sheet metal division word
TRANSCRIPT
AMARA RAJA GROUP OF COMPANIES
(MANGAL INDUSTRIES LIMITED)
AN INTERNSHIP REPORT
ON
STUDY OF MANUFACTURING PROCESS OF
CABINETS, TRAYS
UNDER GUDIENCE OF
Mr.P.SURESH
(Sr.Engineer, Production)
And
MR. MALLIKHARJUN RAO
(Sr.Supervisor, Machine Section)
BY
K.ROOPESH
B.TECH [MECHANICAL]
VIGNAN’S UNIVERSITY
1
ABSTRACT:
Today the major part of Transportation is by. This Automobile requires batteries
for charging. Not only automobiles, today many of the industries, hospitals, colleges, and
shops, many household and engineering applications require the use of batteries.
Keeping this importance on view, on the part of our mini project we visited Amara Raja
Company located at Karkambadi in Tirupati which manufactures industrial as well as
automotive batteries.
The report mainly deals with design process of sheet metal, various types of
processes in manufacturing the sheet metal at Mangal Industries Limited. The study and
process design of sheet metal helps us to provide a proper safety for the equipment.
Sheet metal is one of the fundamental forms used in metalworking, and can be cut and
bent into a variety of different shapes. Sheet metal has wide applications in Car bodies,
airplane wings, transformers and electric machines. Present work deals with the
integrated design and the manufacturing process of the sheet metal parts.
2
CONTENT
1. INTRODUCTION
2. PROCESS IN SHEET METAL DIVISION
3. TURRENT PUNCH PRESS
4. PRESS BRAKE
5. POWER PRESS
6. SHEARING MACHINE,TAPPING,SAWING
7. MANUAL MIG WELDING
8. ROBOTIC ARC WELDINIG
9. PRETREATMENT PROCESS
10. POWDER COATING PROCESS
3
INTRODUCTION
Mangal Industries Ltd, sheet metal division is a well know Manufacture of advanced sheet
metal products. To produce sheet metal products they follow different types of processes
like punching, bending, fabrication and powder coating.
Mangal industries will deal with various products like battery storage racks,
Cabinets, and home inverter. Major parts deal with ARBL as a battery storage rack about
60 to 70 % respectively. Large varieties of products are manufactured in trays fabrication
and most Cabinets are one of the models among them.
Cabinets are the main important product of mangal industries ltd. It is prepared by the
orders followed by the various companies. The main customer of cabinets is Amara raja
power systems ltd. Cabinets are prepared by different sheet thickness and different sheet
materials. It follows complete one cycle from raw material to final assembly.
Mangal industries Limited:
Mangal industries Limited, is a an Amara raja group company ,engaged in
manufacturing of sheet metal , pressed parts ,fasteners , automotive plastic components
and other battery related small parts. Mangal precision products -1 have been dedicatedly
established for Sheet metals only. Remaining components are manufactured at Mangal
industries Limited.
Mangal industries Limited brought technology and machinery from
NEDSHEROEF, Belgium, and a renowned manufacturer of cold forging machinery in the
world and completed all the product validation with technological support.
Mangal industry products:
Mangal industries Limited was incorporated in 1990 for manufacture of MS
Cabinets, trays, and racks for batteries, UPS, Battery Chargers, Inverters, etc. and to
manufacture small battery parts. It is having all the sheet metal processing machinery
starting from sheet cutting to final painting with punching, bending, welding,
phosphating(pre-treatment process), and powder coating processes. The plant is located
at Tirupati and is registered as an ancillary unit to ARBL and ARPSL. The operations of
the company are brisk and satisfactory.
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The Mangal Industries Limited-Sheet Metal Division consists of mainly four sections as
follows
1. Machine section
2. Fabrication section
3. Pretreatment
4. Painting section
5. Finishing and dispatch
Products
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PROCESS IN SHEET METAL DIVISION
Different type of process in sheet metal division:-
1. CAD drawing.
2. CNC Programming.
3. CNC Turret Punching.
4. Shearing.
5. CNC Bending.
6. Pressing.
7. Tapping.
8. Power hack saw cutting.
9. Manual MIG welding.
10. Robotic arm MIG welding.
11. Spot welding.
12. Stud welding.
13. Sanding.
14. Pre-Treatment (phosphating).
15. Powder Coating (Automatic powder Coating& Manual powder coating).
16. Final Assembly.
1. CAD DRAWING
CAD is most commonly associated with the use of an interactive computer graphics
system, referred to as a CAD system. It is the application of computers and graphics
software to aid or enhance the product design from conceptualization to documentation.
There are several good reasons for using a CAD system to support the engineering
design function:
1. To increase the productivity.
2. To improve the quality of the design.
3. To uniform design standards.
4. To create a manufacturing data base.
5. To eliminate inaccuracies caused by hand-copying of drawings and inconsistency
between drawings.
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CNC PROGRAMING
PROGRAMMING PROCEDURE
1. Determining punching method.
2. Determining positions of work clamps.
3. Checking tools and station numbers.
4. Determining punching sequence.
5. Calculating coordinates -Calculate the coordinates in units of 0.01 mm or 0.001"
(inches).
6. Checking-Check the work clamp positions, punching sequence and coordinates.
The software used for transfer machine program is
AP 100- for Amada EM 2510 NT
The program is transferred from control unit to the CNC TPP through LAN connection.
The drawing is converted into coding by the software mentioned above. Each CNC TPP
uses different software. A separate computer controls each TPP, which is in control unit.
BASIC FUNCTION CODES
G○○ "G" function (Preparatory function)
M○○ "M" function (Miscellaneous function)
T "T" function (Tool function)
N○○○○○ Sequence number
O○○○○ Program number
Programming responsibities.
Produce accurate programs.
Take production lots into considerations.
Designate turret layout.
Designate work holders.
Select appropriate table speed that can stabilize machining.
Notify press operators of any special operations.
Understand tool usage.
Make product sheet layout.
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CNC TURRET PUNCHING (TURRET PUNCH PRESS)
Punching is the process of producing holes of any desired shape in the part or sheet using
suitable punch and die of press tool in press machine.
Formula for cutting
F =StL
S=Shear strength of the sheet metal, KN.
t =stock thickness, m
L = length of the cut edge, mm
.
How Turret Punch Press work?
The press motor drives the flywheel, the flywheel torque is transmitted to the crank via
the hydraulic clutch-brake unit, and the rotating force of the crank drives the striker to hit
the punch.
A single AC servo motor, along with a heavy duty precision ball screw and link assembly
, which is mounted in the bridge frame to achieve hit rates of up to 390 hpm on 1" centers
and up to 900 hpm marking speeds.
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Sheet thickness:
The sheet thickness is denoted by the alphabet G. The following data gives the thickness
in mm with various G values. Acceptable tolerance limit is +/- 0.15
20G 1.00 mm
18G 1.2 mm
16G 1.6 mm
14G 2.00 mm
12G 2.50 mm
10G 3.15 mm
8G 4 mm
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Specification of Turret Punch Press
Button x & y axis m/min
T-axis rpm
C-axis rpm
F1 100/80 30 60
F2 75/60 30 60
F3 50/40 15 30
F4 25/20 15 30
Manual 5.2 3 -
Model : EM2510NT Nominal Press Capacity : 200 KN or 20MT Tool Stations : 45 (Auto Index Stations: 4 No's (G & H)) Max., Sheet Size : 1270 x 5000 mm. Max., Sheet Thk : 3.2 mm X (Carriage) – Axis travel : 2500 mm Y (Table) – Axis travel : 1270 mm Punching accuracy : 0.07 mm Turret speed : 30 rpm Max., Press Stroke Length : 37 mm Max., Feed Speed X-axis : 100 m/min Max., Feed Speed Y-axis : 80 m/min Max., Sheet Mass : 50 kg at F1 Speed Max., Sheet Mass : 150 kg at F4Speed Power : 27 KVA Air Supply : 250 lit/min Operating Air Pressure : 0.5mpa Strokes/min : 1 mm pitch (5mm stroke) – 780 hpm
X-axis: 25.4 mm pitch (5mm stroke) – 500 hpmY-axis: 25.4 mm pitch (5mm stroke) – 330 hpm
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Turret Station Arrangement
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Tooling of Turret Punch Press
PUNCH AND DIE CLEARENCE
Thickness
(mm)
Recommendable Clearance (mm)
Mild Steel Aluminum Steel Stainless Steel
0.8 0.15~0.2 0.15 0.2~0.24
1.0 0.2~0.25 0.15~0.2 0.25~0.3
1.5 0.3~0.375 0.225~0.4 0.375~0.45
2.0 0.4~0.5 0.3~0.4 0.5~0.6
2.5 0.5~0.625 0.375~0.5 0.625~0.75
3.0 0.6~0.75 0.45~0.6 0.75~0.9
3.2 0.65~0.8 0.48~0.64 0.8~0.96
3.5 0.7~0.875 0.525~0.7 0.875~1.05
4.0 0.8~1.0 0.6~0.8 1.0~1.2
4.5 0.9~1.125 0.675~0.9 1.2~1.35
5.0 1.0~1.25 0.75~1.0 -
5.5 1.1~1.375 0.825~1.1 -
6.0 1.2~1.5 0.9~1.2 -
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CNC Bending (PRESS BRAKE)
Bending of sheet metal is a common and vital process in manufacturing industry.
Sheet metal bending is the plastic deformation of the work over an axis, creating a change
in the part's geometry. Similar to other metal forming processes, bending changes the
shape of the work piece, while the volume of material will remain the same. In some cases
bending may produce a small change in sheet thickness. For most operations, however,
bending will produce essentially no change in the thickness of the sheet metal. In addition
to creating a desired geometric form, bending is also used to impart strength and stiffness
to sheet metal, to change a part's moment of inertia, for cosmetic appearance and to
eliminate sharp edges.
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Press brakes are machines used to bend sheet metal. To do so, a bottom tool is
mounted on a lower, stationary beam and a top tool is mounted on a moving upper
beam. The sheet metal is placed between the two tools and the top tool is pressed
down .The force exerted between the two beams is transferred through a frame.
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How press brake works?
This machine is a hydraulic down-acting press brake controlled by a hybrid drive system.
The OPENING and CLOSING foot pedals are pressed to open and close the ram. The
punches are installed on the upper beam, and the dies are installed on the lower beam.
The worksheet is laid over the dies, supported by hand, and bent by closing the ram onto
the punches. The auxiliary cylinders installed at the center of the lower beam prevent the
worksheet from drooping at the middle when bent over a long length. The bend angle of
the worksheet depends on the clearance between the punches and dies .The ram is
opened and closed by the main cylinders installed at the left and right sides. The main
cylinders can be controlled independently to tilt the ram. This tilting function allows the
difference in the bend angle between the left and right sides of the worksheet to be
compensated for and the worksheet to be offset bent. The worksheet can also be pushed
against the stoppers of the back gauge to determine its bend line. The machine can be
operated from the pendant control box.
Coordinate system of axes
D1 axis: Axis along which the left main cylinder of the lower beam moves up and down
D2 axis: Axis along which the right main cylinder of the lower beam moves up and down
L1 axis: Axis along which the back gauge moves back and forth on the left ball screw
L2 axis: Axis along which the back gauge moves back and forth on the right ball screw
Y1 axis: Axis along which the left back gauge moves left and right
Y2 axis: Axis along which the right back gauge moves left and right
Z axis: Axis along which the back gauge moves up and down
CC value: Pressure of the auxiliary cylinders in the lower beam
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Specification of Press Brake (RG 100)
Capacity 100 tons
Table Length 3000 mm
Maximum Bending Length 3100 mm
Distance b/w uprights 2550 mm
Throat Depth 400 mm
Length of stroke 100 mm
Open height 370 mm
Motor 400/460,230 volts
Power required 10.2 kv a
Hydraulic oil Reservoir 65 liters
Mass of Machine 6400 kg
How to Calculate Bend Allowance for Press Brake?
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Formulae
Bend Allowance = Angle * (PI / 180) * (Radius + K-factor * Thickness)
Bend Compensation = Bend Allowance – (2 * Set Back)
Inside Set Back = tan (Angle / 2) * Radius
Outside Set Back = tan (Angle / 2) * (Radius + Thickness)
Where,
Bend Allowance – The length of the arc through the bend area at the neutral axis.
Bend Angle – The included angle of the arc formed by the bending operation.
Bend Compensation – The amount by which the material is stretched or compressed by
the bending operation. All stretch or compression is assumed to occur in the bend area.
Bend Lines – The straight lines on the inside and outside surfaces of the material where
the flange boundary meets the bend area.
Inside Bend Radius – The radius of the arc on the inside surface of the bend area.
K-factor – Defines the location of the neutral axis. It is measured as the distance from
the inside of the material to the neutral axis divided by the material thickness.
Mold Lines – For bends of less than 180 degrees, the mold lines are the straight lines
where the surfaces of the flange bounding the bend area intersect. This occurs on both
the inside and outside surfaces of the bend.
Neutral Axis – Looking at the cross section of the bend, the neutral axis is the theoretical
location at which the material is neither compressed nor stretched.
Set Back - For bends of less than 180 degrees, the set back is the distance from the
bend lines to the mold line.
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Different Types of Bends
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PRESSING OR STAMPING (POWER PRESS)
Power Press: Power press are used for producing large quantities of articles quickly,
accurately and economically from the cold working of mild steel and other ductile
materials. The components produced range over an extremely wide field and are used
throughout industry. Sometimes the pressings may be complicated and more than one
pressing operation may be required. Now-a-days practice is to produce most of the sheet
parts of any shape by using specially designed press tools and other combination of
operations. For economical production of quantities of pressings, consideration has to be
given to type the rate of production, the cost of the press tools to be employed and the
expenditure involved in setting them. It is also necessary to plan the operations to reduce
scrap material to a minimum and to use waste material for other smaller pressings.
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Mechanical Press
Mechanical presses is the clutch used to transmit the motor and flywheel torque to the
gear shaft and, after clutch release, the brake which is used to decelerate the slide, the
top die and the gear. Particularly when working in single-stroke mode, the masses in
translational or rotational motion must be brought to a standstill after every stroke within
an extremely short time: 200 to 300ms for large-panel presses and 100 to 150 ms in
universal presses. Conversely, after engaging the clutch, the same masses must be
accelerated from zero to operating speed. Braking is generated mechanically by spring
power. The clutch torque is calculated from the nominal press force and the required
working distance, generally 13 to 25 mm above bottom dead center.
Pneumatic single-disk clutch and brake combinations with minimum rotating masses.
Pneumatic control systems with safety valves and damping devices are reasonable in
cost and generally comply with requirements. One of the problems of pneumatic systems,
however, is the limited switching frequency of single-stroke presses and the
environmental damage caused by wear to the clutch and brake.
Clutch-brake disk
Eccentric Shaft
Planetary gears
Fly wheel
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.
Pressing Force
The force required to be exerted by the punch in order to shear out the blank from the
stock can be estimated from the actual shear area and the shear strength of the material.
P = L t Where P = punching force, N = shear strength, MPa
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Specification of Power Press (AIDA-NCI -1100)
Capacity 1100 Kn
Slide stroke 180 mm
Stroke per minute 35-65 spm
Die height 350 mm
Slide Adjustment 90 mm
Slide Area 630x520 mm
Bolster Area 1070x680 mm
Main motor 75 kn
Required air press 0.5 Mpa
Maximum upper Die Height 550kg
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SHEARING MACHINE
Shearing operations are accomplished by the action of two blades, one fixed and one
moving vertically, meeting progressively from one side of the material to the other much
like ordinary hand shears. The angular alignment of the blades is called the rake. Also to
be considered is the blade or knife clearance to each other. Both rake and clearance are
a function of the type and thickness of the material to be cut.
The typical shear consists of:
• A fixed bed to which one blade is attached
• A vertically moving crosshead which mounts on the upper blade
• A series of hold-down pins or feet which hold the material in place while the cutting
occurs
• A gaging system, either front, back, or squaring arm, to produce specific work piece
sizes
Shears may be operated manually, mechanically, hydraulically, or pneumatically. They
can also be classified by their design. “Gap” and “gapless” shears are defined by their
side frames and the maximum size sheet they can handle. “Right angle” shears have two
blades set at a 90 degree angle to each other and will cut simultaneously in two directions.
“CNC” shears are programmable to cut various sizes by automatically feeding material
into the blades.
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Tapping
This operation is performed by a tap and is used to provide internal screw threads on an
existing hole.
Sawing (cutting)
Sawing is a process in which a narrow slit is cut into the work by a tool consisting of a
series of narrowly spaced teeth. Sawing is normally used to separate a work part into two
pieces, or to cut off an unwanted portion of a part. These operations are often referred to
as cutoff operations. Since many factories require cutoff operations at some point in the
production sequence, sawing is an important manufacturing process.
Hacksawing involves a linear reciprocating motion of the saw against the work. This
method of sawing is often used in cutoff operations. Cutting is accomplished only on the
forward stroke of the saw blade. Because of this intermittent cutting action, hacksawing
is inherently less efficient than the other sawing methods, both of which are continuous.
The hacksaw blade is a thin straight tool with cutting teeth on one edge. Hacksawing can
be done either manually or with a power hacksaw. Power hacksaw provides a drive
mechanism to operate the saw blade at a desired speed; it also applies a given feed rate
or sawing pressure.
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Manual Welding
Joining metals through heating them to a molten state and fusing them together. Classification of welding
25
MIG (metal inter gas) Welding Process MIG welding process that melts and joins metals by heating them with an arc established
between a continuously fed filler wire electrode and the metals. Shielding of the arc and the
molten weld pool is often obtained by using inert gases such as argon and Helium. Argon,
helium, and their mixtures are used for nonferrous metals as well as Stainless and alloy
steels. The arc energy is less uniformly dispersed in an Ar arc than in a He arc because
of the lower thermal conductivity of Ar.
Specification of MIG welding machine (AUTO K 400)
Supply voltage ,phase ,frequency 415+10%,3,50HZ AC
Maximum input current 31 Amps
Maximum rating 20.7 kva
Current range DC 600 A-400 A
Maximum output at 60%duty cycle 400 Amps
Maximum output at 100%duty cycle 310 Amps
Open current circuit voltage 55 volts
26
Robotic Arm MIG welding
Automated welding that is composed by robots called “Welding Robots”. The used
mechanism 6-axes vertical Articulated, 3 dimensional welding can be done.
27
The Robotic Arc Welding Process Parameters
To design a welding robotic system the first step is to identify the process related
parameters, i.e., the parameters that should be controlled in a way to obtain the desired
quality, also defined by a set of accepted characteristics. The process related input
parameters can be classified into three different categories:
1. Primary inputs: Variables that can be modified on-line during the welding process.
Taking as example the MIG process, the primary welding parameters are the voltage, the
wire feed rate, and the torch speed. Technically, the voltage and the wire feed rate are
analog signals commanded to the welding power source, and generated from the robot
controller or process PLC. The torch speed is the desired speed
Commanded to the robot TCP for coordinated motion.
2. Secondary inputs: Variables defined when the process is selected and before any
welding service. Using again as example the MIG process those parameters include the
type or composition of the shielding gas, the flow of gas during the process, the torch
angle, and the type and size of the wire to use.
3. Fixed inputs: Parameters that are fixed and cannot be changed by the user. These
parameters are usually an imposition of the selected welding process, of the current
welding procedure or of the physical setup. Parameters of this type include the joint
geometry, plate thickness, physical properties of the plate metal, etc.
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Specification of arc welding robot
Axes-6
Payload-6kg
Height reach- 1368mm
Repeatability- +0.1 to -0.1mm
Robot mass-290kg
Robot motion Speed- J1-120o/s J4-360o/s
J2-120o/s J5-360o/s
J3-120o/S J6-450o/s
Robot motion range- J1 -165o to +165o J4 -190o to +190o
J2 +135o to -75o J5-140 o to +140o
J3 +150 oto-149o J6 -320o to +320 o
Control unit
Movement of the torch is determined .Reference points (knot points) and welding
parameters on these reference points are determined.
The control unit controls these guidance Control unit determines the rotational
speed of joint (linkage) motors, speed and moments according to the data obtained
from positional sensors.
Number of axes and additional units (positioner, slider and secondary
robots).Control units are able to handle up to 15-axes.
Optical Sensors Optical sensors use the following basic principle for detecting the weld joint during arc
welding; (i) a laser beam that is projected in a scanning motion across the seam and (ii)
a CCD-array that is used to measure features of the weld joint in combination with a laser
stripe.
29
Variations of this method are in use and, as an example, the laser stripe may not be a
linear line on the weld joint but circular instead. In such a case, the sensor is more flexible
to detect weld joints in corners from one location of the torch, or point of view of the
sensor. To measure the distance, the method of triangulation is used which is of great
importance in welding.
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PRE-TREATMENT PROCESS Pre-treatment process in which the surface of the component to be painted is chemically
prepared the painting operation. Metallic component can be frees from impurities with
proper pretreatment, Using degreasing and derusting solutions, coated with a protective
layer of phosphates and passivized for lasting effects.
Process followed:
1. Pre-Degreasing.
2. Degreasing.
3. Water rinsing.
4. Derusting.
5. Water rinsing.
6. Activation.
7. Phosphating.
8. Water rising.
9. Passivation.
Degreasing:
During the manufacturing of any metal based on component there is addition of oil and
light grease. This addition oil is been done mainly to get a smooth and frictionless method
of mechanical procedure on the component been manufactured. This stage of
pretreatment process helps to remove the oil stains from the machined or manufactured
component. To discover a surface finishing free from oil these tanks filled with solution
play a very important role.
(Tme:5 minutes;temperature:65-75oc;Pointage:33-37;Chemical required: Metaclean922)
Derusting:
Before manufacturing of any metallic component or product, the raw material to be used
is normally stocked by large and medium companies. Due to laying of material one above
other and not been used for long duration stains of rust are been observed on the metal
surface .also after the product is manufactured completely and before painting there is a
stock as per the requirement of different colors .thus air and moisture in air tends to create
rusty and corrosive surface on the product making it unsuitable surface finishing for
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painting .Derusting stage of the pretreatment process is bath of chemical to remove the
rust and make it free from corrosive areas, for a better surface finishing (Time:15
minutes;;Pointage:20-25;Chemical:Derustine125)
Phosphating:
Phosphating stage can be use full only when the stage are thoroughly used. Once the
surface finishing or surface treatment of the product is done, the phosphate liquid forms
a phosphate coat on metal surface ,which turns becomes an integral part of the product.
This phosphate coat developed on metal surface make the surface more adaptive to the
paint to be sprayed on it.
Phosphating may be carried out at temperatures ranging from 30-99 °C and processing
time can be varied from a few seconds to several minutes. Suitable choice of these
parameters is determined by factors such as nature of the metal to be coated, thickness
and weight of the coating required and bath composition.
(Time:5 minutes;temperature:50-55oc;Pointage:2630;Chemical:Phosbond,Accelarator)
Water rising:
The rinsing step followed by cleaning plays a vital role in the phosphating sequence.
Rinsing prevents the drag out of chemicals used in the earlier cleaning that may
contaminate the subsequent stages.
(Time: 1 minute; PH: 7-10)
Rinsing after phosphating:
The surface that has been subjected to phosphating should be thoroughly rinsed with
deionized water to remove any acid residue, soluble salts and non-adherent particles
present on it which would otherwise promote blistering of paint films used for finishing.
(Time: 1 minute; PH: 4-7)
Activation: This gives more compact and uniform coating of zinc phosphate. This step can be omitted
for iron phosphate process.
Passivation:
The passivation of phosphate surface with chromic ac id solution is very important step
in improving the overall performance of paint film. Chromic acid dissolves any trace of
water soluble salts in the pores of phosphating coating. It form a thin passive oxide film.
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Surface Powder Coating
In powder coating, the finely ground particles of pigment and resin are electrostatically
charged and sprayed onto a metal part. The coating process can be done manually or
automatically with a wide variety of equipment available to small and large end users. The
parts to be coated are grounded neutral so that the charged particles projected at them
adhere to the parts and are held there until melted and fused into a smooth coating in the
curing ovens. The result is a uniform, durable, high-quality finish.
THERMOPLASTIC POWDER COATINGS A thermoplastic powder coating melts and flows on the application of heat, but continues
to have the same chemical composition when it solidifies on cooling. Thermoplastic
powder coatings are based on thermoplastic resins of high molecular weight. The
properties of these coatings depend on the basic properties of the resin. These tough and
resistant resins tend to be difficult, as well as expensive, to be ground into the very fine
particles necessary for the spray application and fusing of thin films.
One of the most significant advantages of powder coating is that it does not require
special air makeup to the coating booth. Since powder contains no compounds that are
volatile at room temperature, air makeup for the booth can be recirculated to the plant
Economic advantages resulting from higher operating efficiencies are many and varied,
depending upon the particular operation. The most significant advantage is the material
usage efficiency. Fluidized bed operations are inherently 100% efficient, although some
loss may result from such items as drag out and excess film. Electrostatic spray
operations are usually considered to be between 50 and 80% efficient upon first use of
the powder. That is, from 20 to 50 of the material is over sprayed and, if collected, can be
reused as satisfactory powder. Since over sprayed powder can be reclaimed during the
application process and therefore reused, overall material utilization in the range of 95 to
98% can be achieved. By comparison, liquid spray coating systems can achieve material
usage efficiencies only in the range of 20 to 90%. With electro coating, 98 to 99%
efficiency is possible.
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ELECTROSTATIC POWDER SPRAY COATING To apply powder coating materials with the electrostatic powder spray process, five basic
pieces of equipment are needed:
Powder feeder unit.
Electrostatic powder spray gun.
Electrostatic voltage source.
Powder recovery unit.
Spray booth.
In the operation of an electrostatic powder spray system, powder is siphoned, or pumped,
from a feeder unit through a powder feed hose to the spray gun(s). Spray guns direct the
powder toward the part in the form of a diffused cloud. Propelling force is provided both
by air that transports powder from the feeder unit to the spray gun, and by the electrostatic
charge imparted to the powder at the gun. Electrostatic voltage is supplied to the spray
gun by a source designed to transmit high-voltage, low-amperage electrical power to an
electrode(s) attached to the spray gun. As the diffused, electrostatically charged powder
cloud nears the grounded part, an electrical field of attraction is created, drawing the
powder particles to the part and creating a layer of powder. Overspray-or powder not
adhering to the part-is collected for re-use or disposal. In the collector unit, powder is
separated from the conveying airflow. Collected powder is then automatically or manually
recycled back to the feeder unit to be resprayed.
Powder Feeder Unit
Powder is supplied to the spray gun from the powder feeder unit. Usually powder material
stored in this unit is either fluidized or gravity-fed to a pumping device for transport to the
spray gun .Newly developed feed systems can pump powder directly from the storage
box. The pumping device usually operates as a venturi, where compressed or forced
airflow passes through the pump, creating a siphoning effect and drawing powder from
the feed hopper into powder hoses or feed tubes. Air is generally used to separate powder
particles for easier transporting and charging capabilities. Volume and velocity of the
powder flow can be adjusted.
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Fluidized powder hopper
The fluidized powder in the powder hopper is sucked into the injector b means of the
conveying air (1) .The powder/air mixture reaches the powder gun through the powder
hose (2). The powder is electrostatic charged at the gun nozzle. In addition, an
electrostatic field is created between the gun nozzle and the grounded object. The
charged powder spray remains adhered to the surface of the object. The powder is
fluidized by air forced through a porous plastic plate from below. The powder acquires,
thereby, fluid-like characteristics the conveying air, supplementary air, and rinsing air are
set on the control unit
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How Powder gun works?
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High voltage generation
The control unit supplies a high-frequency low voltage signal of approx.10 V eff. This
voltage is fed through the gun cable (11) to the high voltage cascade (4) in the gun body.
In the high voltage cascade (4), the low voltage is high-transformed in a first step (c). This
primary high voltage is subsequently rectified and multiplied in the high voltage cascade
in a second step (d), until the required high voltage is obtained at the end (approx. 100
kV). The high voltage is now fed to the electrode (e) within the spray nozzle.
Circuit
In addition to the modulated low voltage needed for high voltage generation, there are
signal lines fed trough the gun cable. The control signals are used for monitoring gun
trigger status and gun remote control functions. The gun is released by a reed switch,
which is operated by a magnet in the trigger (17). The gun control unit switches on the
modulated low voltage, the powder transport and the rinsing air.
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Flat jet nozzle
The vented flat jet nozzle serves for the spraying and the charging of the powder. The
powder cloud obtains an oval spray pattern by the slot shaped opening. The powder is
charged by the central electrode. The high voltage, which is created in the gun cascade,
is conducted through the black contact ring of the nozzle holder to the central electrode.
In order to prevent powder from sintering on the electrode, compressed air is used during
the spray process. Therefore, the rinsing air is fed through the small hole in the black
contact ring of the nozzle holder, and into the electrode holder.
Round jet nozzle with vented deflector
The vented deflector is used, to give the powder stream emerging from the gun, a cloud
formation. The powder is charged by the central electrode. The high voltage, which is
created in the gun cascade, is conducted through the black contact ring of the nozzle
holder to the central electrode. Since powder can accumulate on the rear side of the
deflector, this must be rinsed with compressed air. The rinsing air is fed through the small
hole in the black contact ring of the nozzle holder into the electrode holder, and is driven
in such a way, that it flows over the surface of the deflector rear side.
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Gravity-assisted Booths with Cyclone Recovery
In this system, about 50% of the overspray falls back to the feed hopper by gravity. The
balance is collected through an extraction duct to the reclaim system. In this system, the
reclaim system is a virtually self-cleaning cyclone separator with reclaim recovery
efficiencies from 90 to 95%. The small fraction of powder remaining in the air stream, from
the cyclone, is separated in the final filter before the air is returned to the powder coating
room. The use of an efficient coating chamber with a self-cleaning cyclone allows an
unlimited number of color changes without duplication of filtering equipment. In gravity-
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assisted recovery booths, a portion of the overspray returns directly to the feed hopper
by gravity without entering the reclaim system. This minimizes the amount of reclaim
powder generated within the system.
Heating Process (Baking oven)
Post heating operations on a powder finishing line are perhaps the most critical. They are
used to melt, flow, and cure the powder applied to the part at ambient temperature, as
with the electrostatic spraying process. This application of heat has to be very carefully
controlled because temperature-fluidity characteristics of a particular powder are peculiar
to that powder. It is this relationship that determines how the flow of the material will take
place as the temperature is raised. Most materials cross link and become more viscous
with time at a given temperature. Final properties of the coating can be acquired only
uniformly over the part if all areas of the coating are treated in thermally equivalent
conditions. For this reason, the post heat ovens again must be of high quality and
equipped with adequate controls to ensure reproducibility.
The time required to bring powder deposited on the part to its cure temperature largely
depends on the mass of the part and the rate at which the part accepts heat using
convection heating. Large metal objects may require 30 minutes or more to reach the
desired cure temperature. Smaller parts can be brought to temperature much more
rapidly 4 to 8 minutes.
Inspection
Inspecting with Coat measure to check the thickness of powder coating.
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Specification for Powder coating
Oven Temperature 200+/-10oc
Conveyor speed 30-90 m/hr
Soaking time 15-20 minutes
Deflector size 14mm/16mm for interior surface
Electrode Voltage 60-90 kv
Powder flow 150-250 g/min(based on component)
Dry film thickness 65 microns -80 microns
Fluidization pressure 2-3 kg/cm2
Final assembly
After powder coating to the cabinet the final assembly is done by using suitable screws, nuts,
bolts, door locks, handles, washers, studs, eye bolt, knobs etc As shown in fig below.
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DISPATCH:
After final assembly the cabinet can dispatch with packing as shown in fig below.
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5’S-PRINCIPLE &OBSERVE THE 5’S IN COMPANY
INTRODUCTION:
The Amara raja group of companies follows the 5’S which encompasses various
aspects of productivity like storage ,filing ,space utilization ,cleanliness ,assembly line
management and standardization
5S is the name of a work place organization method that uses a list of five
Japanese words. They are
1. Seiri (Sort)
2. Seiton (Systematize)
3. Seiso (Shine)
4. Seiketsu (Standardize)
5. Shitsuke (Self-discipline)
1. Seiri (Sort):
Remove unnecessary items & dispose of them properly.
Make work easy by eliminating obstacles.
Provide no chance of being disturbed with unnecessary items.
Prevent accumulation of unnecessary items.
2.Seiton (Systematize):
Arrange necessary items in order so they can be easily picked for use.
Prevent loss waste of time.
Make it easy to find and pick up necessary items.
Ensure first-come-first –serve basis.
Make work flow smooth & easy.
Can also be translated as “set of order”.
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3. Seiso (Shine):
Clean your work place completely.
Use cleaning as inspection.
Prevent machinery & equipment deterioration.
Keep work place safe & easy to work.
Can also be translated as “sweep”.
4. Seiketsu (Standardize):
Maintain high standards of housekeeping & work place organization at all
times.
Maintain cleanliness & orderliness.
5. Shitsuke (Self-discipline):
To keep in working order.
Also translates to “self-discipline” meaning to do without being told.
5’S DIAGRAMS
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SAFETY WEARINGS :
SHOES EAR PLUGS
HAND GLOVES
GOGGLES
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CONCLUSION
Thankful to Amara raja group of
companies (Mangal Industries limited) for providing Internship program. I’m Happy to gain
knowledge past four months in here. I got good knowledge, about CNC machinery. I got
good communication and supervision skills. I’m very happy to have freedom and guide
lines by the officials in the MIL-SMD plant. And happy about the safety & 5’S system
provided by the company.
Finally, I thank full to the plant Engineer’s, in charges,
supervisors, employees and skill development officers for having good interaction and
supporting.
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Presented By,
K.Roopesh
121FA08026
B.Tech, Mechanical
Vignan’s University
Cell: +91 9052941152