1. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),
ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 96-102 © IAEME
96
AN OVERVIEW OF PROCESS PARAMETERS OF MICRO GRAVURE
COATER TO IMPROVE THE QUALITY OF WET COATING
Pradip S Asodekar1
, Prof. Jeevan Salunke2
1
(M.E.Mechanical, IInd
Year, Deogiri Institute of Engineering and Management Studies,
Aurangabad(MS), India)
2
(Associate professor in .Mechanical Engineering, Deogiri Institute of Engineering and Management
Studies/ Aurangabad(MS). India)
ABSTRACT
Lamination is the process of applying the wet adhesive on the substrate. Later it is dried in
oven or by means of u .v. lamp. The process is accomplished with the help of a roll which revolves
in opposite direction to the web travel in an adhesive pan. The roll is engraved or the helical grooves
are cut on it with great precision. This roll is also called as gravure roll. In conventional gravure roll
the diameter of the engraved rolls are typically in the range of 125 to 250mm, but in micro-gravure
the rolls diameters is in the range of 20 to 50 mm.
The main objective of any lamination processes is to achieve the uniform & even coating
thickness & coating pattern. In this investigation an effective approach is based on experiments &
analysis of various process parameters, (e.g. viscosity, web speed, micro-gravure r.p.m.). These
experiments were conducted in the film mfg. company. The process parameters were analyzed to
find their effects on coating thickness, coating quality. From these experiments it concludes that the
quality of lamination, i.e. adhesive deposition(g.s.m.) is directly proportional to viscosity, micro-
gravure speed (r.p.m.) & inversely proportional to web speed (m.p.m.)
Keywords: Coating, Deposition (gsm), Lamination, Micro Gravure, Substrate, U.V. Lamp,
Viscosity.
1. INTRODUCTION
This research paper is aimed at improving our understanding of gravure roll coating process,
which is an important & widely used value adding process. In this process, a thin liquid film is
deposited on to a moving substrate in order to change its surface properties. A comprehensive
INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING
AND TECHNOLOGY (IJMET)
ISSN 0976 – 6340 (Print)
ISSN 0976 – 6359 (Online)
Volume 5, Issue 4, April (2014), pp. 96-102
© IAEME: www.iaeme.com/ijmet.asp
Journal Impact Factor (2014): 7.5377 (Calculated by GISI)
www.jifactor.com
IJMET
© I A E M E

2. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),
ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 96-102 © IAEME
97
understanding of the process has proved elusive. The development of the detailed model will have
significant benefit by analyzing the complex gravure roll coating process. The roll is not smooth the
helical pattern allowing faster operating speed & thinner liquid film to be deposited.
1.1 Types of Coating Process
Coating or the lamination is the process of applying the adhesive or a coat on the film
surface. The purpose is to improve the qualities of the film surfaces, to impart additional optical
qualities in the film surfaces. e.g.- to improve optical density, heat resistant properties, visual light
transmission, haze & clarity etc. There are many coating process available, direct or reverse gravure,
reverse roll, die coaters, wire bars, blade or doctor blade coaters, kiss gravure method
1) Standard gravure coating method - in this process a cylindrical gravure roll with diameters 125
to 250 mm used, which revolves in the adhesive pan in reverse direction. It is called reverse
gravure coating. When the roll rotates in the same direction as web travel it is called direct
coating,
2) Die coater - This is also a coating method in which adhesive passes on to the substrate through
very thin slot made, an adhesive pump is provided for adhesive circulation. Adhesive
deposition on the film surface is possible due to the vacuum provided. The thickness of wet
deposition can be varied with varying the speed of adhesive circulation pump
3) Mayor bar - It is a bar on which a thin stainless steel wire is wound on it. The extra adhesive
from the film surface is removed by the mayor bar & gives the uniform coating. The mayor bar
lines & orange peel are the prominent defect observed in this coating method.
4) Doctor blade - In this process a doctor blade is used to remove the excess adhesive from the
film surfaces.
5) Micro gravure - the method is same like the conventional standard gravure, the only difference
is its small diameter roll. It gives the excellent quality of coating & less variation of coating
thickness.
1.2 Micro Gravure Coating Process
Micro gravure is the reverse, kiss gravure coating method, the gravure roll (engraved
cylinder) roll rotates in the small adhesive pan with partially submerged conditions. It picks the wet
adhesive & transfers on to the film surface. A blade or knife is used to remove excess coating
solution. Without this, the cell volume could not be the major factor in determining the thickness or
the of weight of wet coating on the film. However the blade used is quite different from the blades
used in most of the gravure process. The major departure relates to stiffness & the angle of attack of
the blade to the roll surface. Micro gravure blades are quite thin and flexible in comparison to those
typically used gravure process. The pressure of the blade against the roll is rather light or even zero.
The angle of attack of standard gravure roll is steep. The line of the blade extensions typically passes
close to the roll center. The thin flexible Micro gravure blade lays on the roll, nearly tangent to the
surface. The comparison here is scraping action versus smoothing or metering action. In standard
metering causes, considerable wearing of blade & the roll surfaces occur. Thus the life of the blade
& roll is extended because of the more gentle action in micro gravure process.

3. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),
ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 96-102 © IAEME
98
2. COATING PARAMETERS & CONDITIONS
To achieve the good quality of coating, uniform coating thickness & change in coating
thickness, following are the parameters which affects mainly-
1) Viscosity - It is the flow ability of the liquid adhesive. It is measured in standard viscosity ford
cup, B2. The unit is in second, i. e. the amount of the time required in second for the adhesive
in emptying the ford cup. More the viscosity more will be the deposition (GSM). As the
viscosity decreases the deposition (GSM) also decreases.
2) Varying gravure speed (RPM) - By keeping the line speed (MPM) uniform, the gravure speed
(RPM) may be varied. The deposition increases by changing the speed ratio.
3) Using various types of gravure sizes (changing mesh, e.g. H04, H06, H09, H10, H11, etc).
According to the deposition requirement we may use the various gravure rolls for the specific
range. The gravure numbers in ascending orders shows coarse sizes of the gravures which
increases the depositions as the cell volumes in respective gravures increases.
4) Changing blade positions / Swivel positions - This is the fine tune to vary the deposition, the
blade position towards the gravure roll increases the deposition & the blade position away from
the gravure roll decreases the deposition.
Besides this the deposition (GSM), also depends on coating thickness of the web (micron), as
the thickness increases deposition decreases. Deposition also depends on film surface the rough
/corona treated, coated surfaces gives higher deposition than the smooth surface.

4. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),
ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 96-102 © IAEME
99
3. EXPERIMENTAL DETAILS
3.1 Design of Experiments
Various trials were conducted to set the required deposition on the micro gravure coater.
Following parameters were varied.
1) Adhesive batch viscosity - by keeping all the parameters constant batch viscosity varied from
90 sec to 120 sec the deposition (GSM) increases.
2) Varying gravure speed (RPM) - By keeping the line speed (MPM) constant, the gravure speed
(RPM) may be varied. The deposition increases by changing the speed ratio.
3) Changing blade positions / Swivel positions - This is the fine tune to vary the deposition, the
blade position towards the gravure roll increases the deposition & the blade position away from
the gravure roll decreases the deposition.
PARAMETERS RANGE TARGET
VISCOSITY (SECOND) 80- 120 SECOND 100 SEC.
LINE (WEB) SPEED
(MPM)
10- 18 MPM 14 MPM
GRAVURE SPEED (RPM) 101-163 RPM TO ACHIEVE THE
SPEED RATIO 120-130%
KISS COATING ROLL
POSITION
FRONT-35MM ,BACK-
25MM
ROLLS PERFECTLY
ALIGN
3.2 Selection of Control Factors
From the discussion with company people & with the help of research papers it is strongly
felt that the speed ratio – the ratio between line speed to gravure rpm is very important in micro
coater deposition (GSM) setting. So deposition is set as response parameters, as coating quality
depends on the even deposition.
3.3 Experimental Set Up
The essential equipment required for any gravure coating process is a micro gravure head,
coating pan, micro gravure roll having different meshes (e.g. – H04, H06, H09, H10, H11, H22, etc),
a servo motor to rotate the gravure roll, doctor knife & the circulation system which operates on
pneumatic pump.

5. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),
ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 96-102 © IAEME
100
Table- Specification & Description of the Machine
Specification Description
Web material PET FILMS
Web thickness 15-250 micron
Web width 1042mm to 1900mm
Machine speed Max 50m/min – Min. 3.0m/min
Coating thickness 0.6 GSM to 10.0 GSM
Dry zone type Air floating type ,UV Cure Type
Unwind Diameter Max 800 mm
Rewind Diameter Max 800 mm
Drive type Servo
3.4 Experimental Condition
By keeping all parameter / condition constant for monitoring the deposition the speed ratios
changed. Line speed 14 MPM kept constant & gravure speed in (RPM) changed. The relation
between line speed & corresponding gravure speed may be as –
Line speed (MPM) = Gravure Speed (RPM)
= π *D/1000* N
Where, D = Diameter of gravure roll. (50mm)
N = Gravure speed (RPM)
Following tables shows the results of coating quality & deposition increments with increase
in speed ratios when 38 to 42% solid solution is used
Deposition
(GSM)
0 0 2.5 3.15 3.6 3.85 3.8 3.9 4.0 4.2 4.3 4.2 3.9
Speed
Ratio
0% 20% 40% 60% 80% 100% 120% 140% 160% 180% 200% 220% 240%
Gravure
Speed
(RPM)
0 18 36 53 71 89 107 125 142 160 178 196 214
0
1
2
3
4
5
Speed Ratio
Deposition(GSM)
Deposition
(GSM)
Speed Ratio
From this experiment it is observed that the deposition increases as the speed ratio increases.
At speed ratio 200% the deposition goes on decreasing the graph shows the decreasing trend

6. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),
ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 96-102 © IAEME
101
TABLE – The relation between line speed & corresponding Gravure Speed ratio 1: 1
Line speed
(MPM)
0 2 4 6 8 10 12 14 16 18 20
Gravure speed
(RPM)
0 13 25 38 51 64 76 89 101 115 127
4. RESULT & DISCUSSION
The various trials conducted to see the effect of the deposition (GSM) & Coating quality At
Line Speed 14 MPM. It is observed that as the speed ratio increases the corresponding gravure rpm
also increases & corresponding deposition also increases.1 to 1 ratio is good starting point for
examination of few new coating. Some 100% solids formulations have been seen to exhibit rather
strange behavior relative to “typical coating” with 1 to 1 ratio although it is not surprising, to see a
departure from a typical 30-40% solid solution chemistry. On occasion the ratio of 2 to 1 or 3 to 1has
produced good coating with 100% solids UV or radiation curable.
At speed ratio 100 to 130% the variation in deposition in TD (Transverse Direction) is less
compared to speed ratio 200 & above this can be seen by observation & experiments.
5. CONCLUSION
The main objective of any laminating process is to achieve the uniform & even coating
thickness. To improve the quality of wet coating in laminating the window film production various
trials conducted using different parameters for example change in viscosity, line speed, coating
thickness of the film etc. From all these experiments it is concluded that micro gravure speed (RPM)
is important. The ratio of web speed to circumferential speed of the engraved roll is critical in
establishing the coating thickness (as per graph shown). At given web speed cylinder stationary, no
coating is transferred to the web, as rotational speed is increased, coating will start. Additional
rotational speed increases the coating weight until flooding or instability, and a decrease in weight
occurs. Coating weight (GSM) plotted against the speed ratio will generally show a bell-shaped
curve. The behavior of ‘typical’ coating will follow the pattern: at 50% to 60% of speed ratio the
coating starts, a smooth & uniform coating starts at 100 to 130%- weight increase, 200% or more
weight decrease & instability observes.
6. ACKNOWLEDGEMENT
The authors wish to acknowledge the support rendered by Mr. G.D. Joshi (Manager-Utility)
& Mr. Navin Saw (Production Officer) of Cosmo Films Ltd, Mr.P.G.Taur (HOD) Mech. Engineering
Dept. of Deogiri Institute of Engineering and Management Studies. Also acknowledge support of Dr.
Ulhas Shiurkar (Director) of Deogiri Institute of Engineering and Management Studies. To conduct
the study of the experiments. Who have encouraged and inspired for the success of this research
paper.

7. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),
ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 96-102 © IAEME
102
REFERENCES
[1] Coating materials & surface coating defects - By Tracton, CRP Press, By Taylor & Francis.
[2] A Hand book of Deposition technology for film & coating –By Peter M Martin
ISBN978-0-8155-2031-3.
[3] Analysis of Gravure roll Coating Process – by faculty of engineering.
www.engineering leeds.ac.uk.
[4] Microgravur by Yasui Seiki Co. US4.
[5] Electrophoretic Deposition of Nano materials –By James H Dickerson, Springer Publication.
[6] Dalip Kumar, Antariksha Verma and Sankalp Kulshrestha, “An Experimental Study of Wear
Resistance of Al – Sic Coatings on Steel Substrate”, International Journal of Advanced
Research in Engineering & Technology (IJARET), Volume 4, Issue 6, 2013, pp. 222 - 228,
ISSN Print: 0976-6480, ISSN Online: 0976-6499.