LAPORAN PRAKTIKUM PROSES MANUFAKTUR MODUL 1 TURNING

OLEH : KELOMPOK : 28 ANGGOTA : 1. Astrid Parama Ningrum (13406026) 2. Bona Mangkirap (13406043) 3. Irma Sofiani (13406049) 4. Nadia Fadhilah Riza (13406069) 5. Prila Sista Lilly Jane (13406080) 6. Ira Wulandari (13406094)

LABORATORIUM TEKNIK PRODUKSI PROGRAM STUDI MESIN

INSTITUT TEKNOLOGI BANDUNG 2007

Purpose

1. Participants understand the construction of a lathe and how to operate it

2. Participants understand the processes of turning

3. Participants understand the parameters of turning process and how to

determine them.

Basic Theory

Turning is a machining process in which a single point tool removes material from

the surface of a rotating cylindrical workpiece. The tool is fed linearly in a

direction parallel to the axis of rotation, as illustrated below.

Turning is traditionally carried out on a machine tool called lathe, which provides

power to turn the part at a given rotational speed and to feed the tool at a

specified rate and depth of cut.

Principal components of an engine lathe:

Headstock contains the drive unit to rotate the spindle, which rotates the

work

Tailstock, opposite the headstock in which a center is mounted to support

the other end of the workpiece

Tool post is where the cutting tool is held

Cross-slide is where the tool post is fastened, designed to feed in a

direction perpendicular to the carriage movement

Carriage is designed to slide along the ways of the lathe in order to feed

the tool parallel to the axis of rotation

Ways are like tracks along which the carriage rides, and they are made

with great precision to achieve a high degree of parallelism relative to the

spindle axis

The Bed of the lathe provides a rigid frame for the machine tool

Leadscrew drives the carriage rotating at the proper speed to obtain the

desired feed rate

Equation for turning parameters:

Cut rate 1000

.. Ndvc

Feed rate Nfv f .

Depth of cut 00

2

)(d

ddd m

Cutting time f

tc

v

lt

Material Removal Rate cvAfMRR ..

where: d0 = original diameter of the part (mm)

dm = final diameter of the part (mm)

f = feed rate (mm/r)

lt = length of the cylindrical workpart (mm)

A = Area of the workpart

N = rotational speed (rev/min)

MRR = material removal rate(mm3/min)

tc = cutting time (s)

vf = cutting speed (mm/rot)

Operations related to turning:

Facing

The tool is fed radially into the rotating work on one end to create a flat

surface on the end

Taper turning

Instead of feeding the tool parallel to the axis of rotation of the work, the

tool is fed at an angle, thus creating a tapered cylinder of conical shape.

Contour turning

The tool follows a contour that is other than straight, thus creating a

contoured form in the turned part

Form turning

In this operation, sometimes called forming, the tool has a shape that is

imparted to the work by plunging the tool radically into the work

Chamfering

The cutting edge of the tool is used to cut an angle on the corner of the

cylinder, forming what is called a chamfer

Cutoff (parting)

The tool is fed radially into the rotating work of some location along its

length to cut off the end of the part

Threading

A pointed tool is fed linearly across the outside surface of the rotating

workpart in a direction parallel to the axis of rotation at a large effective

feed rate thus creating threads in the cylinder

Boring

A single-point tool is fed linearly, parallel to the axis of rotation, on the

inside diameter of an existing hole in the part

Drilling

Drilling can be performed on a lathe by feeding the drill into the rotating

work along its axis

Knurling

Metal forming operation used to produce a regular cross-hatched pattern

in the work surface

Analysis

Astrid Parama Ningrum (13406026)

In our practicum, we did turning process and there are processes that

we try, such as facing, centre boring, diameter reducing, grooving and

threading.

We set the lathe in zero coordinate to avoid backlash that will affect the

turning processes.

In facing processes, the surface of specimen have a coarse. It might

because of the cutting tool have defect.

Cutter which used for facing, centre boring and diameter reducing

processes is different with cutter in grooving and threading processes.

Cutter that practican used be changed to avoid damage on cutter. But

it is better to change the cutting tool in every process.

In centre boring processes we make the space for the holder to reduce

vibration in the work piece

Turning processes with lathe did not used backlash compensator, but

we did alternative ways such as turning the hand wheel unto the

opposite direction two times to reduce the gap between gears.

The speed of spindle must be higher so lathe can make better surface

finish and to treat the cutter tool better. Because in low rate, the spindle

will damage the cutter.

The turning processes wil have bad result if the feed rate higher. It

means the workiece move faster and would make the surface not flat

In turning processes needed the concentration of operator to make

sure the result is as it wants. The dimension of specimen is depending

with the operator, so it is not good to producing.

In reducing diameter the specimen will be cut off if the operator let the

lathe keep running.

Bona Mangkirap (13406043)

- While doing facing process, the zero position of the cutting tool and cutting

placement will affect facing result. a bad facing result twill have scrap on it

surface and it will affect on centre boring and centre drilling process.

- In the observation ,the centre boring process mean to give place for the

nipper so the work piece will have no vibration caused by threading

process that can make the result bad. The other reason of the flanking is

to reduce the resulted moment.

- The work piece must not be nip to long from the spindle because it will

increase the moment which means the work piece will be more unstable.

- Cutter must be changed in every process because each process need

different cutter. If a wrong cutter used in wrong process it will damaged the

cutter.

- Higher spindle rate will produced a better surface finish and longer cutter’s

life. Because low spindle rate will make greater impact for the cutter which

will damage the cutter greater.

- Higher feed rate will make the turning result worse. Because which means

the work piece will move fast and maybe skip the cut, so the surface result

will not flat.

- A bad result in threading process happened in the observation, it because

when locate the zero position for threading process there’s an error so

depth of cut become to deep and the threading result become unarranged

and full of chip left. While a good one will provide a better surface (without

chip) with good thread result.

- In reducing diameter process, we cannot cut the work piece too deep

because it will damage the cutter, so if you want to make a deep cut, you

must do the process several times in small depth.

- Backlash in turning process will affect the zero position. To overcome this

problem, we must locate the cutter again after turning the work piece.

About 1 to 2 times rotation.

Irma Sofiani (13406049)

We did 5 processes in this experiment, there are: Facing, center boring,

reduction diameter, grooving and threading. Each process needs different

types of cutting tools. A wrong placement of cutting tool may defect the

product and damaged the cutter also. In each process, we also need to

determine the zero position of cutting tool in addition to produced a good

quality product.

In facing process, a fault in determining zero position will result a scrap on

the surface of work piece therefore will affected the center boring process.

The centre boring process means to give the nipper place, so that the work

piece would not bent and rebound. We set the work piece and flanked it.

So that the work piece would have no vibration and moment force caused

by threading process which can make the bad result. A long process of

threading process will turn to a cutting process.

The work piece should place not to far from the nipper, in order to

decrease the moment force so that it will stable

Higher spindle rate will produced a better (smooth) surface result and

longer cutter’s life. Because the low spindle rate will make a bigger impact

to the cutter and it will damage the cutter

Higher feed rate would make the surface of work piece worse; it will be

rough and have scrap on it. Because if work piece move faster it probably

will skip the cut, so that the surface will not smooth

In this experiment, the threading process appeared to be failed. There are

two reasons two explained it. First, the age of cutting tool is too old, so that

it already dull. This condition result a bad effect on the work piece, such us

rough and scraped. The second one is the human error. A zero positioning

was un-located in the same order, so there are two different thread piled

up.

In reducing diameter process, deeper depth cut will damaged the cutting

tool. If we want to create a deep cut, we have to repeat the process

several times

Nadia Fadhilah Riza (1306069)

In this turning experiment, we did 5 processes, which are facing, centre boring,

diameter reduction, grooving, and threading.

Each turning process needed different types of cutting tools. For facing, centre

boring, and diameter reduction process used the same cutting tool. For grooving

and threading process were both using different types of cutting tool. If a wrong

cutting tool used in the wrong process, it would damaged the cutting tool.

First, we have to decided the zero position of the cutting tool, which would effect

the surface of the workpiece. A false zero position would effect the result of

facing process, even more, the centre boring process.

The centre boring process mean to give the holder place, so that the work piece

would not bent and rebound. If the workpiece not been holded, workpiece would

have endurance limit cause of the dynamic force from the cutting tool. The

workpiece might not holded to far in the holder, which means the work piece

located far from the spindle that would increase moment force to the workpiece.

In threading process, if we did the process at a long time, the process would turn

out to be a cut-off process.

The chips were formed in several ways. In centre boring, facing and diameter

reduction process the chips were continuous and short. This was caused by

relatively small feeds and depths. In threading process, the chips were

segmented (caused by the cuting tool’s damaged edge) and long (caused by

small feed and small depth).

Higher spindle rate would produce a smoother surface workpiece and longer

cutting tool’s life. A low spindle rate would make a greater impact for the cutting

tool which would make a greater damage to the cutting tool. Higher feed rate

would make the surface of workpiece rougher.

There is a small box attached to the lead screw that contains a few gears that can

be used to control the lead screw for threading process. Each gear is compatible

for a few number of feeds. The adjustments on the used gear should match with

what we adjusted previously on the feed. If it is different, it could cause defects

on the thread.

A bad result in threading process happened in this experiment. It happened

because when the operator located the zero position for threading process

there’s an error occurred, so depth of cut become too deep, the threading

process result become unarranged, and the surface of workpiece was covered of

chips.

A broken cutting tools would make the chips covered the surface of the

workpiece.

The used turning macine did not use a backlash compensator. Backlash in

turning process will effect in deciding the zero position. To overcome this

problem, we must always located the cutting tool after the turning process work

on the workpiece. But there is a way to compromise the backlash without any

additional component attched to the turning. That is by turning the handwheel to

the opposite direction two times in order to reduce the gap between gears.

Prilla Sista LJ (13406080)

1. With a high cutting speed, we could get smooth turning result. If the cutting

speed is lower than the feed, thread could be formed on the workpiece

surface.

2. In the turning process, there is a plane particularly designed for the flow of

the chips so they will flow out themselves. Because if the chips stay, the

friction that occurs could resist the feed and wear out the cutting tool.

3. In threading process, the depth of cut could not be too deep in a turning

process because it could wear out and even break the cutting tool.

Therefore, to make a deep cut thread, the process should be done in many

times.

4. Each turning process has different types of cutting tools needed.

Therefore, the cutting tool should be replaced with the proper one for

every turning process.

5. From the observation we could see the backlash that occurs on the

worktable whereas we rotate the spindle that moves the worktable once

and twice, the table has not moved yet. To overcome this problem, we

should rotate the spindle two more than the rotation needed.

6. The result of the turning process might not be appropriate to our required

dimension. It could be caused by the setting of 0 position before the

process was not very precise.

Ira Wulandari (13406094)

We do the observations of turning process in three base process which are

facing, diameter reduction and threading.

First, we do the facing process to create a flat surface on the end. Then we do the

reduction of the diameter. In this case the diameter that we reduced is the inside

diameter. Finally, we observe the making of threading.

The threading processes have several steps. We cannot do the threading directly

into the depth we want because it can damage the cutting tools. We also have to

be careful with exchange every cutting tools when we do the different process, it

is also can be the cause of damaging cutting tools. (It happened on the previous

observations.)

The chips were formed in many ways. In centre boring, facing and diameter

reduction process the chips were continuous and short. This was caused by

relatively small feeds and depths. In threading process, the chips were

segmented (caused by the cuting tool’s damaged edge) and long (caused by

small feed and small depth)

Higher spindle rate will produced a better surface finish and longer cutter’s life,

because low spindle rate will make greater impact for the cutting tools which will

damage the form of the work piece. Higher feed rate will make the turning result

worse. It can happen because the work piece will move fast and maybe skip the

cut, so the surface result will not flat.

Backlash in turning process will affect the zero position. To overcome this

problem, we must locate the cutter again after turning the work piece. About 1 to

2 times rotation. A bad result in threading process happened in this experiment. It

happened because when the operator located the zero position for threading

process there’s an error occurred, so depth of cut become too deep, the

threading process result become unarranged, and the surface of work piece was

covered of chips.

The used lathe didn’t use a backlash compensator. But there is a way to

compromise the backlash without any additional component attched to the lathe.

That is by turning the handwheel to the opposite direction two times in order to

reduce the gap between gears.

There is a small box attached to the lead screw that contains a few gears that can

be used to control the lead screw for threading process. Each gear is compatible

for a few number of feeds. The adjustments on the used gear should match with

what we adjusted previously on the feed. If it is different, it could cause defects

on the thread

Prilla Sista Lily Jane

Conclusion

1. Principal components of an engine lathe is:

Headstock contains the drive unit to rotate the spindle, which rotates

the work

Tailstock, opposite the headstock in which a center is mounted to

support the other end of the workpiece

Tool post is where the cutting tool is held

Cross-slide is where the tool post is fastened, designed to feed in a

direction perpendicular to the carriage movement

Carriage is designed to slide along the ways of the lathe in order to

feed the tool parallel to the axis of rotation

Ways are like tracks along which the carriage rides, and they are made

with great precision to achieve a high degree of parallelism relative to

the spindle axis

The Bed of the lathe provides a rigid frame for the machine tool

Leadscrew drives the carriage rotating at the proper speed to obtain

the desired feed rate

2. Turning is a machining process in which a single point tool removes

material from the surface of a rotating cylindrical work piece

3. Processes of turning:

a. Facing process

b. Diameter reduction process

c. Threading process

d. Taper turning

e. Contour turning

f. Form turning

g. Cut-off

h. Drilling

i. Boring

j. Knurling

k. Chamfering

4. The shape of the cutting tool used and the direction of the feed vary

between processes

5. Parameters of turning process:

a. Cutting Speed, it’s connected with rotational speed and the average

diameter of work piece.

b. Depth of cut can be defined by adjusting the position of cutting tool

using the spindle. Depth of cut affects the final dimension of the

work piece. In reducing diameter process, depth of cut affects the

final dimension of work piece. However, in facing process depth of

cut affects the thickness of material removal.

c. Feed, can be define by the selector lever. The direction of Feed

affects the final dimension of work piece. If the purpose of turning is

fed the circumference of work piece’s surface, then the direction

would be axial. In the other hand, if the purpose of turning process

is fed the edge of the work piece, then the direction would be radial.

d. Length of cut is the size of the work piece that has been done by

turning process. It is affected by feed rate and time of cutting.

Those parameters, determine the result of turning process.

Post Observation Task

1. Describe and sketch the procedure of turning processes that has been done

during the observation:

a. Facing process

Set the cutting tool in a right position. Set it in the toolspot. In

order to put the cutting tool on the centre of workpiece.

Adjust the position of the cutting tools in one line with longitude of

the engine lathe. Then, rotate the cutting tools to 45 degrees.

Set the depth of cut by setting the distance of cutting tool and

workpiece. This can be done by setting the toolpost.

Set the direction of feed and the feed rate.

Turning process.

facing process

b. Diameter reduction process

At first, one edge of the work piece is drilled with a center drill

attached on the tailstock

The cutting tool is positioned at 90 cutting angle

Adjust the direction and the feed rate (vf) by adjusting the feed

rate selector lever as required.

Adjusting the depth of cut (a): by adjusting the position of cutting

tool with the spindle.

Turning process

Diameter reduction process

Diameter reduction result

c. Threading process

At first, does the grooving process, which is making a clear final,

mark for the threading process. The grooving process uses the

grooving tool. The depth of grooving is equal to the depth of

thread that is going to be done.

Setting the required pitch: the size of pitch is set by the gear box

according to the specifications needed.

Setting of threading dial: by checking the lead screw nipper, the

gear inside should match the specification stated on the

threading process table.

Turning process

grooving threading process

2. Write the name and function of the engine lathe components that were used

during the observation!

Headstock contains the drive unit to rotate the spindle, which rotates the

work

Tailstock, opposite the headstock in which a center is mounted to support

the other end of the workpiece

Tool post is where the cutting tool is held

Cross-slide is where the tool post is fastened, designed to feed in a

direction perpendicular to the carriage movement

Carriage is designed to slide along the ways of the lathe in order to feed

the tool parallel to the axis of rotation

Ways are like tracks along which the carriage rides, and they are made

with great precision to achieve a high degree of parallelism relative to the

spindle axis

The Bed of the lathe provides a rigid frame for the machine tool

Leadscrew drives the carriage rotating at the proper speed to obtain the

desired feed rate

3. Draw the shape of cutting tools and show the varieties of their angles and

planes!

AL and AR type for boring, chamfering and turning processes that allow 90

angle.

BL and BR type for turning, boring dan chamfering, suitable for roughing.

Have the lead angle of 15.

Type C has a square end, commonly used for turning, boring and

chamfering.

Type D has 800 angle and an angle tool for undercutting O.D/I.D

chamfering

Type E is a standard cutting tool with 60 that is usually used for V-

grooving, chamfering, boring, turning, and facing

EL and ER type have 600 angle to offset a part that is difficult to reach. Also

suitable for V-grooving.

FL and FR type, commonly used for lathe turret for straddle facing, but

could also be used for conventional lathe

GL and GR type for facing that is close to chuck jaws

CTL and CTR used for cut-off for small diameter, also for grooving

TSA type for boring with boring bar angle of 900

TSC type for boring with boring bar angle of 300

TSE type for boring with boring angle of 450

4. Determine the cutting speed, spindle rotational speed, depth of cut, and

feed rate that are needed to do the diameter reduction and the HSS type of

cutting tool and how to set the arrangement of feed lever?

Lever arrangement setting:

Drill a hole for clamping with drill chuck-center drill

Set the clamp so the workpiece stays rigidly in its place during turning

process.

Set the 0 position, according to the distance of cutting edge and the

surface of workpiece.

Determine and set the depth of cut, spindle rotational speed, and feed in

the machine to our requirement:

In order to arrange the spindle rotational speed, the lever is turned to

letter B, and the other lever is turned to 3 to get the 370 mm/radian

spindle rotational speed.

To set the feed direction, pull or push the lever. Pull the lever to reduce

the workpiece surface. We need to determine the feed rate required

before setting the feed rate of the cutting tool. Then, set the lever. To

create a certain speed for feed rate, in this case 0,05 mm/rad where it is

shown AS8X in the table on the headstock. Set the first lever to letter A,

the second lever to 8, and the third lever to X.

5. Write 3 effects caused by adjusting cutting tool higher than the axis of work

piece !

a. Friction will occur between the chin part of the cutting tool and the

work piece, which could make the finished work piece very thin.

b. The surface of the work piece would be textured (not flat). The

dimension of the finished product might not appropriate to our

requirement. It is commonly found in the facing process.

c. The fracture chips of the cutting tool or the work piece could jump

out of the chuck. If the cutting tool is not placed in the right position,

it could easily wear out. It has to supply more energy because the

cutting edge is not rightly consumed when contacted to the work

piece.

6. Describe the factors initiating the cost of turning process!

a. Cutting Speed , it’s connected with rotational speed and the

average diameter of work piece.

b. Depth of cut , can be define by adjusting the position of cutting tool

using the spindle. Depth of cut affects the final dimension of the wor

piece. In reducing diameter process, depth of cut affects the final

dimension of work piece. However, in facing process depth of cut

affects the thickness of material removal.

c. Feed, can be define by the selector lever. The direction of Feed

affects the final dimension of work piece. If the purpose of turning is

fed the circumference of work piece’s surface, then the direction

would be axial. In the other hand, if the purpose of turning process

is fed the edge of the work piece, then the direction would be radial.

d. Length of cut is the size of the work piece that has been done by

turning process. It is affected by feed rate and time of cutting

e. The machine and its maintainance

A machine with a certain type of quality will have a certain type of

perfomance. This will effect the efficency of electricity. A good

machine will not waste too much electrcity.

f. Set-up

Set-up process will effect the quality of the products. If there is a

mistake in the setting-up process, then there will be a possibilty that

the product produced will have defects

7. Explain and mention the function of knurling process, grooving, and form

turning!

a. Knurling is a turning process that will produce a cubic pattern or

stripe pattern on the surface by using knurling tool. Knurling is also

known as metal working process that is used for regular

crosshatched pattern on the workpiece surface.

b. Grooving is a process that is similar to diameter reduction process

on the edge of threading workpiece. This process is done before

threading in order to make the end of thread. Grooving can be done

in three shapes, which are square, round, and V-shaped.

c. Form Turning is turning process that uses a cutting tool to reduce

the diameter of the workpiece and also to form the workpiece as the

contour of the cutting tool. Form turning needs special templates to

form the workpiece.

Sources

“Diktat kuliah proses manufaktur”, Operasi Pemesinan dan Mesin Perkakas.

Degarmo, E.Paul. ”Material And Processes in Manufacturing”,chapter 18.Shaping and

Planning.

Groover, Mikell P. “Fundamentals of Modern Manufacturing”. John Wiley&Sons,

2002.

Rochim,Taufiq. ”Teori dan Teknologi Proses Pemesinan”, Bab 2 Klasifikasi dan Elemen

Dasar Proses Pemesinan.

http://www.jjjtrain.com/vms/cutting_tools_lathe.html

Enclosure