limited to uncoated papers in the commonly used cut sizes. The technique is basic and could be used with coated papers as well as paperboard to identity the type and magnitude of curl.
The test method identifies the type and degree of curl in a pack of sheets but does not address variations that might be present in individual sheets. The method of ISO 11556 can be used to measure curl in Individual sheets,
It should be recognized that the curl occurring after processing in a copier or a printing device may bear no relation to the curl of the paper as received.
curl magnitude
quantitative measure of the deviation of a paper test piece from a flat surface
NOTE 1 It is expressed as the reciprocal of the racus of curvature, R, of the curled test piece with units of reciprocal metres (rn-1).
NOTE 2 The radius of curvature for the curled test piece is the distance from the arc to the centre of a circle, of which the atc forms a part The reciprocal radius (R 1) has a value of zero for a flat sheet.
NOTE 3 Curl charactenstics of paper and board are timedependent and the magnitude of any curl may be transient.
curl axis direction
direction of the curl axis of paper and board, characterized as follows:
— curl axis which is perpendicular to the paper’s machine direction;
— curl axis which is parallel to the paper’s machine direction;
— curl axis which is neither parallel nor perpendicular to the paper’s machine direction.
NOTE See figures A.1 to A.3 respectively.
concave side
side towards which the paper or board curls
NOTE See also annex A.
double curl
form of curl which tends to alternate between the two sides, when the sheet is manipulated lightly
NOTE This tendency is a phenomenon which may be described as two curl patterns that are finely balanced within the same sheet 01 paper.
cut-size office papers
papers in the range 60 g/m2 to 150 g/m2 which are used for writing and/or in various printing and copying devices
The purpose of this method is usually to test the inherent curl of the paper at the moisture content that it has immediately following its removal from a ream, or after processing in a copier or other printing device.
In this case the paper shall not be conditioned in a standard atmosphere. The actual testing may be carried out either in the standard atmosphere described in Iso 187, or under the measured ambient conditions of the area surrounding the imaging device.
7 Sampling
7.1 If tests are being made to evaluate a lot, the sample shall be selected in accordance with ISO 186:1994, 5.1.
7.2 For the purposes of ISO 14968, a test piece is understood to be a pack of 10 to 15 consecutive sheets.
7.3 When taking paper from unopened packages, open the package, pull out 10 to 15 consecutive sheets and make the measurement, in accordance with the procedure (clause 8). To ensure that only samples which have experienced minimum exposure to the atmosphere are selected, do not pull sheets from near the top or bottom of the pack.
7.4 When taking paper from stacks that are not wrapped, pull 10 to 15 sheets from some distance down the stack so as to avoid paper that has been exposed to the atmosphere. Make the measurement, in accordance with the procedure (clause 8) without delay.
7.5 Identify the machine direction and referenced side of the paper.
NOTE 1 The referenced side is the side that should be imaged first.
NOTE 2 If the machine direction (MD) is unknown, it may be determined by reference to the Bibliography.
7.6 When sampling paper after copying or from a printing device, allow at least 2 mm of continuous operation for a stack to build and then pull out 10 to 15 sheets from the machine and make the measurement in accordance with clause 8 without delay. Do not pull sheets from the top or bottom of the printed stack.
8 Procedure
8.1 It is recommended that the curl for all four edges be measured, except when there is a very dominant curl with axis parallel or perpendicular to the papers machine direction. In this case only the curl of the two short or two long edges needs to be measured. The procedure that follows applies to all four edges of the test piece. If no dominant curl is apparent, begin at any of the four edges.
8.2 Select the test piece In accordance with 7.3, 7,4 or 7.6.
8.3 Hold the test piece on one edge vertically between the thumb and forefinger at mid-height. about 10 mm from the edge. Immediately superimpose the opposite tree edge without contact over the curl gauge arcs and read the radius of curvature for whichever arc is the nearest match to the test piece.
NOTE In the event of a diagonal curl, a more accurate estimate of the curl magnitude can be obtained if the test piece is suspended at such a point on its edge that the curl axis is vertical. Using a set of templates as suggested in note 2 of 5.1 will facilitate this measurement.
8.4 For non-processed test pieces, record the side towards which the paper curls, that is, towards or away from the referenced side, For test pieces processed through a copier or other printing device, record whether the test piece curls towards or away from the last imaged side.
NOTE For determining curl after copying or processing through a printing device: if there is significant splaying in the pack of sheets, such that no single curl value can be measured, ills probable that the copier or printer has not reached a satisfactory operating temperature. In this case it is advisable to rerun the test after feeding at Least 100 copies through the machine betore pulling out the test sheets.

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