Mapping local thickness - Innventia.com

STFI Local Thickness – a tool to mapthe local thickness in two dimensionsSeptember 2009The local thickness in a paper sheet is measured in two dimensionsand can be related to other local measurements of e.g. grammage,gloss or print density.Combining local thickness and local grammage gives an image of local density. This methodcan be applied to relate local density variations to local variations in print density (i.e. mottle)or gloss.Another application is to study how thickness variation decreases and density variationincreases as an effect of calendering under different conditions.ExampleThe thickness distributionbefore and after water applicationon a calendered paper reveals itsswelling behaviour.Realtive frequency0.20Before water appl.0.18After water appl.0.160.140.120.100.080.060.040.020.0090 95 100 105 110 115 120Thickness [µm]How this is madeThe paper sample is mounted in an XY-table where the thickness of the sheet is measuredbetween two spherical probes with a diameter of 1 mm.INNVENTIA ABBox 5604, SE-114 86 Stockholm, SwedenTel +46 8 676 70 00, Fax +46 8 411 55 18info@innventia.comwww.innventia.com

2(2)The data are collected either along tracks or as a matrix. From the thickness data the variationis calculated and divided into wavelength classes.Standard setting for 2D measurements:Standard setting for 1D measurements:The maximum sample size is 75x120 mm.256x256 measuring points150 µm between the points1024 measuring points per track110 µm between the points3 mm between the tracksWhat you get2D measurement• Images (see below) saved in a Word file or as data in a MATLAB file.• Calculation of a new property by matching the thickness data with other local data, e.g.calculate a density image from local thickness and local grammage.Thickness image Grammage image Density image1D measurement• A thickness spectrum where the thickness variation is presented with the coefficient ofvariation (CV) divided into wavelength classes, i.e. a description of the geometrical sizedistribution of the thickness variation in the paper sheet.ContactFor more information about the method, prices etc. contact:Hans ChristianssonPhone: +46-8-676 73 81hans.christiansson@innventia.comMargareta LindPhone: +46-8-676 72 74margareta.lind@ innventia.com