bearing Assembly and Disassembly machine design

Design of Bearing Assembly and Disassembly Machine

BEARING ASSEMBLY & DISASSEMBLY MACHINE DESIGN DESIGNED BY MAEREG AMBELU 4th year mechanical engineering student in Addis Ababa University August 2012

Designed by: Maereg Ambelu

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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.

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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


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Design of Bearing Assembly and Disassembly Machine 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 Designed by: Maereg Ambelu

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Design of Bearing Assembly and Disassembly Machine 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


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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.

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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.

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Design of Bearing Assembly and Disassembly Machine 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. So, to overcome such and forth loss, just like bench vice, some other

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 Page 1

Design of Bearing Assembly and Disassembly Machine 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 Specification The above proposal presents the background for this case study involving an extractor. This Designed by: Maereg Ambelu

assembling and disassembling machine as shown in the figure 1, is going to be designed. In this design the design of Page 1

Design of Bearing Assembly and Disassembly Machine the main power screw and intermediate components are presented taking in to account the other bolts as necessary and standard.

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

A subset of the pertinent design specifications that will be needed for the design of this machine are given here.

Maximum height of the power screw………. 500mm.

Geometry Analysis The 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 Designed by: Maereg Ambelu

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 Page 1

Design of Bearing Assembly and Disassembly Machine 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

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

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


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 Page 1

Design of Bearing Assembly and Disassembly Machine Where, F

force on the nut

F = applied force 2 = 600N+2000N

Figure 4 lowering the load

=20,600N Where PR= Rising load PL = Lowering load

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

FN = friction force N = Normal force =lead angle = Vertical distance for one turn

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

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. ∑






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Design of Bearing Assembly and Disassembly Machine ∑





(

This is formula for rising load ∑

( 



∑





After manipulating the above two equations and solving for the raising and lowering loads (L) I can reach at ) (

)

(

For Raising Load

))

From the above equations the torque required for lowering the load is then given by;

This formula for lowering load

(

(

)

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

)

And (⁄

*

( ⁄

)+ )

If we divide it by

, we will get;

Torque is the product of force P and mean radius

, so it becomes; (

Then to check this we need to follow the iteration. )

Iteration

#1.

For Lowering Load From the above equation the torque required for lowering the load is then;


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Some assumptions are take that can be changed as a result of the design.

=37.96Nm…………..ANS Calculation for lowering torque

Some of the assumptions are as follows;

(

f = 0.08

) (

F = 20.6KN known from force analysis

=11.567Nm……………ANS

P = 4mm standard (for 32mm major diameter)

Since TL is positive, the power screw is safe for self-locking. But, we need to know its efficiency.

From this we can calculate the following parameters;

Efficiency of the power screw

Calculation diameter

for

mean = =

= =30mm…………ANS

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

Calculation for load

,

is number of treads

=1x4mm =4mm…………………..ANS

Force Analysis on the Nut

Calculation for raising torque (

) (

)

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.

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=

F is the force that the power screw transfers on the nut. And it is calculated earlier as;

, where;-

Fpy= force on a single from the main power screw

pin

FPX=force on the single pin from the auxiliary power screw.

But, from the body diagram drawn above, force exerted by the nut ( ) is known as;

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

Force Analysis on the Connecting Rod There are four connecting rods that are connected on the two slots

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.

(

)

= (

)

=16.609Nm 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:-

Lowering torque

(

d=28mm

) (

f=0.08 p=2.5mm F=10.3KN

Efficiency of the power screw

Dm= 28-3.5/2 =26.25mm

=

L=1*p =1*3.5mm = =3.5mm

Pushing torque

, which is safe


Stress Analysis Stress analysis on the main power screw We have: The axial nominal stress 

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.

The bearing stress

There are different stresses that we have to calculate. Body shear stresses This may occur as a result of raising torque



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;

Then to check for the factor of safety (n), we follow the following procedure.

Safety factor for the principal stress (np)

Maximum Principal Stress

√

Safe

Safety factor for shear stress (ns) ⁄

⁄

√

Which is safe

Maximum shear stress √

√

Stress analysis on the nut For standard square threads the depth or thickness of the tread is;


We have;

Then the factor of safety will be

Number of tread (n) is calculated as; It is economically better to fail the nut before the screw.

Stress analysis on auxiliary power screw

the

We have:

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

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.

The thread root bending stress

Body shear stresses This may occur as a result of raising torque,



Now to calculate the permissible bending stress and shear stress let’s consider the above stresses in plane of action as;

The axial nominal stress 

Maximum Principal Stress The bearing stress √

√


Safe

Maximum shear stress

Safety factor for shear stress (ns)

√

⁄

√ ⁄

Then to check for the factor of safety (n)

Which is safe So we can conclude with this result is that;

Safety factor for the principal stress (np)

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 Description Shaft diameter [mm] Bearing diameter [mm] Bearing width Static loading rating

Value 50.0 130.0mm 31.0mm 52000.0N

Bearing 6410, Single row ball From the previous calculation I have the following values with their description


Dynamic loading capacity Loads Radial force 20000.0N

Axial force 400.0N

87100.0N

Rating life 48.0

Results Description Equivalent static load [N] Equivalent dynamic load [N] Required static safety [-] Calculated static safety [-] Required rating life [mil. rev.] Calculated rating life [mil. rev.]

Value 20000.0N 20000.0N 1.0

Loads Radial force 5000.0

72.0

19.0 15000.0

30700.0

Axial force 600.0

Rating life 96.0

2.6 48.0 82.6

Bearing Life Determination On The Slots Bearing 6404, Single row ball Description

Bearing diameter [mm] Bearing width [mm] Static loading rating [N] Dynamic loading capacity [N]

Value Shaft diameter [mm]

20.0

Results Description Equivalent static load [N] Equivalent dynamic load [N] Required static safety [-] Calculated static safety [-] Required rating life [mil. rev.] Calculated rating life [mil. rev.]

Value 5000.0 5000.0 1.2 3.0 96.0 199.1


Stress Analysis on the Connecting Rod We have:Material selection

steel

Length (l)

170mm

Yield Stress

516.8MPa

Young’s modulus (ε) Width

50mm

Thickness

8mm

207GPa

The maximum resultant load (F) it carry is=√

This is an Bending assumption from materials found on market

Moment Stress ( )

Factor of safety

=5.337KN In order to overcome buckling we have to check its factor of safety. To do this; Moment of inertia (I)

Cost Analysis


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.

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)

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 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.

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

The added value 25 is the down time that may appear. Then the labor cost (LC)

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

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

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;

For professional and skilled machine man it took from 17munite up to 27 minute. Let’s take the maximum. Then;

Then the labor cost is by considering the following main points. Chamfering on the lath machine The added value 5 is the down time that may appear.

Cutting in the dimension using power saw

Then the labor cost (LC)

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)

Then the total cost (TC) on this pat is


The added value 15 is the down time that may appear and the multiplier 8 is the repetition of the part. Then the labor cost (LC)

Then the labor cost is by considering the following main points. Chamfering on the lath machine Cutting in the dimension using power saw Drilling using 20mm drill bit on a drill machine To do this all a professional machine man can perform it within 28 minutes. So, the total time (Tt)


The added value 8 is the down time that may appear and the multiplier 4 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;

Then the labor cost (LC)



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;



Then the labor cost is by considering the following main points. Chamfering on the lath machine Cutting in the dimension using power saw Drilling using 20mm drill bit on a drill machine To do this all a professional machine man can perform it within 28 minutes. So, the total time (Tt)

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;


Then the labor cost is by considering the following main points.


Chamfering on the lath machine Cutting in the dimension using power saw Making a gripping jaw through the middle in a direction of the 40mm side. To do this all, a professional machine man can perform it within 48 minutes. So, the total time (Tt)

Components


The other standard components cost analysis Site1 Site2 Site3 Site4

Main power screw Auxiliary power screw Main bearing

121.70 51.35

121.70 51.35

121.70 51.35

121.70 51.35

699.25

-

-

1243.65

Auxiliary bearing

255.35

-

255.35

695.35

Cylindrical pin 20 35 M10 bolt & nut

21.0

21.0

27.60

21.0

2.40

2.40

2.40

2.40


M12 bolt & nut

3.40

3.40

3.40

3.40

Cylindrical pin 20 310 Stud

74.45

74.45

74.45

74.45

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

Auxiliary power screw

Standard

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

121.70 Manufactured

158.75

Supporting frame

Manufactured

367.70

Basement

Manufactured

74.90

Connecting rod

Manufactured

172.90

Main guide

Manufactured

69.35


Sliding slot

Manufactured

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

113.00

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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