bearing Assembly and Disassembly machine design

Design of Bearing Assembly and Disassembly Machine

Designed by: Maereg Ambelu Page 0

BEARING

ASSEMBLY & DISASSEMBLY

MACHINE DESIGN

DESIGNED BY

MAEREG AMBELU 4th year mechanical engineering student in

Addis Ababa University

August 2012



ACKNOWLEDGEMENT

My mentor /Super visor at school/ Dr.

Ing. Birhanu Beshah advised me to

continue in this design as part of a

wider institute to raise an awareness of

my academic awareness in to practice.

I always want to thank you in

developing my language, knowledge

and cultivating me to make reading is

to be my hobby.

I consulted many people in many

sector of the company. It is impossible

to thank them all individually but I

would like to note here their

contributions of ideas, manuals and

contacts are greatly appreciated.

Colleagues at BGI have shared

their expertise on particular sectors

and areas of machine and mechanical

Engineering fields. My special thanks

go to the two bottling department

managers, Eng. kirubel W/hawariat

and Eng. Tamirat Seid for their

willingness in accepting my endless

questions and provide every supportive

materials and ideas.

I also would like to thank the shift

leaders in bottling department

mentioning their name like, biruk

ketema and Melaku Teshome. And

from mechanics Yalew Getachew for

their skill and patience, and W/ro

Mame, workshop boss for her

motherly treatment.

My particular thanks goes to my

friend ENDALKACHEW TAYE, who

were helping me in every editorial of

modeling’s that as I want in every time

for every modelings that will help me

through this design and for internet

access to down load some helpful

pictures and videos.



Contents ACKNOWLEDGEMENT ................................................................................................................................... 0

INTRODUCTION ............................................................................................................................................. 1

The Reason Why this Design Is Important .................................................................................................... 0

What Makes It Innovative and Different ...................................................................................................... 1

1. IT’S BILATERAL FUNCTION ................................................................................................................ 1

2. ONE FOR ALL TYPES OF BEARING ...................................................................................................... 1

4. SIMPLICITY ........................................................................................................................................ 1

Disadvantage of this Machine ...................................................................................................................... 1

Problem Specification ................................................................................................................................... 1

Geometry Analysis ........................................................................................................................................ 1

Force Analysis ............................................................................................................................................... 1

Force Analysis on the power screw .......................................................................................................... 1

Free body diagram of over the entire machine is as sketched and seen below:- .................................... 1

Square threaded ....................................................................................................................................... 1

Single thread ............................................................................................................................................. 1

For Raising Load ........................................................................................................................................ 2

For Lowering Load ..................................................................................................................................... 2

Iteration #1. .............................................................................................................................................. 2

Calculation for mean diameter ................................................................................................................. 3

Force Analysis on the Nut ............................................................................................................................. 3

Force Analysis on the Connecting Rod.......................................................................................................... 4

Force analysis on the auxiliary power screw ................................................................................................ 4

Pushing torque .......................................................................................................................................... 5

Lowering torque .................................................................................................................................... 5

Efficiency of the power screw ................................................................................................................... 5

Stress Analysis .............................................................................................................................................. 6

Stress analysis on the main power screw ................................................................................................. 6

Material selected; ..................................................................................................................................... 6

Body shear stresses ............................................................................................................................... 6



The axial nominal stress ........................................................................................................................ 6

The bearing stress ................................................................................................................................. 6

The tread root bending stress ................................................................................................................ 6

Maximum Principal Stress ........................................................................................................................ 7

Maximum shear stress .............................................................................................................................. 7

Safety factor for the principal stress (np) .................................................................................................. 7

Safety factor for shear stress (ns) .............................................................................................................. 7

Stress analysis on the nut ......................................................................................................................... 7

Material selection ..................................................................................................................................... 8

Stress analysis on the auxiliary power screw ............................................................................................ 8

Material selected; ..................................................................................................................................... 8

Body shear stresses ............................................................................................................................... 9

The axial nominal stress ........................................................................................................................ 9

The bearing stress ................................................................................................................................. 9

The thread root bending stress............................................................................................................. 9

Maximum Principal Stress ........................................................................................................................ 9

Maximum shear stress ............................................................................................................................ 10

Safety factor for the principal stress (np) ................................................................................................ 10

Safety factor for shear stress (ns) ............................................................................................................ 10

Bearing life Determination on the main power screw ........................................................................... 10

Description .......................................................................................................................................... 10

Loads ................................................................................................................................................... 11

Results ................................................................................................................................................. 11

Bearing Life Determination ................................................................................................................ 11

On The Slots ....................................................................................................................................... 11

Description .......................................................................................................................................... 11

Loads ................................................................................................................................................... 11

Results ................................................................................................................................................. 11

Stress Analysis on the Connecting Rod ................................................................................................... 12

Moment of inertia (I) .......................................................................................................................... 12

Bending Moment Stress ( ) .................................................................................................................... 12

Factor of safety ................................................................................................................................... 12



Cost Analysis ............................................................................................................................................... 12

Basic assumption .................................................................................................................................... 13

Machining coast for the supporting frame ......................................................................................... 13

Material & machining cost of the basement ...................................................................................... 14

Manufacturing cost for Connecting rod ............................................................................................. 15

Manufacturing cost for Sliding slot ..................................................................................................... 16

The main guiding ................................................................................................................................. 17

Jaw Plat Welded On The Auxiliary Power Screw ................................................................................ 17

The other standard components cost analysis.................................................................................... 18

Assembly Cost ......................................................................................................................................... 20

Total cost..................................................................................................................................................... 20

Part drawing ................................................................................................................................................ 21

Assembly Drawing ....................................................................................................................................... 22

Reference:- .................................................................................................................................................. 22



INTRODUCTION

Assembling and disassembling of

bearings, gears, shaft couplers and

other force fit components that can

be disassembled is one of the most

common machine tasks. An efficient

means of disassembling was

through EXTRATER (sometimes

called PULLER). But there is

nothing about assembling those

components on a shaft except

hammering and using press

machine which is not always

available. Particularly for bearing,

a modernized machine called FAG

heater is used. It is used only for

assembling bearings. Simply

heating the bore circumference of

the bearing until it expands. When

it expands, it will be assembled and

left to cool and contract. But it is

quite expensive as well as it took

large area as a result it is not easy

in different working areas. In

addition to this it requires five

phase electric power input. So its

electric consumption is also high.

The design of a system to assemble

and disassemble those components

requires attention to this design and

selection of individual components

like bolts, nuts, power screw,

welding strength, the supporting

frame, etc… However as is often,

the case in design, those

components are not independent.

For example, in order to design the

supporting frame for stress and

deflection, it is necessary to know

the applied force. If the forces are

transmitted to the supporting

frame, it is no surprise that the

design process is interdependent

and iterative. But the point is where

should I start this design?

It was my intention to design to

design for maximum and minimum

bearing found only in BGI

ETHIOPIA Company, a place

where I held my apparent ship, but

I widened my sight to be a standard

and applicable for any company

with any bearing dimensions. So, I

used SKF bearing table from the

minimum to maximum bearing

type with bore diameter, width and

hub diameter.



The Reason Why this Design Is Important In BGI ETHIOPIA, SAINT

GOERGE BREWERY Company,

in the organizational category of

maintenance, there are two main

maintenance sections, the bottling

section and utility section. In utility

section there are different gear

boxes, pumps, compressors, motors,

and etc… that are maintained. On

average minimum of two of the

listed items above are maintained.

In maintaining this, they use

extractor to pull out the force fit

components. But assembling is by

using hammer or they took it to the

work shop and use a press machine.

Luckily in this section, they have a

FAG heater machine that I tried to

introduce. Its working principle is

by using a magnetic heater. A

magnetic part is putted on the inner

diameter of the bearing and heated.

This is just to expand the hub

diameter of the bearing to ease the

assemblage.

In bottling section, they use the

same technique for disassembling

as those of the utility section.

However, in the process of assembly

they took it to the work shop and

use a press machine. But from the

bottling section the work shop is too

far away. Those weighing shafts are

taken to the work shop by man

power. Also the reader should

observe the time wastage and

downtime created on the

production.

Not only this, there are extensions

used while assembling to cover the

gap between piston coming from

pressing machine and the shaft

holding the bearing(s). They kill

their time searching for pipes in

metal shop with the probability that

the dimension of the hub diameter

of the bearing in order to cover that

gap because there is no standard

with the pressing machine.

After they are successful in

searching the pipe in a dimension,

then, someone is going to hold the

pipe and the other is to hold the

shaft beneath the working table of

the press machine. So, three peoples

are going to participate in

assembling on press machine, of

course it may cause injury on

human’s body.



So, to overcome such and forth loss,

just like bench vice, some other

technique must be putted. That is

what must do a combination job of

the pressing machine and the

extractor used for disassembly. This

is the problem that my design is

going to solve more systematically

and that minimize labor.

What Makes It Innovative and Different The difference between my design

and commonly used extractors (puller)

is listed as follows:-

1. IT’S BILATERAL FUNCTION

I tried to search on line on an

internet to check whether the machine

that can perform both assembly and

disassembly of force fitted machine

components. But I found no extractor

or simple machine that can perform

assembly and disassembly.

So I am confident enough to say it is

innovative and that is what makes it

innovative and can assemble and

disassemble those force fitted machine

components.

2. ONE FOR ALL TYPES OF

BEARING

It took the advantage

over extractor in that with

the variable dimension of

the bearing we are going to

disassemble, we need an

extractor varying in

dimension too. But this

design can overcome having

sets of this variety of

extractors (pullers).

3. SAVES COST

Think of the cost we are going to

buy this sets of extractor. Even if

I am not sure about standard,

but I found one set of extractor

holds eight (8) extracts. But this

machine can perform all in one.

So, the cost for one simple

machine will be much more less

eight extractors. From this angle

the reader may conclude the



design is innovative and

different

4. SIMPLICITY

Observe a man when he extracts a

bearing, he use a bench vice to grip it

at first. Then he brings 17 numbered

wrench for smaller and Adjustment

(adjustable wrench) for larger

extractors. A man working on this new

machine does not require another

person. This is because the slots on the

supporting frame are used to adjust

according to the shaft height and

bearing, gear, coupler, etc… diameter

and the gripper will grip the shaft just

by applying a minimum torque on the

arm. There is also bearing roll on the

slot provide that used to reduce

friction.

Here, this design reduces

wrenches, spacers, using hammer,

labors, etc… in both case of

assembling and disassembling. This is

also another quality and invention.

Disadvantage of this Machine But, as there is innovation and

an advantage over the present

machines, there is also a disadvantage

with this machine. It doesn’t

disassemble and assemble force fit

components in to the housing. Its

purpose is only for force fitted

machine components on a shaft.

But when I try to put this as a

disadvantage, I didn’t mean that the

extractors have the ability to

disassemble those mechanical

components. That is not the case,

because the extractors couldn’t

disassemble bearings and other force

fitted components from the housing. In

such cases, bearing, gears, etc… are

disassembled by using hammer. This

may be overcome by some other

innovative design in the future.

Problem SpecificationThe above proposal presents the

background for this case study

involving an extractor. This

assembling and disassembling machine

as shown in the figure 1, is going to be

designed. In this design the design of



the main power screw and

intermediate components are

presented taking in to account the

other bolts as necessary and standard.

A subset of the pertinent design

specifications that will be needed for

the design of this machine are given

here.

Maximum design load the power screw

applied on the

gripper……………20KN

Minimum force fit holding shaft’s

length….150mm

Maximum force fitted components

diameter……..….320mm

Maximum height of the assembly and

disassembly machine from the surface

of the table......................900mm

Maximum height of the power

screw………. 500mm.

Geometry AnalysisThe supporting frame has a slot

on both sides. As I said previously the

purpose of the two slots is that to move

up and down the two grippers. When

those grippers are joined, they form a

hole of the top view rhombus which

gives easy gripping mechanism. At the

two end of the gripper there is a bolt to

create a gap for the shaft. Since the

gap between the two grippers must be

at least the maximum bearing

diameter, it should be 320mm with

some clearance of 20mm for putting

bearing easily. And the slot is with

20mm diameter. Because to be strong

enough I may use17mm pitch diameter

screw. There is also caliper used to clip

the two grippers with the main nut.

The distance between the gripper is

varying as different bearings are used.

Then as the main power screw is

fastened, it pushes down the shaft and



the gripper pulled up by the clipper on

the washer. This is the overall machine

geometry with the assumed dimension.

Force Analysis

Let’s look at the skeletal machine

component to be designed.

Force Analysis on the power

screw

Free body diagram of over the

entire machine is as sketched and seen

below:-

Let’s assume one can apply a

force of 600N on the arm of length of

300mm. let’s assume also 400N for the

sides and 200mm arm length.

F is known that it is the maximum

design load and the effort that the

shaft of the bearing can apply, that is

20KN+600N=20600N.

Rotating the arm in a length , it will

cause moment (M) on the power screw.

As we know moment is given by the

formula

Figure 2 force diagram of the power

screw

Considering summation of force

on the y direction to be positive, that is

∑Fy=0, to be positive



Where,

F force on the nut

F = applied force

2

= 600N+2000N

=20,600N

The figure above is some portion

of the power screw. It is important

here to specify my power screw type.

My screw is of the type

Square threaded

Single thread For my design I must prove the

lowering and rising Torque is safe to

pull out and assemble the bearing. To

do this, I must do a force analysis on a

single tread, which looks as follow,

Figure 3 lifting the load

Figure 4 lowering the load

Where PR= Rising load

PL = Lowering load

FN = friction force

N = Normal force

=lead angle

= Vertical distance for one turn

On the above figure imagine that a

single thread of screw is unrolled or

developed, exactly for one turn. Then

one edge of the thread will form the

hypotenuse of aright triangle whose

base is the circumference of the mean

diameter and whose head is lead. I

tried to represent all summation of the

force on the power screw to be F.

Then, In order to make the system in

equilibrium for raising the load, and

lowering the load, the following

equations must be satisfied.

∑



∑

This is formula for rising load

∑

∑

This formula for lowering load

For Raising Load

After manipulating the above two

equations and solving for the raising

and lowering loads (L) I can reach at

(

)

(

)

And

* ( ⁄ )+

(

⁄ )

Torque is the product of force P and

mean radius

, so it becomes;

(

)

For Lowering Load From the above equation the torque

required for lowering the load is then;

( (

))

(

)

From the above equations the torque

required for lowering the load is then

given by;

(

)

This torque is required to overcome a

part of friction in lowering the load.

We should have to be careful with NO

NEGATIVE torque.

Especially in lowering torque, if the TL

is positive our power has good self

lock. In order not to get a negative T L,

we have to check that

If we divide it by , we will get;

Then to check this we need to follow

the iteration.

Iteration #1.


Some assumptions are take that can

be changed as a result of the design.

Some of the assumptions are as

follows;

f = 0.08

F = 20.6KN known from force

analysis

P = 4mm standard (for 32mm

major diameter)

From this we can calculate the

following parameters;

Calculation for mean

diameter

=

=30mm…………ANS

Calculation for load

, is number of treads

=1x4mm

=4mm…………………..ANS

Calculation for raising torque

(

)

(

)

=37.96Nm…………..ANS

Calculation for lowering torque

(

)

(

)

=11.567Nm……………ANS

Since TL is positive, the power

screw is safe for self-locking. But,

we need to know its efficiency.

Efficiency of the power screw

=

=

=34.54%.............ANS

Force Analysis on the

Nut The aim of this design is to

overcome labor force. In doing so,


rather than the nut to roll over the

supporting frame with a large

friction, I assumed to used bearing

in order to ignore frictional force

(Ff) created at the contact between

the nut and the supporting frame.

F is the force that the power screw

transfers on the nut. And it is

calculated earlier as;

But, from the body diagram drawn

above, force exerted by the nut ( )

is known as;

Force Analysis on the

Connecting Rod There are four connecting rods that

are connected on the two slots

prepared on the nut by a pin

through a bearing. Here there are

four pines that share the force

equally, since they are symmetry to

each other. That is;

Fpy=

, where;-

Fpy= force on a single pin

from the main power screw

FPX=force on the single pin from the

auxiliary power screw.

If we disassemble this linkage, we

will get from the force analysis of

the auxiliary power screw, the

horizontal force that is applied by

the person may be 400N. So, that is

applied on t he pin is 1400N (this

will be calculated later on).

Force analysis on the

auxiliary power screw The machine uses two auxiliary

power screws with a jaw, used to

grip shaft and bearing from the left

and right. From one side assume

that a person may apply a

maximum effort of 400N.

∑


Where, Fs denote force applied by

supporting frame.

The reason of the coefficient 2 is

that there are two supporting frame

which are symmetric to each other.

NOTE THAT; the jaw is assumed

to apply a force of 1000N. In order

to overcome failure of self locking,

let’s check using some assumption

from the standard. They are:-

d=28mm

f=0.08

p=2.5mm

F=10.3KN

Dm= 28-3.5/2

=26.25mm

L=1*p

=1*3.5mm

=3.5mm

Pushing torque

(

)

=

(

)

=16.609Nm

Lowering torque

(

)

(

)

Efficiency of the power screw

=

=

, which is safe


Stress Analysis

Stress analysis on the main power screw

We have:

ηf and

unsupported length is 450mm.

Material selected; Steel bolt with low or medium

carbon of SEA grade number is

selected. The selection is based on

the material availability and cost of

material.

There are different stresses that we

have to calculate.

Body shear stresses

This may occur as a result of raising

torque

The axial nominal stress

The bearing stress

The tread root bending stress


Now to calculate the permissible

bending stress and shear stress let’s

consider the above stresses in plane

of action as;

Maximum Principal Stress

√

√

Maximum shear stress

√

√

Then to check for the factor of

safety (n), we follow the following

procedure.

Safety factor for the principal

stress (np)

Safe

Safety factor for shear stress

(ns)

⁄

⁄

Which is safe

Stress analysis on the nut For standard square threads the

depth or thickness of the tread is;


We have;

Number of tread (n) is calculated

as;

Material selection Bronze is not strong as steel. Silicon

bronze that is Cu=95%, Si=4% and

Mn=1%, is quite good for making

nut and also it is the one that one

can found on market very easily. It

is also available in wrought

condition with a yield stress of

660MPa.

For the selected material let’s check

its factor of safety

Then the factor of safety will be

It is economically better to fail the

nut before the screw.

Stress analysis on the

auxiliary power screw We have:

ηf and

unsupported length is 450mm.

Material selected; Steel bolt with low or medium

carbon of SEA grade number is

selected. The selection is based on

the material availability and cost of

material.


There are different stresses that we

have to calculate.

Body shear stresses

This may occur as a result of

raising torque,

The axial nominal stress

The bearing stress

The thread root bending stress

Now to calculate the permissible

bending stress and shear stress let’s

consider the above stresses in plane of

action as;

Maximum Principal Stress

√

√


Maximum shear stress

√

√

Then to check for the factor of

safety (n)

Safety factor for the principal

stress (np)

Safe

Safety factor for shear stress

(ns)

⁄

⁄

Which is

safe

So we can conclude with this result

is that;

D=30mm

P=3.5mm

Dm=28.25mm

Dr=26.5mm

Bearing life Determination on the main power screw From the calculation the bearing

type that is found in the market is

of the type

Description

Bearing 6410, Single row ball

From the previous calculation I

have the following values with their

description

Description Value

Shaft diameter [mm] 50.0

Bearing diameter [mm] 130.0mm

Bearing width 31.0mm

Static loading rating 52000.0N


Dynamic loading capacity 87100.0N

Loads

Radial

force

Axial

force

Rating

life

20000.0N 400.0N 48.0

Results

Description Value

Equivalent static

load [N]

20000.0N

Equivalent

dynamic load [N]

20000.0N

Required static

safety [-]

1.0

Calculated static

safety [-]

2.6

Required rating life

[mil. rev.]

48.0

Calculated rating

life [mil. rev.]

82.6

Bearing Life Determination

On The Slots

Bearing 6404, Single row ball

Description Value

Shaft

diameter

[mm]

20.0

Bearing

diameter

[mm]

72.0

Bearing

width [mm]

19.0

Static

loading

rating [N]

15000.0

Dynamic

loading

capacity [N]

30700.0

Loads

Radial

force

Axial

force

Rating

life

5000.0 600.0 96.0

Results

Description Value

Equivalent static load

[N]

5000.0

Equivalent dynamic

load [N]

5000.0

Required static safety

[-]

1.2

Calculated static

safety [-]

3.0

Required rating life

[mil. rev.]

96.0

Calculated rating life

[mil. rev.]

199.1


Stress Analysis on the Connecting Rod We have:-

Material selection steel

Length (l) 170mm

Yield Stress 516.8MPa

Young’s modulus (ε) 207GPa

Width 50mm

Thickness 8mm

The maximum resultant load (F) it

carry is=√

=5.337KN

In order to overcome buckling we

have to check its factor of safety. To

do this;

Moment of inertia (I)

Bending Moment Stress ( )

Factor of safety

Cost Analysis

This is an

assumption

from materials

found on

market


Basic assumption Since BGI is international brewery

company and have 52 branches all

over the company, I assumed its

payroll is also standard and

international.

Per month, the payment is to be

assumed for mechanic 4,872.15 ETH

Working hour per month is 192hr

from data taken from the company in

Ethiopia.

Machining coast for the supporting

frame

8mm sheet steel metal price costs

16birr per kilogram and one kilogram

is 200mm by 200mm. this design uses

two supporting frame which are

900mm by360mm.

Its price is then, can be estimated

based on the following points.

If the price for 20cm by 20cm is

16birr, what will be the price for

36cm by 90cm is the question. To

solve this;

Cost for 36by90

The supporting frames machining

cost is then can be calculated as; the

supporting frame is manufactured

machining from a sheet steel of 8mm

thickness. The necessary future are

cutting the metal in to the necessary

dimensions then chamfering on a lath

machine. After that, making a slot on

a lath machine is followed.

For a professional and very skilled

machinist it may take from 20 to 30

minute. If we take the maximum one,

the total labor cost for this part is

then;

The added value 5 is the down time

that may appear.

Then the labor cost (LC)

The supporting frame must be welded

with the basement. So, it requires cost


estimation. To weld those components

It is better if ARC WELDING

TECHNOLOGY is selected, because

of its low price related with the TIG

welding technology. So using this

technology a professional welder may

finish the task within three hours.

According to my assumption, BGI

ETHIOPIA,s payroll for employee,

for a welder the payment is 3228.15

birr.


that may appear.


As the professional told me after I

show him the welded parts dimension,

about 25 up to 30 electrodes may be

required.

On the market one electrode costs

(EC) 2.75birr that can weld a radius

of 2.4mm. So its cost can be calculated

as;

There are costs that can’t be

estimated like electric power logistics.

This can be added with some

percentile.

Then the total cost (TC) on this pat is

Material & machining cost of the

basement

There is only one basement with a

dimension of 360mm by 426mm. the

material cost is then;

Then the labor cost is by considering

the following main points.


It is manufactured by taking the

sample from the sheet metal by

considering;

Facing on the lath machine

Drilling by 10mm drill bit to make

four holes

Chamfering all the edges

For professional and skilled machine

man it took from 17munite up to 27

minute. Let’s take the maximum.

Then;


that may appear.



Manufacturing cost for Connecting

rod

There are eight connecting rod on

each having two 20mm diameter hole

with a dimension of 195mm by 50mm.

the material cost is then;



Chamfering on the lath machine

Cutting in the dimension using power

saw

Drilling using 20mm drill bit on a

drill machine

Preparing semi circle of 50 diameter

at the end

To do this all a professional machine

man can perform it within 40

minutes. So, the total time (Tt)



that may appear and the multiplier 8

is the repetition of the part.



Manufacturing cost for Sliding slot

There are four sliding slot on each

having two 20mm diameter slots with

a dimension of two sides with 82mm

by 160mm and 16mm by160mm. The

material cost is then;





saw


drill machine










The main guiding

There are four guiding slot on each

with a dimension of two sides with

12mm by 700mm by5mm and one

30mm by700mm. The material cost is

then;





saw


drill machine









Jaw Plat Welded On The Auxiliary

Power Screw

There are two jaws that are welded on

the auxiliary power screw with a

dimension of 170mm by40mm but it is

different from the other in its

thickness that is 12mm. and the cost is

16birr per kilogram which is 15mmby

15mm. The material cost is then;






saw

Making a gripping jaw through the

middle in a direction of the 40mm

side.

To do this all, a professional machine








The other standard components cost analysis

Components Site1 Site2 Site3 Site4

Main power screw 121.70 121.70 121.70 121.70

Auxiliary power

screw

51.35 51.35 51.35 51.35

Main bearing 699.25 - - 1243.65

Auxiliary bearing 255.35 - 255.35 695.35

Cylindrical pin

20 35

21.0 21.0 27.60 21.0

M10 bolt & nut 2.40 2.40 2.40 2.40


M12 bolt & nut 3.40 3.40 3.40 3.40

Cylindrical pin

20 310

74.45 74.45 74.45 74.45

Stud 8.55 8.55 8.55 8.55

The overall machine cost analysis is summarized in this table.

Components Standard Manufactured Total cost

Main power screw Standard 121.70

Auxiliary power

screw

Standard Manufactured 158.75

Main bearing Standard 699.25

Auxiliary bearing Standard 2042.80

Cylindrical pin Standard 252

Cylindrical pin Standard 148.90

M10 bolt&nut Standard 9.60

M12 bolt& nut Standard 6.80

Supporting frame Manufactured 367.70

Basement Manufactured 74.90

Connecting rod Manufactured 172.90

Main guide Manufactured 69.35


Sliding slot Manufactured 113.00

Assembly Cost Some parts like the pins requires

force fitting which are 12in number

and 8 bearing must be force fitted

with the pins in order to roll it easily.

Then we have about 20 force fitted

components. After this, there should

have to be a table to be drilled at four

holes. Up to this it may require up to

seven hours including some

machining required assume nine

hours. Then if the assemblers

payment is 3500birr, then

Total cost The sum of material cost and labor

cost is as shown on the table below:

Components Total cost

Main power screw 121.70

Auxiliary power screw 158.75

Main bearing 699.25

Auxiliary bearing 2042.80

Cylindrical pin 252

Stud 148.90


M10 bolt 9.60

M10 nut 6.80

Supporting frame 367.70

Basement 74.90

Connecting rod 172.90

Main guide 69.35

Sliding slot 113.00

Electric power cost (15% of the

manufacturing cost)

127.75

Profit a company may gain (15%) 633.80

Final cost 4859.20

Part drawing


Assembly Drawing

Reference:- 1. Mechanical engineering design; Shigly; ninth edition

2. Machine element design; Robert Mott.; fourth edition

3. Design of machine element, an integrated approach

bearing Assembly and Disassembly machine design

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