Иш кетма-кетлиги

Control questions: 
1. What does the amount of ash give information about? 
2. What formula is used to calculate grayness? 
3. How to achieve a constant weight? 
4. What is the purpose of placing a sample in a desiccator? 
5. Where is the paper sample burned? 
 
 
 
4 – LABORATORY WORK 
DETERMINE THE ROUGHNESS OF THE PAPER 
 
 
The purpose of the work: to learn the method of studying the relief of the paper 
surface and assessing its roughness. The student should pay attention to the causes of 
microuniformity and macrouniformity in paper, because these factors have an 
important impact on obtaining a quality result during the printing process. Smoothness 
is determined on a pneumatic device. 
Tools and equipment: 
 
 
The TP300 device is a device that determines the roughness of the paper 
surface 
The TP300 is designed to measure and test paper surface roughness, waviness 
and initial profile. 
Measurement parameters meet the international standards of developed countries 
USA, Germany, Japan and Great Britain. The measurement results can be displayed on 
the LCD in digital or graphic size. 
TECHNICAL DESCRIPTION 
Measuring roughness, ripple and initial profile 
Dimensions of R are Ra, Rp, Rt, Rz, Rq, RS, Rsm, Rc 
Wave filter RC, PCRC, Gaussian, ISO 13565 
Shear 0.08mm, 0.25mm, 0.8mm, 2.5mm, 8mm. 
The maximum range is 800 μm 

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Max. Accuracy 0.001 µm/50 µm 
Accuracy ± 5% 
Mains powered Li-ion battery/external adapter 
 
Theoretical part 
One of the most important properties of the paper is to create an image on the 
surface of the printed material during the printing process. Wrinkling of paper is 
related to irregular arrangement of fibers on the surface of paper sheet. On the 
contrary, when pressing on the surface of corrugated cardboard by the flexographic 
printing method, the paint layer penetrates the porosity of the printed material and 
creates the spreading of raster dots. It is impossible to obtain paper with a completely 
smooth surface, and it is impossible to create a printing process on a smooth surface. 
The printing process is formed on uneven surfaces. The surface of paper is always 
formed as a result of microporosity, interlinking of fibers during the production 
process, and the presence of irregularities on its surface. When the process of 
smoothing the paper surface is not carried out, roughness is formed, besides, the 
roughness is higher on the opposite side of the sheet. 
It should be noted that the accurate determination of the value of roughness is 
one of the most important tasks of metrology. Balance roughness - parameters GOST 
2789-73 "Surface roughness. "Parameters, characteristics and symbols" are defined. 
The surface roughness of the paper 
According to this normative document, the indicators of paper quality are as 
follows: 
• Ra is the arithmetic average value of the profile deviation. 
• Rz - the height of profile irregularities obtained at 10 points. 
• S is the average step of local protrusions of the profile; 
• Sm - average arithmetic value of roughness step; 
• Rmax - the maximum height of the profile; 
• tp is the relative length of the profile (reference), p is the level of the profile 
part. Surface porosity of top liner and liner fluting paper was determined by GOST 
25142-82 [+]. Corrugation of corrugated cardboard was determined by TR 300 
equipment.