IRJET- Design and Development of Paint Viscosity Controller

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 06 Issue: 10 | Oct 2019 www.irjet.net p-ISSN: 2395-0072
© 2019, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 623
Design and Development of Paint Viscosity Controller
Saurabh Vilas Gawali1, Vinay Tulshiram Sawant2, Rushikesh Rajendra Suryavanshi3,
Swapnil Vijay Narkhede4, Amar Tanaji Biradar5
1,2,3,4,5Department of Mechanical Engineering, JSPM’s Rajarshi Shahu College of Engineering, Pune,
Maharashtra, India
----------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - This dissertation concentrates on designing a
fully automatic paint viscosity controller closedloopsystem. If
the paint has high thickness it takes more time to dry out
which results in less productivity. Similarly, very thin paint
results in bad quality of work. How the specific amount of
thinner can be added into the paint and the viscosity can be
controlled automaticallyisexplainedhere. Thenewlydesigned
system gives a perfect layer of paint which reduces the
rejection rate of products and helps to increase the profit
amount. The manual interface is totally removed in the new
design to avoid human errors and. Theautomationofsystemis
achieved by using Programmable Logic Controller (PLC).
Key Words: automatic, paint, viscosity controller,
productivity, quality, rejection rate, errors, PLC.
1. INTRODUCTION
Existing system is having multiple problems like; open tank
of thinner which results the thinner to get evaporated as it
has vicinity to the air, uneven layer of paint is generated
because of uncontrolled viscosity of the paint, extra thick
layer results in excess time requirement to dry the paintout,
extra thin paint results in a very poor quality of paint layer
generation and an open system needs human interface to
operate the machine. The newlydesignedsystemovercomes
each problem of this list.
The objective of the new machine is to provide completely
closed loop system for proportionate mixture of paint and
thinner, save the cost and material, ensure proper quality of
the paint layer, minimise the product rejection rate and
increase the profit.
2. DESIGN
This machine is specifically designed to achieve an exact
viscosity value of the paint which will be used for painting
various objects according to need. Measurementandcontrol
of viscosity of paint is done by using viscosity sensor.
Viscosity of the paint is one of theimportantparametersthat
give a perfect layer of paint on the product. The rotating
spool of the viscosity sensor is operated by the servomotor
which runs in the paint and thinner mixture.
Fig – 1: Proposed model
The pipe which connects the pump and sensor has a
normally open type solenoid valve SV1 which controls the
flow to the sensor. Another pipe which isbetweenpumpand
the place of use is controlled by normally closed type
solenoid valve SV2. The intention behind keeping such
arrangement is to check the mixture before actual use.
Mixture flows through SV1 to the sensor where viscosity of
the mixture is checked.
Indication of green light by sensor gives the certification of
meeting the required viscosity. This happens because the
PLC is programmed to satisfy this condition according to
needs. PLC triggers the system and then SV1 closes with
opening SV2 which makes the mixturetoflowtothepainting
unit. This opening and closing cycle of SV1 keeps on running
to continuously have a check on viscosity of the mixture as it
may change during the working conditions.
When the viscosity of the mixture is not as per the
requirements, the sensor gives an indication of red light. As
well as sensor display actual viscosity of the mixture. The
programming of the system is such that, it calculates the
difference between actual and required values of viscosity
and then adds the amount of thinner/paint as per the
requirements. SV3 is operated to add the amount of thinner
to the mixture to achieve the exact viscosity as per the
requirements. The mixer mixes the mixture of paint and
thinner continuously. Blades are placed to completethetask
of mixing. In the actual model, the force exerted by the
mixture on the mixing blades is used to determine the
viscosity of the mixture. The load on the blades increases
with increase in viscosity and vice versa. It is little
challenging to calculate the load accurately. Servo motor is
used to determine this load. RPM of the motor is kept

constant and then the load is calculated according to the
consumption of current by the motor. PLC records the
readings and compares it with different reading at specific
intervals of time.
3. MATERIAL SELECTION
1. Motor
Given = 220 volts, 0.0018 ampere.
i. Power
P = V * I
= 220 * 0.0018
= 0.3987 KW
= 0.4 KW
ii. Torque
P = (2*π*N*T)/60 W
400 = (2*3.14*3000*T)/60 W
T = 1.273885 Nm
2. Shaft
For 400W, 0.4KW Delta ECMA – C30604FS 60mm
motor, shaft diameter available is 12mm. So we
need to select the shaft with outer diameter 12mm.
Length of shaft is taken as 40mm, according to the
height of mixing tank.
Blades
Blades size is decided according to the amount of
colour in litres.
Sr.
No.
Blade Size
(Diameter*Thickness in mm)
Paint quantity
(Liters)
1. 40 * 1.5 5-10
2. 70 * 1.8 15-40
3. 120 * 2.2 50-250
4. 145 * 2.2 200-700
Table – 1: Standard Blade Sizes
3. Couplings of Shaft.
Diameter = 40mm.
Inner Diameter = 12mm.
Length = 30mm.
4. WORKING
Fig – 2: Working setup
The setup consists of Servo Motor, Servo Drive, Thinner
Tank, Programmable Logic Controller, Human Manual
Interface, Solenoid Valve, Flow Sensor and Variable Flow
Control Valve. Initially the raw paint with extremely high
velocity is poured into the mixing tank. Nowtheservomotor
is turned ON which is operated by servo drive. The thick
paint exerts pressure on the mixing blades attached to the
motor shaft. The current consumption by the motor is
identified and RS485 command is sent to the PLC by the
servo drive. The force exerted by the paint on the blades is
very high initially because of high viscosity and therefore
high load on the motor take more current consumption.
PLC compare the value with pre-set required valueandsend
the command to variable flow control valve. The thinner is
added to the mixing tank through solenoid valve, variable
flow control valve and flow sensor. After adding thinnerinto
the paint, viscosity of the paint starts reducing. This results
in less force acting on the mixing blades and further less
consumption of current bythemotorwhichshowsreduction
of viscosity via command RS485.
The flow sensor works as a feedback loop. Itgivesthedata to
PLC which is related exact amount of thinner added into the
mixing tank. Exact value of the Viscosity of the paint is
calculated in the Programmable Logic Controller and then
further it is displayed on the Digital ScreenatHumanManual
Interface (HMI).
In case if the tank is open to the environment and paint is
stored in the mixing tank only then high vicinity of thinner
to the environment results in automatic increase in the
viscosity of the paint. In this case we need to turn on the
servo motor once again before using that paint for painting
the required objects.

5.ANALYTICALMETHODTOCALCULATEVISCOSITY
Fig – 3: Dimensions of Tank
The shaft which is connected to the blades is rotating at
1000rpm. Diameter of shaft and blade is 12mm and 90mm
respectively. Torque of the motor usedtorotatethebladesis
1.27Nm. The task of mixing is carried out in a cylindrical
tank of diameter 300mm and height 400mm. Paint is filled
up to height 304.8mm. Calculate the dynamic viscosityofthe
paint.
Given:
N = 1000 rpm
T = 1.27 Nm
d1 = 12 mm = 0.012m
d2 = 90 mm = 0.09 m
D = 300 mm = 0.3 m
H (fluid height) = 304.8 mm = 0.3048 m
To Find: µ =?
1) Velocity of mixing blades
Du = [(3.14*d2*N)/60]
= [(3.14*0.09*1000)/60]
= 4.712388 m/s
2) Remaining distance of fluid around the blades
Dy = D-d2
= 0.3-0.09
= 0.21 m
3) According to Newton’s Law of Viscosity, rate of
Shear stress is directly proportional to rateofShear
strain.
Shear Stress = µ*[Du/Dy]
Shear Stress = F/A
Therefore;
F = Shear stress * Area
= T/r1 (motor give speed to shaft first)
= 1.27/ (0.012/2)
= 211.6666N
Area = 2*3.14*R*H (cylindrical tank)
= 2*3.14*0.15*0.3048
= 0.28726 sq. m
F = Shear stress * Area
211.66 = {µ*[Du/Dy]}*0.28726
= {µ*[4.712388/0.21]}*0.28726
736.84 = µ*22.4399
µ = 32.8363 Poise
= 32.8363*10^3 cP
The dynamic viscosity of the paint is 32.8363*10^3
cP.
5. CONCLUSIONS
From the above results, conclusions drawn are;
1. The current paint mixing machine has manually
interfered thinner and paint mixing systems, which
results in uneven mixture, play with the required
viscosity value and high product rejection rate. All
these problems are eliminated byintroducingafully
automatic unit.
2. Continuous monitoring of the viscosity of paint and
thinner mixtureis done at regular intervals byusing
PLC.
3. Exact viscosity of the paint is achieved by adding a
specific amount of paint and thinner in the tank by
using different solenoid valves and this viscosity is
compared to the pre-set value by using sensors and
PLC to achieve the accuracy.

REFERENCES
[1] Panas A J, (2017) Investigation of thermophysical
properties of thin-layered pain. Elsevier Journal, the
National Centre for Research and Development, Poland,
Research Project No DOB-BIO8/04/01/2016.
[2] Khajorntraidet C, Torque Control for DC Servo Motor
Using Adaptive Load Torque Compensation, the
research grant from SuranareeUniversityofTechnology
(SUT) ISBN: 978-960-474-230-1.I.C.
[3] Bloomfield V A, (1971) Viscosity of Liquid Mixtures.The
Journal of Physical Chemistry, Publicationcostsassisted
by The National Institutes of Health Vot. 76, No. 20,
1071.
[4] Brian Cherrington & Rothstein J, BuildingandValidating
a Rotational Viscometer.
[5] Kumar B, (2017) Vortex Depth Analysis in an Unbaffled
Stirred tank with Concave Blade Impeller, Chem.
Technol., 2017, Vol. 11, No. 3, pp. 301–307.
[6] DR. R. K. Bansal, “FLUID MECHANICS AND HYDRAULIC
MACHINES” Laxmi Publications.

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