PREFACE My industrial training report represents the outcomes of 22 weeks training period that I had spent at the Industrial Development Board of Ceylon as an Engineering trainee from 01 th of April 2010 to 17 th of August 2010. Report contains three chapters. Chapter one is dedicated to the Industrial Development Board current status strengths and weaknesses. Chapter two describes the training experience that I have gathered. My Training experience focuses on machinery, manufacturing processes and projects that I have taken part in. And the final chapter is the “conclusion”. This consists of summary of my overall training and comments on training establishment and my suggestions to improve the training given by Industrial Development Board. At the end of the report 10 annexes are attached and they contain the project reports and drawings done by my self Piyanka W.P.G.T (070367R) Department of Mechanical Engineering Faculty of Engineering University of Moratuwa
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PREFACE
My industrial training report represents the outcomes of 22 weeks training period that I had
spent at the Industrial Development Board of Ceylon as an Engineering trainee from 01 th of
April 2010 to 17thof August 2010.
Report contains three chapters. Chapter one is dedicated to the Industrial Development Board
current status strengths and weaknesses.
Chapter two describes the training experience that I have gathered. My Training experience
focuses on machinery, manufacturing processes and projects that I have taken part in.
And the final chapter is the “conclusion”. This consists of summary of my overall training
and comments on training establishment and my suggestions to improve the training given by
Industrial Development Board.
At the end of the report 10 annexes are attached and they contain the project reports and
drawings done by my self
i
Piyanka W.P.G.T (070367R)
Department of Mechanical Engineering
Faculty of Engineering
University of Moratuwa
ACKNOWLEGEMENT
I think I must grateful to the training division specially Mr.Gunawardhana and
Mr.Wijewikrama for tackle my training place problem, Department of Mechanical
Engineering and NITA for taking initiative to deliver us such a successful training period.
Also I thanks to the Industrial Development Board of Ceylon for taking me as an in plant
trainee.
I also want to express my heartiest gratitude to the Engineering Department of IDB Chief
Engineer Mr.Rathnamala, training coordinator Mr.Razool, Workshop Engineer Mr.Premasiri
and Technical Assistant Mr.Dissanayake, and all the machine operators and workers those
who spent their precious time for us.
I also wish to express my sincere gratitude to Mr.Ariyadasa Jayawardhana the Personal
Director for his kindly support and offering a payment for us to complete training at
Industrial Development Board successfully.
A word of big thanks must also go to my fellow colleague who trained with me at Industrial
Development Board for sharing his knowledge and time with my self.
Thank again you all for your generous support toward to myself.
More than all, it is the effort of my family, who made me what I am today. The blessing that
they gave me helped more than in one way to overcome the challenges that I faced during my
entire life. So a very special tribute must also go to my family, since I owe them for
everything they had done.
ii
Piyanka W.P.G.T (070367R)
Department of Mechanical Engineering
Faculty of Engineering
University of Moratuwa
Table of ContentsPREFACE................................................................................................................................................. i
ACKNOWLEGEMENT.............................................................................................................................. ii
List of Figure..........................................................................................................................................v
CHAPTER 1: INTRODUCTION TO TRAINING ESTABLISHMENT................................................................1
1.0.1. Mission of the IDB.........................................................................................................1
1.0.2. Structure of the Industrial Development Board.............................................................2
1.0.3. Act of Incorporation Set out the Object of the IDB As Follows:....................................3
Yet another major constraints faced by the rural and medium scale industrialist is the market
problem. In order to increase and establish the market share of the existing industries of the
SME sector and the potential entrepreneurs the following services are offerd by the marketing
division.
Marketing information
Managing and coordinating sale centers “Laknipayum” in Colombo and “Lakkam
trade center” at he head office katubadda.
Sub-contracting facilities
Organizing and conducting exhibition and trade Eras.
Provision of metal scrap to SMEs and medium light engineering industrialist.
10
TRAINING EXPERIENCE CHAPTER 2
CHAPTER 2: TRANING EXPERIENCE
My first week on Industrial Development Board I was assigned to mechanical workshop to
develop my knowledge on machines and machine processes and also to get hands on
experience of them. Basically mechanical workshop can divide into several sections. They
are lathe and milling, cutting, welding.
On the first day workshop engineer Mr.Premasiri assigned me under supervision of Technical
Assistant Mr.Dissanayake to get a good knowledge about manufacturing processes. Since
first week I spent my time in lathe and milling section to gain knowledge about lathe and
milling processes. Then I focused on Shaping Grinding and Welding operations.
First I started learning about milling machine with the help of machine operator. So there he
told me about basic components if a milling machine first. Then I observe those components
and recognized them very well (like lathe Bed, carriage or saddle, tool post, slide ways,
tailstock, chuck, spindle speed selector, and etc). Machine to machine the some of
components vary their positions and the availability.
Then he taught me the importance of those components. So I listed those components and
their importance as bellow.
2.1. MAIN LATHE COMPONENTS AND THEIR IMPORTANCE
2.1.1. The Lathe Bed Slide Way
It cast with a box-like cross section made of gray cast iron. It has two main functions.
To give the necessary stiffness for resisting the twisting and other stress, which occur in
practice and which if they strained the bed, would destroy the accuracy of lathe.
To ensure that the lathe-cutting tool moves accurately along a path that is parallel to the
machine spindle axis.
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TRAINING EXPERIENCE CHAPTER 2
Figure 2.01
2.1.2. The Carriage or Saddle
This is a flat-shaped casting, planed on its underside to fit the ways of the bed so that it may
slide along.
2.1.3. Headstock
Gear trains enable for driving spindle, feed shaft, lead screw and Gears for changing speeds
are housed in the headstock.
2.1.4. The Cross Slide
This provides,
Support for the compound slide.
Movement of the cutting tool at 90 Degrees to the rotating axis of the work piece.
Motion of the cross slide is obtain by a hand wheel, but on the majority of centre
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TRAINING EXPERIENCE CHAPTER 2
lathes a gear mechanism is fitted to give automatic traverse both towards the spindle
axis and away from it.
2.1.5. The Compound Slide
This is mounted on the cross slide and has two main functions.
To provide location and support for the tool post
To enable the tool to be place at angle to the axis of the spindle
Compound slide movement is obtained by using a hand wheel, no automatic traverse is
provided. The slide can be rotated about its mounting. The circular scale on the base indicates
the angle through which the slide has turned.
2.1.6. The Tool Post
This has two main functions.
Positioning the cutting tool
Securing the cutting in that position
There are two type of tool post,
Single tool post
Four way tool post
2.1.7. The Tailstock
This is the counter part of the headstock, and carries the right hand centre for supporting
work when turning centers. It is also used for supporting and feeding drills, reamers, etc.
when it is necessary to use these for drilling work held in the chuck.
Using the lateral adjustment screw can make sideways adjustment of the barrel. By this, the
centre of the barrel can move off centre with the headstock spindle centre. (Live centre)
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TRAINING EXPERIENCE CHAPTER 2
2.1.8. Steadies
For supporting long, slender work against the pressure of the cut, a steady is used. The fixed
or three jaw steady is clamped to the bed of the lathe and supports the bar, being turned by
means of three jaws set at 120 degrees with each other.
2.1.9. Work Holding Methods
The self - centering chuck (3 – Jaw Chuck)
The independent centering chuck (4 – Jaw Chuck)
Driving plate and centers
Face plate
The self-centering chuck (3 – Jaw Chuck)
This is the most convenient and most used method of work holding.
This can take wide range of diameters. When adjusting jaws move equal
amount light cuts should carry out, because the work may slip in the jaws. In addition, the
work should be firmly round to fix in this chuck.
The independent centering chuck (4 – Jaw Chuck)
Each jaw is individually adjust and moves along its own slot. One advantage of this four-jaw chuck is that work can be located in the centre to run true or off centre. One of the most useful applications of this type is to hold square or rectangular material positioned either centrally or off centre. Setting time is greatly increased when
compared to three-jaw chuck. However, for highly accurate work, this is the most suitable method.
Page 14
Figure 2.02
Figure 2.03
TRAINING EXPERIENCE CHAPTER 2
The faceplate
This is used to hold works, which can neither be turned on centers nor held in a chuck. It has
bolt slots for accommodating the necessary clamping bolts.
2.1.10. Tool Holding Method
I have mentioned some components and their importance above as I learned. Then I learned
about machine processes. Thereafter I was learned how to mount a work piece and how to
center it. First I found little bit difficult to mount the work piece correctly and also I learned
how to use surface gauge to center the work piece. Some times work piece is not reasonably
symmetrical.
When it wasn’t symmetrical I had to check the space between surface gauge and the work
piece surface opposite side of the chuck because I couldn’t see continuous equal space
between those two surfaces. I use 3-jaw and 4-jaw chucks to center work piece according to
the irregularities of the surfaces.
Once I mount the work piece I choose a cutting tool to mount on the tool post. When
choosing a cutting tool there are some factors to consider,
Cutting tool geometry varies with the type of work to be done.
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Figure 2.04
TRAINING EXPERIENCE CHAPTER 2
Facing tools are ground to provide clearance with a center.
Roughing tools have a small side relief angle to leave more material to support the
cutting edge during deep cuts.
Finishing tools have a more rounded nose to provide a finer finish. Round nose tools
are for lighter turning. They have no back or side rake to permit cutting in either
direction.
Left hand cutting tools are designed to cut best when traveling from left to right.
Aluminum is cut best by specially shaped cutting tools (not shown) that are used with
the cutting edge slightly above center to reduce chatter.
And also when installing a cutting tool there are some instructions to follow,
Lathe cutting tools are held by tool holders. To install a tool, first clean the holder,
and then tighten the bolts.
The tool post is secured to the compound with a T-bolt. The tool holder is secured to
the tool post using a quick release lever.
And for the positioning,
In order to move the cutting tool, the lathe saddle and cross slide can be moved by hand.
There are also power feeds for these axes. Procedures vary from machine to machine.
A third axis of motion is provided by the compound. The angle of the compound can be
adjusted to allow tapers to be cut at any desired angle. First, loosen the bolts securing the
compound to the saddle. Then rotate the compound to the desired angle referencing the dial
indicator at the base of the compound. Retighten the bolts. Now the tool can be hand fed
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Figure 2.05
TRAINING EXPERIENCE CHAPTER 2
along the desired angle. No power feed is available for the compound. If a fine finish is
required, use both hands to achieve a smoother feed rate.
The cross slide and compound have a micrometer dial to allow accurate positioning, but the
saddle doesn't. To position the saddle accurately, you may use a dial indicator mounted to the
saddle. The dial indicator presses against a stop (often a micrometer as shown in the clip
below).
Feed, speed, and depth of the cut,
Cutting speed is defined as the speed at which the work moves with respect to the tool
(usually measured in feet per minute). Feed rate is defined as the distance the tool travels
during one revolution of the part. Cutting speed and feed determines the surface finish, power
requirements, and material removal rate. The primary factor in choosing feed and speed is the
material to be cut. However, one should also consider material of the tool, rigidity of the
work piece, size and condition of the lathe, and depth of cut. For most Aluminum alloys, on a
roughing cut (.010 to .020 inches depth of cut) run at 600 fpm. On a finishing cut (.002
to .010 depth of cut) run at 1000 fpm. To calculate the proper spindle speed, divide the
desired cutting speed by the circumference of the work. Experiment with feed rates to
achieve the desired finish. In considering depth of cut, it's important to remember that for
each thousandth depth of cut, the work diameter is reduced by two thousandths.
2.1.11. Production of Chips
The production condition of chips in cutting work varies according to the quality of
work material, cutting speed, shape of tool, etc.
Cutting Resistance
In case of cutting work, bigger strength than the work acts. This strength is called
cutting resistance, and the strength, which is equal in size and opposite in direction to this
cutting resistance, acts on the work. This is called cutting force, having effects on the motive
power necessary for cutting, the life of tools, the finished surface and so on.
a) Three Force components
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TRAINING EXPERIENCE CHAPTER 2
i. Main force component
The force acts in the direction of pushing tools down, is biggest, and
consumes the majority of motive power.
ii. Back force component
Is the force pushing back tools from the work, becomes smaller, with bigger
rake angle, and may become minus force.
iii. Feed force component
Is the force to act pushing back tool opposite to feeding direction, and
various according to entering angle of tool.
b) Factors changing cutting resistance
i. Shape of tool tip
Cutting resistance is reduced lineally (up to about 30 Celsius Degree), according
to rake angle becoming larger. However, there is limit in enlarging rake angle, if
the strength of chip of cutting tool is considered.
ii. Cutting speed
In case of high-speed cutting, cutting resistance is reduced with the increase of
cutting speed.
iii. Entering angle of tool tip
Cutting resistance vary according to the entering angle of tool tip. Main force
component are increased, with the decrease of entering angle. Cutting resistance is
increased, with the increase (Cutting Volume) of out Depth x Feed (Cutting Area).
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TRAINING EXPERIENCE CHAPTER 2
iv. Cutting oil
With the use of adequate cutting oils and agents, friction is reduced by the
lubrication of cutting oil and cutting resistance is reduced.
v. Material
Hard material and tenacious material make cutting resistance bigger. The
quality of tool has no effect on cutting resistance almost.
2.2. BASIC LATHE MACHINE PROCESSES
Then I learned about basic machining processes like Turning, Facing, Parting, Drilling, and
Boring, Thread cutting.
2.2.1. Turning
The lathe can be used to
reduce the diameter of a
part to a desired
dimension. First, clamp
the part securely in a
lathe chuck. The part
should not extend more
that three times its diameter. Then install a roughing or finishing tool. If you're feeding the
saddle toward the headstock use a right-hand turning tool. Move the tool off the part by
backing the carriage up with the carriage hand wheel, then use the cross feed to set the
desired depth of cut. In the clip below, a finish cut is made using the power feed for a
smoother finish. Remember that for each thousandth depth of cut, the work diameter is
reduced by two thousandths.
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TRAINING EXPERIENCE CHAPTER 2
2.2.3. Facing
A lathe can be used to create a smooth, flat, face
very accurately perpendicular to the axis of a
cylindrical part. First, clamp the part securely in a
lathe chuck. Then, install a facing tool. Bring the
tool approximately into position, but slightly off
of the part. Always turn the spindle by hand
before turning it on. This ensures that no parts
interfere with the rotation of the spindle. Move
the tool outside the part and adjust the saddle to take the desired depth of cut. Then, feed the
tool across the face with the cross slide. The following clip shows a roughing cut being made;
about 50 thousandths are being removed in one pass. If a finer finish is required, take just a
few thousandths on the final cut and use the power feed. Be careful clearing the ribbon-like
chips; they are very sharp. Do not clear the chips while the spindle is turning. After facing,
there is a very sharp edge on the part. Break the edge with a file.
2.2.3. Parting
A parting tool is deeper and narrower than a
turning tool. It is designed for making narrow
grooves and for cutting off parts. When a parting
tool is installed, ensure that it hangs over the tool
holder enough that the holder will clear the work
piece (but no more than that). Ensure that the
parting tool is perpendicular to the axis of
rotation and that the tip is the same height as the
center of the part. A good way to do this is to
hold the tool against the face of the part. Set the height of the tool; lay it flat against the face
of the part, then lock the tool in place. When the cut is deep, the side of the part can rub
against sides of the groove, so it's especially important to apply cutting fluid. In this clip, a
part is cut off from a piece of stock.
Page 20
Figure 2.07
Figure 2.08
TRAINING EXPERIENCE CHAPTER 2
2.2.4. Drilling
A lathe can also be used to drill holes accurately
concentric with the centerline of a cylindrical part. First,
install a drill chuck into the tail stock. Make certain that
the tang on the back of the drill chuck seats properly in the
tail stock. Withdraw the jaws of the chuck and tap the
chuck in place with a soft hammer. Move the saddle
forward to make room for the tailstock. Move the tailstock
into position, and lock it. (Otherwise it will slide backward
as you try to drill). Before starting the machine, turn the spindle by hand. You've just moved
the saddle forward, so it could interfere with the rotation of the lathe chuck. Always use a
center drill to start the hole. You should use cutting fluid with the center drill. It has shallow
flutes (for added stiffness) and doesn't cut as easily as a drill bit. Always drill past the
beginning of the taper to create a funnel to guide the bit in. In this clip, a hole is drilled with a
drill bit. Take at most one or two drill diameters of material before backing off, clearing the
chips, and applying cutting fluid. If the drill bit squeaks, apply solvent more often. The drill
chuck can be removed from the tail stock by drawing back the drill chuck as far as it will
easily go, then about a quarter turn more. A pin will press the chuck out of the collet.
2.2.5. Boring
Boring is an operation in which a hole is enlarged
with a single point cutting tool. A boring bar is used
to support the cutting tool as it extends into the hole.
Because of the extension of the boring bar, the tool
is supported less rigidly and is more likely to
chatter. This can be corrected by using slower
spindle speeds or by grinding a smaller radius on
the nose of the tool.
2.2.6. Single Point Thread Turning
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Figure 2.09
Figure 2.10
TRAINING EXPERIENCE CHAPTER 2
External threads can be cut with a die and internal threads can be cut with a tap. But for some
diameters, no die or tap is available. In these cases, threads can be cut on a lathe. A special
cutting tool should be used, typically with a 60 degree nose angle. To form threads with a
specified number of threads per inch, the spindle is mechanically coupled to the carriage lead
screw. Procedures vary for different machines.
In addition to that I learned little bit of advanced work piece holding techniques,
Some parts require special techniques to hold them properly for lathe work. For instance, if
you wish to cut on the entire outside diameter of a part, then the part cannot be held in a
chuck or collet. If the part has a hole through it, you can press it on to a lathe arbor (a slightly
tapered shaft), and clamp onto the arbor rather than the part itself. The hole must have an
adequate aspect ratio or the part will not be firmly supported. If the part has a very large hole
through it, a lathe arbor may not be a practicable solution. You may instead use the outside of
the jaws to hold the inside diameter of the part. If the part has a very complex geometry, it
may be necessary to install the part onto a face plate. The face plate is then attached to the
spindle.
2.2.7. Work Carried Out Using the Lathe Machine
I was given some parts used in clay mixing machine to finish. I have finished all the parts that
were given to me within few weeks. There I learned to cut a taper angle, learned to cut
threads and carried out a break drum cutting operation too. All the drawings are attached to as
annexes.
In addition to that I involve repairing a lathe machine having a problem with its self action
unit. In the self action unit a inspected all the gear wheels because first I thought it was due to
metal dust stuck within the gear wheels. But it wasn’t the issue. Issue was guide ways of a
gear wheel displaced to wards a side. So they were contact with each other generating friction
between those two. So I had to realign and clean all the iron partials inside of the self action
unit.
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TRAINING EXPERIENCE CHAPTER 2
2.3. BASIC SHAPING MACHINE PROCESSES
The main function of the shaping machine is the production of flat surfaces, which are
obtained by combining a line tool cut with a perpendicular feed. To understand how this
machine generates a plane surfaces, it is easiest to consider the surface parallel to the machine
table. The ram of shaping machine moves the cutting tool backward and forward in straight
line. Each time the tool moves backward the tool lifts clear of the work piece and the work
piece moves across in a path perpendicular to the tool movement. The work remains
stationary during the forward (Cutting) stroke of the tool, and only moves across by one
cross-traverse increment during the return (Non-cutting) stroke. The appearance of the
machined surface is of a succession of closely spaced, straight line cuts. For this reason, it is
often referred to as a ruled surface.
2.3.1. Work Holding
There are several ways of holding the work piece on a shaping machine. The most
usual is to use a swivel vise. In order to produce accurate work, it is essential that the fixed
jaw and the upper surfaces of slides of the vice be accurately aligned with the machine
worktable. After the vise has been positioned for a particular job, it should be checked for
alignment. Large job may be mounted directly on the machine table using clamps or dogs.
Surfaces may be machined perpendicular to each other using the side of the table. The side of
the table is often provided with a ‘V’ for holding cylindrical too.
Page 23
Figure 2.12
TRAINING EXPERIENCE CHAPTER 2
2.3.2. Tools
One of the great advantages of the shaping machine for jobbing- shop work is the fact
that it uses cheap, single point tools similar to lathe tools. Further, these tools can be ground
off-hand when it is necessary to change their shape to suit a particular job, or to re-sharpen
them. Some typical shaping machine tools, in which the similarity to lathe tools is evident.
2.3.3. Types of Shaping Machine
Shapers are mainly classified as standard, draw-cut, horizontal, universal, vertical, geared,
crank, hydraulic, contour and traveling head. The horizontal arrangement is the most
common. Vertical shapers are generally fitted with a rotary table to enable curved surfaces to
be machined. The vertical shaper is essentially the same thing as a slotter (slotting machine),
although technically a distinction can be made if one defines a true vertical shaper as a
machine whose slide can be moved from the vertical. A slotter is fixed in the vertical plane.
Very small machines have been successfully made to operate by hand power. As size
increases, the mass of the machine and it’s the power requirements increase, and it becomes
necessary to use a motor or other supply of mechanical power. This motor drives a
mechanical arrangement (using a pinion gear, bull gear, and crank, or a chain over sprockets)
or a hydraulic motor that supplies the necessary movement via hydraulic cylinders.
2.3.4. Operation of the Shaping Machine
Page 24
Figure 2.13
TRAINING EXPERIENCE CHAPTER 2
A shaper operates by moving a hardened cutting tool backwards and forwards across the
work piece. On the return stroke of the ram the tool is lifted clear of the work piece, reducing
the cutting action to one direction only.
The work piece mounts on a rigid, box-shaped table in front of the machine. The height of the
table can be adjusted to suit this work piece, and the table can traverse sideways underneath
the reciprocating tool, which is mounted on the ram. Table motion may be controlled
manually, but is usually advanced by automatic feed mechanism acting on the feed screw.
The ram slides back and forth above the work. At the front end of the ram is a vertical tool
slide that may be adjusted to either side of the vertical plane along the stroke axis. This tool-
slide holds the clapper box and tool post, from which the tool can be positioned to cut a
straight, flat surface on the top of the work piece. The tool-slide permits feeding the tool
downwards to deepen a cut. This adjustability, coupled with the use of specialized cutters and
tool holders, enable the operator to cut internal and external gear tooth profiles, splines,
dovetails, and keyways.
The ram is adjustable for stroke and, due to the geometry of the linkage, it moves faster on
the return (non-cutting) stroke than on the forward, cutting stroke. This action is via a slotted
link or whit worth link.
2.3.5. Safety on the Shaping Machine
We have already referred to safety in chapter 02. The shaper is not any more
dangerous than other machine, but as some people will get in to trouble in the most innocent
situations if may be worthwhile to issue a few words of advice. Most of the other machine
tools have their chief source of danger in members which rotate, the only rotating hazards on
the shaper is the squared shaft which projects from the side of the machine for setting the
stroke, and this can be dangerous if after setting a stroke we forget to remove the handle from
it before starting up. It is also a good precaution not to lean anywhere near this, as the rotating
squared end could wind up in the loose clothing. The ram is the only other real source of
danger, and accidents can occur both by forgetfulness and by knowingly taking chances.
On modern, moisturized, gear driven machines, the danger from an obstruction to the
ram is greater than it was on the earlier belt-driven types, since a belt would often save a
Page 25
TRAINING EXPERIENCE CHAPTER 2
serious situation by slipping off. A train of gearing from a high-speed motor, however, is not
so obliging. The ram, therefore, should always be considered as a source of danger, and this
should never be forgotten, neither should a known risk be entertained. After setting or
resetting a job, make sure that neither the tool nor any portion of the ram will foul anything
on the table before starting the machine. Better still; pull the machine round by hand to make
sure. There is sometimes a temperate to change the stroke or the setting of the ram while the
machine is running. This is taking a known risk and should be avoided. Special care is
necessary when a fine setting to the forward end of the stroke is necessary for shaping up to
an obstruction, and the machine should be pulled round several times before it is started up.
Many mishaps occur through work being insecurely clamped and supported against
the force of the cut and it should be remembered that the tool at the beginning of each stroke
exerts a considerable shock force. Stops should always be used when jobs are clamped direct
to the table and clamping should be arranged to come on to solid metal. Faulty clamping and
setting up, as well as being dangerous, lead to inaccurate results due to work either moving or
distorting. Even if a job is well clamped, it may be pushed off the table, or the tool broken, by
winding in to a large cut that was not checked or has jumped on due to a loose head slide.
The collection of the cutting chips on a shaping machine is a problem that has never
been solved, and when dealing with hard steel particularly it is advisable not to stand at the
front of the machine. Also, sweep the floor often if you value the leather on your shoe soles.
2.3.6. Work Carried Out Using Shaping Machines
In my training at the IDB I Frequently used this machine to complete works assigned to me.
Among them I shaped some parts that use in clay mixing machine. There were key ways and
taper angle to cut so I performed those operations also using the shaping machine. I have
attached all the drawings of the parts, carried out by my self. Clay mixing machine is one of
the on going project in IDB these days. It was the main project and also there are some other
projects too. Purpose of making those products is to improve the productivity of the local
industries as well as the self employment. I was very lucky to contribute my effort and
knowledge to empower self employees in the country because I believe it’s the true
development of this country.
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TRAINING EXPERIENCE CHAPTER 2
2.4. BASIC MILLING MACHINE COMPONENTS AND PROCESSES
1.Face milling cutter
2.Spindle
3.Spindle head
4.Column
5.Table
6.Saddle
7.Knee
8.Base
9.Spindle switch
10.Spindle speed gear lever
11.Spindle speed control lever
12.Oil tank
Milling machines are very versatile. They are usually used to machine flat surfaces, but can
also produce irregular surfaces. They can also be used to drill, bore, cut gears, and produce
slots. The type of milling machine most commonly found in student shops is a vertical
spindle machine with a swiveling head. Although there are several other types of milling
machines, this document will focus only on the vertical milling machine.
A milling machine removes metal by rotating a multi-toothed cutter that is fed into the
moving work piece. The spindle can be fed up and down with a quill feed lever on the head.
Page 27
Figure 2.14
Figure 2.15
TRAINING EXPERIENCE CHAPTER 2
The bed can also by feeding the x, y, and z axes manually. In this clip the z axis is adjusted
first, then the y, than the x.
Once an axis is located at a desired position and will no longer be fed, it should be locked
into position with the Gibb locks.
Most milling machines are equipped with power feed for one or more axes. Power feed is
smoother than manual feed and, therefore, can produce a better surface finish. Power feed
also reduces operator fatigue on long cuts. On some machines, the power feed is controlled
by a forward reverse lever and a speed control knob.
2.4.1. Rotating the Head
The head of a vertical milling machine can be tilted from side to side and from front to back.
This allows for versatility of the machine, but these adjustments can drift.
2.4.2. Squaring the Vise
Work on a milling machine is most often held in a vise clamped onto the bed. To make
features aligned with the edges of the stock, it's necessary to align the vise with the feed axes
of the mill. To do this, mount the vise on the bed and secure it with T-bolts, but only lightly
and do adjustments of the orientation of the vise to make it align. Then tighten down the T-
bolts be careful not to change the vise orientation. Recheck the alignment of the vise.
2.4.3. Types of Milling Cutters
Page 28
Figure 2.16
Climb Milling Conventional Milling
TRAINING EXPERIENCE CHAPTER 2
In vertical mills, milling cutters with solid shafts are usually used. Milling cutters with keyed
holes are predominantly for use in horizontal mills. End mills are designed for cutting slots,
keyways and pockets. Two fluted end mills can be used to plunge into work like a drill. End
mills with more than two flutes should not be plunged into the work. Ball end mills can
produce a fillet. Formed milling cutters can be used to produce a variety of features including
round edges.
2.4.4. Removing and Installing Milling Cutters
To remove a tool, move the quill to the highest position and lock it in place. Then, engage the
brake while loosening the draw bar with a wrench. Ensure that the draw bar's threads are still
engaged in the collet. Tap on the end of the draw bar to release the collet from the spindle. If
the threads of the draw bar are not engaged, the milling cutter will fall, and could be
damaged. Finally, unscrew the drawbar from the collet.
To install a tool, place the desired milling cutter in a collet that fits the shank of the cutter.
Insert the collet into the spindle. Ensure that the key way on the collet mates properly with
the key in the spindle. While holding the tool with one hand, start the threads of the draw bar
into the collet by hand. Use a wrench to tighten the drawbar down with one hand while
holding the brake.
2.4.5. Climb and Conventional Milling
When milling, one should be aware of the difference between conventional, and climb milling. In conventional milling, the work piece is fed into the rotation of the cutter. This type of cut requires lower forces and is preferred for roughing cuts. In climb milling, the work
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Figure 2.17
TRAINING EXPERIENCE CHAPTER 2
moves with the rotation of the cutter. This produces a better finish. It is not recommended if the work piece cannot be held securely or cannot support high forces.
2.4.6. Calculating Speed and Feed
Cutting speed refers to the speed at which the tool point of the cutter moves with respect to
the work measured in feet per minute. Feed is the rate at which the work moves into the
cutter measured in feed per tooth revolution. Feeds and speeds affect the time to finish a cut,
tool life, finish of the machined surface and power required of the machine.
The cutting speed is mostly determined by the material to be cut and the material of the tool.
To find the right speed for any task, refer to the Machinery's Handbook or other reference. To
calculate the proper spindle speed, divide the desired cutting speed by the circumference of
the tool expressed in feet. The feed rate depends on the width and depth of cut, finish desired
and many other variables. To calculate the desired feed setting from the feed rate, multiply
feed per tooth per revolution by number of teeth and rpm of the spindle.
2.4.7. Setting Spindle Speed
Spindle speed is varied by changing the geometry of the drive train. On many modern
machines, it can be adjusted continuously with a hand crank. The spindle must be turning to
make the adjustment. A dial indicator reads the speed in rpm. The spindle speed dial indicator
shown above has two scales, one for low range, and one for high range. The machine is
switched between ranges with a lever. Sometimes, the spindle must be rotated slightly to
allow the gears to mate properly.
2.4.8. Using the Edge Finder
Before doing precise work on a milling machine, one must locate the edges of a part
accurately. An edge finder is designed to help you do this. An edge finder is composed of two
concentric cylinders, spring loaded together. To use it, offset the two halves slightly so that
there is a wobble as it spins. Then, move the part into the tool slowly. The edge finder will
center up, and then break out of concentricity suddenly. At that point, reset the dial indicator
or digital readout for that axis of the machine to a value equal the radius of the edge finder.
Repeat the process at least once.
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TRAINING EXPERIENCE CHAPTER 2
2.4.9. Using the Micrometer Dials
Most milling machine manual feeds are equipped with dial indicators. If you know how far
you want to feed the bed, you can set the dial indicator to that number (in thousandths of an
inch). Just turn the locking ring counterclockwise to free the dial indicator, set the dial, and
lock in the setting. Be certain that the backlash in the mechanism driving the table is taken up
prior to setting the dial indicator.
Many modern machines have digital readouts. These are preferred since they measure the bed
position directly so you need not be concerned with backlash. They also read out bed position
in metric units if desired.
2.4.10. Face Milling
It is often necessary
to create a flat face
on a large part. This can be done best with a facing cutter.
Select a cutter about one inch wider than the work piece
so that the facing can be accomplished in one pass.
2.4.11. Milling Slots
End mills are designed to cut square slots. They will
produce a slot to within two one thousandths of an
inch in one pass. If greater accuracy is required, use an
end mill a little smaller than the desired slot. Measure
the slot produced and opens it to the desired
dimension with a second pass. The following clip
shows and end mill cutting a slot. Note that the depth
of cut is approximately equal to the diameter of the
cutter.
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Figure 2.18
Figure 2.20
TRAINING EXPERIENCE CHAPTER 2
2.4.12. Advanced Work Holding
To hold round stock more securely in a vise, use a v-block. The work can be held vertically
or horizontally. Round stock often cannot be held securely in the vise without damaging the
work. A collet block is designed to hold round stock. Square collet blocks allow the part to be
indexed to put in features at 90 degree increments. To mill features at 60 degree increments,
use a hexagonal block.
A work piece can be set up easily when the desired features are parallel with or perpendicular
to the work piece edges. When the features are at an angle to the edges, more ingenuity is
required. Here, an angle plate is used to set the position of a vise within a vise. Thus a slot
can be milled into a work piece at any desired angle.
Some parts don't fit well into a vise. These parts can be secured directly to the bed of the
machine with hold down clamps. It is good practice to create a gap between the bed and the
work with parallels. The clamps should be tilted down slightly into the work.
To create circular features on a mill, a rotary table can be installed onto the bed. The table
allows the work piece to be rotated. A dial indicator allows precise control of the angle of
rotation.
2.5. GRINDING MACHINES
At the IDB training I was also able to use grinding machines. There were two types of
grinding machines. They are Bench grinder and Surface grinder.
2.5.1. Bench Grinder
A bench grinder is a type of bench top grinding machine used
to drive abrasive wheels. A pedestal grinder is a larger version
of a bench grinder that is mounted on a pedestal, which is
bolted to the floor. These types of grinders are commonly used
to hand grind cutting tools and perform other rough grinding.
Depending on the grade of the grinding wheel it may be used
for sharpening cutting tools such as lathe tools or drill bits.
Alternatively it may be used to roughly shape metal prior
to welding or fitting. A wire brush wheel or buffing wheels can be interchanged with the grinding
wheels in order to clean or polish work-pieces. Grinding wheels designed for steel should not be used
for grinding softer metals, like aluminum. The soft metals get lodged in the pores of the wheel and
expand with the heat of grinding. This can dislodge pieces of the grinding wheel.
2.5.2. Surface Grinder
Surface grinding is used to
produce a smooth finish on
flat surfaces. It is a widely
used abrasive
machining process in which
a spinning wheel covered in
rough particles (grinding
wheel) cuts chips of metallic
or non metallic substance
from a work piece, making a
face of it flat or smooth
2.5.3. Work Carried Out Using Grinding Machine
Mostly I used bench grinding machine to sharpen tools and etc. when I use grinding tool I used eye protecting glasses too. Because some heated small metals particles can cause damages to our eyes.
Also I used surface grinding machine to get a shining surfaces to metal parts. When we want precise measurements to our work piece these machines very helpful achieve those precise dimensions.
2.6. OXY-ACETYLENE CUTTING AND ELECTRIC ARC WELDING
Within the last few weeks of my training I was granted an opportunity to work in welding
section. In the welding section mainly there are two types of categories used to perform
cutting and welding. They are,
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Figure 2.22
TRAINING EXPERIENCE CHAPTER 2
2.6.1. Oxy-Acetylene Cutting
Within the first week of welding section I learned about oxy-acetylene cutting process. First I
started learning oxy-acetylene cutting fundamentals. At the begging I was familiar with all
the components used in oxy-acetylene cutting like torch, regulators, hoses, striker, etc. and
some basic steps like, how to fire up the torch, how to keep hoses when cutting the metal,
importance of holding breath till the cutting finished and how to control oxygen and
acetylene percentages to get the required flame. Also studied about the safety equipments that
will mention in another section and few safety procedures to follow when cutting metals as I
mentioned bellow,
a. Make sure the regulators are tight
b. Never use oily rags around cylinders and regulators
c. Check hoses and make sure mixing knob is off before lighting the torch.
d. Make sure regulators are in the proper settings. (15 psi max. acetylene 40 psi max.
oxygen)
e. Light acetylene first then mix oxygen
2.6.2. Electric Arc Welding
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Equipments used in gas weldingFigure 2.23
TRAINING EXPERIENCE CHAPTER 2
Once I got experience of oxy-acetylene cutting I started learning electric arc welding. Same
as above mentioned I learned basics, familiar with equipments and started practicing it.
Regarding the electric arc welding section I found that there are so many safety issues while I
was practicing. Cables and other equipments are damaged. Safety equipments are broken. No
replacement for those broken equipments. Also there were no any notices regarding the safety
steps so I prepared a one and put it in the notice board to enlighten others about safety.
I listed some of them bellow,
Always wear proper clothes when welding.
Place ground lead on material before turning machine on.