MCE 332 Manufacturing Processes &Material Science Laboratory

Spring 2014Title: Torsion of Rod

Experiment # : 10Date : 14/05/2014Section # : 2Group # : 4

This report is entirely our own work and we have kept a soft/ hard copy for our own records. It is based on experimental work which we performed in the MCE332L Material & Manufacturing Laboratory. This report and the laboratory work on which it is based, has not been submitted for assessment in any other unit of study. We are aware of the University’s policies on cheating and plagiarism. We understand the safety concerns related to this experiment.

Submitted by:

SR. NO NAME ID SIGNATURE1 Arsalan Ajaz 422472 Mohammad Tishat Chowdhury 399143 Muhammad Umar 447344 Sadikujjaman Bachu 45254

5 Syed Hamdan Mustafa 50262

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Table of Contents

Content Page Number

Abstract 4

Introduction 5

Experimental Setup 7

Data and Results 12

Discussion of Results 13

Sources of Errors 15

Conclusion 16

References 17

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List of Figures and Tables

Figure/Table No. Figure Name Page Number

Fig 1 Slab Milling 5

Fig 2 Side Milling 5

Fig 3 Pocket Milling 5

Fig 4 Profiling 6

Fig 5 Up Milling 6

Fig 6 Down Milling 6

Fig 7 Milling Machine 7

Fig 8 Drill Press 7

Fig 9 Grinding Machine 8

Fig 10 Height Gauge 8

Fig 11 Try Square 9

Fig 12 Vernier Caliper 9

Fig 13 Grinding 10

Fig 14 Slot Milling 11

Fig 15 Facing 11

Fig 16 Final work-piece 11

Fig 17 Dimensions of the work-piece 12

Fig 18 AutoCAD inventor drawing of the product 14

Table 1 Results 12

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Abstract

A milling machine is primarily used in the fields of mechanical, civil, and industrial

engineering, that machines (cuts or shapes) solid materials (mostly metals and its alloys).

Moving or feeding a rotating cutter past the tightly gripped, stationary work-piece, or moving

the specimen radially against the rotating milling cutter can either achieve the chipping away

of the material. Milling machines can be manually operated, mechanically automated, or

digitally automated via ‘computer numerical control’ (CNC). Two milling operations were

conducted in the lab followed by a grinding and drilling operation. The two milling

operations conducted were face milling and Slot Milling (Peripheral Milling). After both the

milling operations were performed, the work piece was grinded that generates a very smooth

surface finish. After grinding, the work-piece was marked again using a height gauge in four

places that were later drilled using a drilling machine, a machine that is used to produce holes

on work pieces to the required diameter using a drill bit. The purpose of the experiment was

to familiarize each student with the different types of milling machines. Each student took

turns in performing different parts of the process in order to gain experience in operating and

understanding the machines. There were no injuries that occurred during the experiment as all

the safety precautions were taken perfectly.

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Introduction

Torsion is defined as the twisting of an object due to an applied torque. The applied torque on

the object produces shear stresses in the torsion rod. The shear stresses are proportional to the

load torque. Here is a figure showing the shear stresses on the rod.

Figure 1: Shear Stresses on the rod

The torque is a property measured in Nm. The formula for Torque is:

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Experimental Setup

Here are a list of tools used in the following experiment:

1) Milling Machine: The milling operations are performed on this machine. Both Face

Milling and Slot Milling were performed on this machine using different tools and

different positioning.

Figure 7: Milling Machine

2) Drill Press: This is used for the drilling operation.

Figure 8: Drill Press

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3) Grinding Machine: This machine is used for the grinding process. This is used to

polish and smoothen the surface finish of the work-piece and make the surface

reflective.

Figure 9: Grinding Machine

4) Height Gauge: This is used to mark the dimensions where the operations were

performed.

Figure 10: Height Gauge

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5) Try Square: This tool was used to make sure the surface was at right angle.

Figure 11: Try Square

6) Vernier Caliper: This tool was used to measure the final dimensions of the work-

piece.

Figure 12: Vernier Caliper

The initial work-piece was a 58 mm by 58mm with a width of 16 mm steel bar. Three

operations were performed on it. Starting with the face milling, followed by the slot

milling. Grinding was also performed and it was ended by creating four holes in the

work-piece. This is discussed in detail in the next section. The final work-piece

measurements are also mentioned in the next section.

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The following procedure is followed to obtain the final product:

The initial measurements are taken of the product using a vernier caliper.

Face Milling is then performed on the edges of the product to obtain the requried

length on a Milling Machine.

The product is constantly checked with the Try Square and right angled corners

are obtained.

The area of the material to be cut during Slot Milling are marked with a height

gauge.

Slot Milling is performed on the Milling Machine.

The work-piece is then taken to the Grinding Machine to get the surface polished.

The work-piece is marked again with the height gauge at the areas where the holes

are supposed to be made.

The work-piece is then taken to the Drill Press and the holes of various diameters

are drilled.

The final measurements of the work-piece is taken using a vernier caliper.

Here are some visual representation of the several procedures done:

Figure 13: Grinding

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Figure 14: Slot Milling Figure 15: Face Milling

Figure 16: Final Work-Piece

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Data and Results

Figure 17: Dimensions of the work-piece

Length(mm) Height(mm)

L1(mm) W1(mm) Hole Diameter(mm)

Required Dimensions

52 15 15 9 20

Final Dimensions

52.55 15.1 15.4 9.4 19.62

% Difference 1.06% 0.667% 2.667% 4.444% 1.9%

Table 1: Results

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L1

W11

Discussion of Results

According to theory low cutting speed along with large feed and depth are used to

remove large amount of material but this produces a rougher surface finish. The speed is then

increased while the feed and depth of cut are decreased to give a smooth finishing of the

product. In this experiment, the cutting speed, feed and depth of cut were kept the same and

not varied. It was quite obvious that milling is a slow process and takes a lot of time as seen

in the experiment. As mentioned above a higher feed rate produced uneven surface finish and

could result in tool damage. Therefore a slower feed rate was used, which gave a smoother

surface finish. The grinding machine was used to further enhance the surface finish as well as

make it shiny and reflective. There are some visible defects seen on the surface of the product

such as scratches and small dents. The hole drilled has a rough surface because reaming

wasn’t done. The milling machine proved to be accurate, as the operations yielded close to

specified measurements. Therefore, the milling machine can produce work parts that have

minimal tolerances with high levels of accuracy. In the part produced it was noted that the

difference in the measurements were about 1.06%, 0.667%, 2.667%, 4.444% and 1.9%

respectively. As a conclusion, the milling and grinding process yielded excellent results.

Given below is the drawing of the product, produced using AutoCAD inventor.

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Figure 18: AutoCAD inventor drawing of the product

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Source of Errors

In this lab session, two of the milling procedures were carried out; one was Slot

Milling (Peripheral Milling) and the other was face milling. The objective of this session was

to machine a part to certain geometry using various procedures and steps. The chances of

errors in this experiment are low as all of the machines used were automated which required

very less human interference and very high dimensional accuracy is achieved at a cost of

material being wasted.

The axis set to zero at the face milling station was approximated by eye vision, so it

might be incorrect and could cause dimensional errors.

The wear and condition of the multiple numbers of teeth on the face milling tool

affects the product. This could cause uneven surface and inaccuracy in dimensions.

The edges of the work piece had to be 90 degrees and this was set using a Try Square

which approximated the angle but did not make it certain. This could add up to errors

causing inaccurate dimensions.

The height gauge used to mark the specimen could have an offset error, yet again

adding up to the errors.

The vibrations caused in the peripheral milling added instability to the procedure and

could have caused dimensional inaccuracy.

In peripheral milling, the interference of the chip produced might hinder the operation

and cause dimensional inaccuracy.

The condition of the drill bit also affects the specimen and adds dimensional

inaccuracy if it has worn out or broken.

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Conclusion

This lab was a good learning experience for everybody as they got to experience

various operations such as face milling, spot milling, grinding, and drilling process. Milling is

an important machining operation performed around the world and hence the understanding

of various milling procedures is essential for any engineer. With the help of a lab instructor,

each member of the team carried out the each process. In addition, the students got the

experience of constructing a desired product with various dimensions from a block of steel.

All the operations were carried out safely by adhering to safety rules and regulations like

using gloves, lab coats, closed footwear, and protective shields to avoid any accidents. Our

aim was to make a part with accurate dimensions and good surface finish. This is one of the

main characteristics of machining operations as it was proved by the low percentage errors in

the earlier section. Overall, this lab was a good learning experience for everybody since the

processes are very important for a mechanical engineer. The experiment turned out to be a

successful one and the understanding of the topic was enhanced for the entire group.

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References

Grinding Machine [Web Graphic]. Retrieved, April 29, 2014, from

http://www.ustudy.in/node/4523

Laboratory Manual (MCE 332L), (10 March, 2014). The American University of Sharjah.

Retrieved from

https://ilearn.aus.edu/webapps/portal/frameset.jsp?tab_tab_group_id=_2_1&url=

%2Fwebapps%2Fblackboard%2Fexecute%2Flauncher%3Ftype%3DCourse%26id

%3D_31475_1%26url%3D

Slab Milling [Web Graphic]. Retrieved, April 29, 2014, from

http://engineering.myindialist.com/wp-content/uploads/2009/10/clip_image00216.gif

Side Milling [Web Graphic]. Retrieved, April 29, 2014, from

http://chestofbooks.com/crafts/machinery/Shop-Practice-V1/Face-Milling-

Cutters.html#.U1-zkYGSx8E

Up Milling and Down Milling [Web Graphic]. Retrieved, April 29, 2014, from

http://www.mfg.mtu.edu/cyberman/machining/trad/milling/

Vernier Calliper [Web Graphic]. Retrieved, April 3, 2014, from

http://ecx.images-amazon.com/images/I/61dvgTmvXiL.jpg

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