Formulation of field databased model a case study at pvc pipe manu

International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 3, May - June (2013) © IAEME
94
FORMULATION OF FIELD DATABASED MODEL: A CASE STUDY
AT PVC PIPE MANUFACTURING INDUSTRIES
Vikhar A D* Dr. Modak J.P#
* Ex. Associate Professor in Mechanical Engineering, (SGDCOE), Jalgaon (MS),
Faculty in Mechanical Engineering, DTE, Government of Maharashtra,
Government Polytechnic, Khamgaon.
# Ex. Head, Dept. of Mech. Engg., VNIT, Nagpur, Emeritus Professor in Mechanical
Engineering, Dean (R & D), Priyadarshini College of Engineering, Nagpur.
ABSTRACT
Extrusion of PVC pipe is a steady-state process for converting a thermoplastic raw
material to a finished. The raw material is usually in the form of plastic pellets or powder.
The conversion takes place by forming a homogeneous molten mass in the extruder and
forcing it under pressure through an extrusion die orifice that defines the shape of the
product's cross section. The formed material, or extrudate, is cooled and drawn away from the
die exit at a controlled rate. The extrudate can then be wound on a spool, cut to a specified
length, or directed into another in-line process. In this paper a field databased mathematical
model is formulated by considering the different important input parameters on which affects
the total production output. After evaluation of this model by applying the weighted value
technique it is found that the key to successful, efficient extrusion processing is found in
taking every parameter that can affect the manufacturing system, and identifying it,
controlling it, or monitoring it. The extrusion of pipe is a steady-state process. Anything that
happens that alters the steady-state condition will disrupt the steady-state condition and create
variation in the product quantity and quality.
Keywords: Mathematical modeling, plastic extrusion, PVC pipe.
INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING
AND TECHNOLOGY (IJMET)
ISSN 0976 – 6340 (Print)
ISSN 0976 – 6359 (Online)
Volume 4, Issue 3, May - June (2013), pp. 94-99
© IAEME: www.iaeme.com/ijmet.asp
Journal Impact Factor (2013): 5.7731 (Calculated by GISI)
www.jifactor.com
IJMET
© I A E M E

95
1. INTRODUCTION
Polyvinyl-Chloride (PVC) is a plastic product which has matchless versatility. It
effectively replaces wood, paper and metal in several applications. As such plastic pipes have
been progressively replacing conventional pipes like G.I., Cast Iron, Asbestos Cement or
Stone-ware for a number of important and uses. Among the various types of plastic pipes
which are commonly used for such applications PVC pipes are the most widely used all over
the world on account of their most favourable balance of properties. PVC pipes are light in
weight, rates for use under pressure, easy to install, low frictional loss, low on maintenance
cost, and have low frictional loss. Rigid PVC pipes have wide variety of uses in fields like
city/town/rural water supply scheme, spray irrigation, deep tube well schemes and land
drainage schemes.PVC pipes are used for a variety of purposes e.g. water supply schemes,
spray irrigation, deep tube well schemes and land drainage schemes. PVC slotted and
corrugated pipes are ideal systems for drainages of water from land where water logging is
inevitable. It is widely used by various utility services now-a-days too. The major consumer
of PVC pipes are the Public Health Engineering Department (PHED) and Irrigation
Departments. Besides these two, it is used by the Municipal Corporations, Tea estates as well
as in N.E. Region. The usage of PVC pipes also depends upon the size of these pipes too. It is
manufactured in different sizes having innumerable usage value.
2. PVC PIPE EXTRUSION
Extrusion is the basic process for converting thermoplastic resins into continuous
lengths of shapes having uniform cross-section. It is indicated for standard profiles such as
sheet, film, tubing, rods, and custom profiles of any shape. The overall processing cycle
consists of melting the raw material, usually in pellet form, extruding the molten resin
through a die that forms the shape of the final part, and then hardening the continuously
extruded shape by cooling it as it emerges from the die. The continuous lengths are then
reeled or cut to desired length.
Extrusion generally involves using a screw [1] [2] that advances the raw material or
resin from a feeding hopper through a melting zone. The melted material is forced through an
orifice in the die that defines the shape of the end product. The extrusion screw provides
frictional heat to help melt the resin, and creates the force to form the desired shape in the die
with the pressure needed to obtain the necessary product density. External heat is also applied
to the extruder barrel as required. Selection of the feed screw is paramount, since this will
dictate whether maximum production rates are achieved, and whether the final product
quality is satisfactory.
3. SINGLE SCREW EXTRUDER
By far the most common and most versatile extruder in use today is the single-screw
extruder [1]. Single-screw extruders are characterized by two dimensions; the bore diameter
(D), and the length of the barrel in bore diameters or L/D ratio. The barrel of a single-screw
extruder usually is a long, thick walled tube of alloy steel, into which a hard, highly
crystalline wear-resistant alloy has been centrifugally cast. Attached to the feed end of the
barrel (often as a separate casting) is an opening into the barrel bore for feeding the raw
material. It is usually jacketed for room temperature water-cooling to prevent premature

96
melting of polymer. The barrel must be provided with the means to both add and extract heat.
Though heaters vary in design, the most common ones are cast aluminum. The heater halves
are clamped to the barrel to provide intimate contact between the steel of the barrel and the
aluminum of the heater. The heat sink is either air or a liquid coolant. Inside the barrel is a
rotating feed screw that picks up the polymer and advances it into and along the barrel. Most
of the extrusion screws consist of three zones:
• Feed zone - 1 to 5 diameters long.
• Transition zone - ½ to 9 diameters long.
• Metering or pump zone - to complete the length.
The feed zone picks up the resin under the hopper and moves it into the externally
heated barrel to begin melting. The transition zone compresses the material, eliminating air
pockets and establishing a solid bed of unmelted pellets or powder with melt filling all voids.
The conversion of the mechanical energy of the drive to heat occurs to a great extent in this
section, an important source of melting energy. The metering or pumping section of the screw
generates the pressure needed to force the polymer through the die system. In the process, the
rest of the polymer is melted and refined into a homogeneous mass. The gearboxes supplied
by extruder manufacturers may be horizontal or vertical, cast iron or welded. They may have
helical, herringbone or worm gears.
4. RAW MATERIALS
The main raw material required is compounded PVC resin. Presently both PVC &
Polyethylene plastics raw materials are indigenously manufactured. Other compounding
materials like plasticizers, stabilizers, lubricants and fillers are also manufactured in India. No
problem is envisaged for procurement of PVC resin and the other required compounding
materials. The raw materials required [2] are as follows:
[A] or [X1] PVC resin, [B] or [X2] DOP, [C] or [X3] Stabilizer, [D] or [X4]
Processing acids, [E] or [X5] Colourant, [F] or [X6] Filler, [G] or [X7] Other or Impact
modifiers.
[A] or [X1] PVC resin: PVC uncompounded resin, unlike some other thermoplastics
is not suitable for direct processing. To confer the required processing and end instability, it
is necessary to mix additives to the PVC resin. Following are some of the additives which are
generally used for the manufacture of rigid PVC pipes.
[B] or [X2] DOP or Plasticizers: Plasticizers provide PVC with special properties of
use similar to those of rubber. This naturally hard material becomes flexible and elastic
through plasticizers. At the same time, it retains its shape. The common plasticizer in Use is
DINP – Diisononyl phthalate, DIDP – Disodecyl phthalate, DBP – Dibutyl phthalate; BBP
– benzyl butyl phthalate. Reoplast, Paraplex etc.
[C] or [X3] Stabilizers: The use of stabilizers guarantees sufficient heat stability for
PVC during processing and protects the end product from change due to heat, UV-light, or
oxygen. Especially inorganic and organic salts of the metals calcium, zinc, barium, lead and
tin are added to PVC products [2]. The common stabilizers are lead, barium, cadmium, tib,
stearate etc.
[D] or [X4] Processing Acids or Lubricants: Widely used lubricants are Buty-Stearate,
Glycerol Moni - Stearate, Epoxidised Monoester of oleic acid, stearic acid etc.
[E] or [X5] Colourant or Pigments: There are three main reasons to use pigments in
PVC compounding: to achieve opacity in non-weatherable compounds, for UV protection in

97
weatherable compounds and to achieve a given color. Titanium dioxide is the major pigment
used. Other pigments are used in small amounts to achieve the desired color in combination
with the titanium dioxide.
[F] or [X6] Fillers: Fillers are also used for producing special quality product (e.g.
calcined clay is used to improve the electrical properties of cable compounds).
[G] or [X7] Other impact modifiers: Certain applications require higher impact
strength than PVC would demonstrate normally. Acrylic, chlorinated polyethylene (CPE),
methacrylate-butadiene-styrene (MBS), and acrylonitrile-butadiene-styrene (ABS) polymers
are normally used to modify impact strength of PVC. These polymers provide a shock
absorber when the PVC is heated to a high enough melt temperature 196(C (385(F) to fuse it.
At lower melt temperatures, the impact is lower than it would be without impact
modification. At this lower melt temperature, the impact modifier acts like a hole or stress
concentrator making the impact lower. Using the proper melt temperature will ensure that the
full properties of the impact modifier will be realized.
Before the extrusion operation PVC resin is to be compounded with plasticizers,
stabilizers, lubricants and fillers to improve processibility and improve the endure stability.
PVC resin is compounded with other ingredients in a high speed mixer. The compound resin
is fed to the double screw extruder where the inserts and die body for the required pipe
diameter are fitted. The PVC compounds are then passed through a heated chamber and they
get melted under the compression of the screw and temperature of the barrel. The marking on
the pipe is done at the time of extrusion.
5. PLANT OUTPUT
The production basis for a typical tiny unit would be as under [7]:
Working hours/day: 8 (1 shift), Working days in a year: 300, Annual Production capacity:
150 MT PVC Pipes as follows in Table: 1
Sr.No Dia of the pipe
(mm)
Production in
length (meter)
Weight per running
meter (Kgs)
Total production
(MT)
1 90 75000 1000 75
2 110 53571 1415 75
6. DATA COLLECTION
The annual production (in MT) data was collected from the six industries (PI1, PI2,
PI3, PI4, PI5, PI6) located in the area MIDC (Maharashtra Industrial Development
Corporation), Jalgaon is as follows in Table: 2
Pipe
Industries
Plant
Output
(MT)
A
[PVC
resin]
(MT)
B
[DOP]
(MT)
C
[STABILISER]
(MT)
D
[PROCESSING
ACID]
(MT)
E
[COLOURANT]
(MT)
F
[FILLER]
(MT)
G
[OTHER]
PI1 80 200 10 5 4 12 10 5
PI2 85 180 14 4 3 14 8 4
PI3 90 220 16 6 5 10 6 6
PI4 95 160 9 5 5 13 5 5
PI5 85 210 15 6 6 15 4 4
PI6 100 230 16 8 8 16 4 4

98
7. FORMULATION OF MATHEMATICAL MODEL
It is quite clear that these individual factors will have different influence and
importance. Thus to evaluate the extent of influence of these factors on production output we
consider an exponential model [3] for plant output as follows.
Production output (PO) = K x [A]a
[B]b
[C]c
[D]d
[E]e
[F]f [G]g
----------------- (1)
Where, K=constant of proportionality, a, b, c, d, e, f and g are indices of factors A, B,C ,D,E,
F and G. The factor indices here shall demonstrate their influence on the respective factors A,
B, C, D, E, F and G. The equation (1) can be written in simple first order form by taking the
logarithm of both sides of the equation. Thus the equation becomes,
Log10 [Production output] = log10 K +a log10 A+ b log10 B+ c log10 C+ d log10 D + e log10 E+
f log10 F + g log10 G
The mathematical values of A, B, C, D, E, F and G represents the existing status of
the factor in the industry under study.
8. EXAMINATION
Questionnaire was prepared for assessing the role of factors and their influence on
effectiveness. The questionnaire and weightage design[3] was arrived at consultation with the
experts. This exercise led to following weightages.
WA = 0.16, WB = 0.14, WC = 0.19, WD = 0.14, WE = 0.13, WF = 0.13, WF = 0.11, Such
that WA + WB + WC + ……..=1
9. DATA ANALYSIS
Data collected is tabulated below in Table: 3
Pipe
Industries
Plant
Output
(MT)
A or
X1
[PVC
resin]
(MT)
B or
X2
[DOP]
(MT)
C or X3
[STABILISER]
(MT)
D or X4
[PROCESSING
ACID]
(MT)
E or X5
[COLOURANT]
(MT)
F or X6
[FILLER]
(MT)
G or X7
[OTHER]
(MT)
PI1 80 200 10 5 4 12 10 5
PI2 85 180 14 4 3 14 8 4
PI3 90 220 16 6 5 10 6 6
PI4 95 160 9 5 5 13 5 5
PI5 85 210 15 6 6 15 4 4
PI6 100 230 16 8 8 16 4 4
Weightages 0.16 0.14 0.19 0.14 0.13 0.13 0.11
The weighted values for the data set are given below in Table: 4
Pipe
Industries
Plant
Output
(MT)
A or X1
[PVC
resin]
(MT)
B or
X2
[DOP]
(MT)
C or X3
[STABILISER]
(MT)
D or X4
[PROCESSING
ACID]
(MT)
E or X5
[COLOURANT]
(MT)
F or X6
[FILLER]
(MT)
G or X7
[OTHER]
(MT)
PI1 80 32 1.4 0.95 0.56 1.56 1.3 0.55
PI2 85 28.8 1.96 0.76 0.42 1.82 1.04 0.44
PI3 90 35.5 2.24 1.14 0.7 1.3 0.78 0.66
PI4 95 25.6 1.26 0.95 0.7 1.69 0.65 0.55
PI5 85 33.6 2.1 1.14 0.84 1.95 0.52 0.44
PI6 100 36.8 2.24 1.52 1.12 2.08 0.52 0.44

99
10. OBSERVATIONS FROM WEIGHTED VALUES
From the table - 4 of weighted values it is observed that the PVC resin is having
highest impact on the production output of the PVC pipes hence it is clear that it is very
important input material while DOP and Colourant has moderate impact hence they are
important and stabilizer, processing acids, fillers and other material if any, having less or
poor impact on total production output of the PVC pipes, hence they are suppose to be less
important material as compare to others.
11. CONCLUSION
In this paper we have briefly examined the various factors which affect the production
output of PVC pipe extrusion process and have categorized them into seven major heads. A
field data based mathematical model has been evolved and a data were collected for it’s
further calculation. The data were examined by applying weighted value technique and thus
the importance of every factor affecting the production output of PVC pipe extrusion process
determined.
12. REFERENCES
[1] D.J. Van Zuilichem, W. Stolp, “Engineering Aspects of Single- and Twin-screw
Extrusion-cooking of Biopolymers”, Journal of Food Engineering 2, (1983), p.p 157-l 75
[2] Erdem Selver, “Extrusion and Properties of Nanoclay Added Composite Polypropylene
Monofilaments”, Auburn University Journal, Auburn, Alabama, (2010)
[3] Sahu Anil R, Dr.Shrivastava R.L, Dr.Shrivastava R R, “Key Factors affecting the
effectiveness of technical education – An Indian perspective”, proceedings of the world
congress Engineering, London, Vol II, (2008)
[4] PVCplus Kommunikations GmbHAm Hofgarten 1-253113 Bonn, Germany “Everything
about PVC from manufacturing to recycling” (2012)
[5] Oxyvinyls, “Ingredients Used in Rigid PVC Compounding”,technical report – 5, (2013)
[6] PW Eagle, “Technical Bulletin”, (2005).
[7] Dr. Narai Sailendra, “Profiles of SSI Projects”, Vol.I, Small Industries Development Bank
of India (SIDBI), Lucknow (2009).
[8] R. S. Hingole and Dr. V. M. Nandedkar, “The Need of Expert System for Forming
Analysis of Extrusion Process”, International Journal of Mechanical Engineering &
Technology (IJMET), Volume 1, Issue 1, 2010, pp. 248 - 252, ISSN Print: 0976 – 6340,
ISSN Online: 0976 – 6359.
[8] Boby K George and Dr. Shouri P.V., “Performance Measurement Frame Work
Development in Manufacturing Industries by the Application of Theory of Constraints”,
International Journal of Mechanical Engineering & Technology (IJMET), Volume 3, Issue 1,
2012, pp. 14 - 23, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359.

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Formulation of field databased model a case study at pvc pipe manu