AS 1301.402:2019 pdf download.Methods of test for pulp and paper Method 402: Statistical monitoring of test systems for paper and paper board.
4 Principle
For a particular test, a series of randomized samples of reference material is prepared such that measurements can be made at a minimum of two, but preferably three, levels over the working range of the test scale. The reference material is as typical as possible in all physical respects of the material normally tested by the test system. The reference material is tested in accordance with the relevant Standard at appropriate intervals by the test system being monitored. The test results may be graphed on a chart that is used to judge the performance of the test system.
5 Selection of reference material
The reference material, grades and types of products shall be selected that are typical of the kinds of material which are normally tested by the test system or systems, and whose test values are distributed throughout the range of test values likely to be encountered.
At least two, but preferably three, reference materials of different test values shall be selected for a particular test. Where three are selected, their test values shall be in the low, medium and high sections of the working range. Where two are selected, one shall have a value towards the low end of the working range and the other towards the high end.
When grades and types of product are selected, the performance of the paper or paper board machine shall be monitored during the manufacture of each of the selected grades. A reel shall be chosen that was made in a period, not near the start or end of a making, during which the machine conditions were stable and from that part of the deckle where the cross direction (CD) variation in moisture, grammage and tests of interest is least. NOTE As shrinkage of paper is greatest on the paper machine towards the edge, which affects some properties, a centre reel should be selected. If the product is made on more than one paper machine, the machine that makes the least variable product shall be chosen.
6 Preparation of sample
6.1 General
During preparation, where the test property of the sample is sensitive to moisture content, the sample shall not be exposed to an atmosphere greater than 50 % RH.
6.2 Procedure
Preparation of the sample shall be as follows:
(a) Cut the reel (see Clause 5) into sheets whose size is a convenient multiple of the final specimen size plus trim allowance. If the test is directional, cut rectangular sheets rather than square sheets with the long side parallel to either the machine direction (MD) or CD. Record the means of identifying the direction. NOTE 1 Depending on the direction of the test, the long direction may be in either the MD or the CD.
(b) Place the sheets into stacks as they are cut and identify the stacks in order of cutting. (c) Select 20 sheets at random. Cut the sheets into specimens of a size convenient for cutting test pieces for testing purposes. Make approximately 60 tests in a single test system according to the standard method, cutting the minimum number of test pieces from each specimen.
(d) Determine the standard deviation of the replicate tests and assess whether it is low enough to enable the monitoring procedure to be sensitive at a low number of replicate tests (i.e. 10 tests).NOTE 2 No clear guidance can be given as to what is a satisfactory standard deviation; that depends on the size of differences that need to be detected.
(e) If the stacks are to be stored or transported at this stage, the requirements of Clause 6.4 apply.
(f) Take the stacks of sheets in order of cutting and cut into specimens of convenient size for cutting test pieces, being careful to ensure that MD and CD directions are identified and the dimensions in each direction are appropriate to the test. Place the specimens into stacks and identify the order of cutting of specimen stacks, keeping the specimens in the order in which they were cut.
(g) Mark all the specimens in one-fifth of the number of stacks by some suitable means, such as cutting off one corner or applying a dye to one or more edges.
(h) If the specimens are to be stored or transported at this stage, the requirements of Clause 6.4 apply.
6.3 Randomization of sample
6.3.1 Procedure
The choice of a procedure for randomizing the sample depends on the size or samp’e and the tacilities available. Whichever procedure is used, the sample shall pass the check for adequacy of randomization specified in Clause 6.3.2. NOTE Procedures for randomizing samples are given in Appendix A, but any procedure that achieves the desired result may be used.AS 1301.402 pdf download.