522 My Project Isa

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THE AMERICAN UNIVERSITY IN CAIRODepartment of Mechanical Engineering

MENG 522Materials in Design and Manufacturing

Project

Dr. Amal Essawi

By:

Dina Fouad 900-07-0841


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AbstractIn this report, Design for Assembly (DFA) is being examined on two different versions of the

same product. A Hair dryer is selected in order to assess and apply DFA concepts. All results are

discussed in order to examine the evolution of design for assembly and manufacturing.


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Contents

Abstract .................................................................................................................................................. 2

Objectives .............................................................................................................................................. 4

Introduction- DFA ................................................................................................................................. 5

Products used and their components ...................................................................................................... 6

Assembly Procedure for the Braun hair dryer (1985) ............................................................................ 8

Assembly Procedure for the Kenwood hair dryer (2005) ...................................................................... 9

Section 1: Design for Assembly Worksheet ........................................................................................ 10

Old Braun Hair Dryer .................................................................................................................. 10

New Kenwood Hair Dryer ............................................................................................................... 10

Section 2: Handling and Insertion ........................................................................................................ 11

Braun hair Dryer .............................................................................................................................. 11

Kenwood Hair Dryer........................................................................................................................ 11

Discussion ............................................................................................................................................ 12

Part I ................................................................................................................................................. 12

Part II ............................................................................................................................................... 13

Conclusion ........................................................................................................................................... 14


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Objectives1- Select two versions of a consumer product having the same working principle.

2- Dissemble the product.

3- Reassemble while recording time taken.

4-

Notice any difficulties occurring while reassembling.

5- Prepare DFA worksheets for analyses.

6-

Compare and discuss the actual time taken and the time expected to take to

7- Reassemble according to the DFA and time standards.

8-

Compare the two designs together.

9- Discuss noticeable improvements in the design.


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Introduction- DFA

"Design for assembly" (or DFA) means the design of the product for ease of assembly .Design for

manufacturing and assembly is a relatively new approach, It is a procedure in order to examine all

manufactured product with the goal to simplify its manufacturing, assembly, which will lead to a

cost reduction. This increases efficiency to a great extent. It also improves the quality of products

and reduces the number of used parts in the assembly process DFA allows several disciplines in

engineering to interact together rather than have the one wall approach. DFA provides a more

organized way of thinking when designing which leaves a small room for error; it results to simpler,

more efficient designs and more users friendly. However, like any approach DFA has some

disadvantages and cannot be done at all times. It requires time and effort that sometimes designers

dont have, and unless it is really justifiable and crucial no one would take the DFA approach.


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Products used and their components

- Old Product ( Braun Hair Dryer- 1985)

A) Components B) Tools used for Assembly and Disassembly

1- Front Chassis

2-

Back Chassis

3- Movable heat adjuster

4- Fan Cap protector5- Air outlet device

6- Wire and chassis holder ( 2 screws)

7- A small and large bolt

8- Motor9- Heating coil

10-Circuit


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- New Product ( Kenwood Hair Dryer- 2005)

A) Components B) Tools used for Assembly and Disassembly

1- Back Chassis

2- Front Chassis (with built in air guide & heatingcircuit )

3- Screws for motor & fan

4- Screws for the Chassis

5- Cap ( protector)6-

Motor & Fan

7-

Circuit for the switch on and off ( heat or Cool)


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Assembly Procedure for the Braun hair dryer (1985)

1.

Put the front chassis in position in order to

start the assembly process

2. Followed by manually inserting the fan

coupled with the circuit on top.

3. Carefully mount the circuit on the chassis by

inserting the holder and tightening the 2screws as shown

4. Put the heat adjuster and position it carefully.

5. Put the back chassis and position it

6. Insert the large bolt by means of a screw and

tighten it carefully to ensure the whole assembly is

in correct position.

7. Insert the air outlet device in between.

8. Then, by using a suitable screw, fasten the small

bolt into place to complete assembly.

9. Place the cap at the back of the motor.


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Assembly Procedure for the Kenwood hair dryer (2005)

1.

Put the front chassis in position in order tostart the assembly process

2. Followed by manually inserting the fan

with the motor in position.

3. Carefully mount the on the chassis by

tightening the 2 screws as shown.

4. Manually place the back chassis on top.

5. To hold the two chassis together, tighten the 2

screws by the screw driver ( star shaped)

6. Place the cap at the back , it will immediately fit

and be in p


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Section 1: Design for Assembly Worksheet

Old Braun Hair Dryer

Step No.Type Theoretical Part

Count

Assembly Time Assembly Cost Total Cost

(Part/Subassembly) Sec $/Sec $

Front Chassis 1 Part 1 3 0.0083 0.025

Motor & circuit&

heating coil2 Part 2 20 0.0083 0.166

2 screws & holder 3 Part 0 60 0.0083 0.498Heat Adjuster 1 Part 1 50 0.0083 0.415

Air guide 1 Part 1 10 0.0083 0.083

Back Chassis 1 Part 1 4 0.0083 0.033

Chassis Small Screw 1 Part 0 3 0.0083 0.025

Cap 1 Part 1 8 0.0083 0.067

Sum 11 - 7 158 - 1.312

New Kenwood Hair Dryer

Step No.Type Theoretical Part

Count

Assembly Time Assembly Cost Total Cost

(Part/Subassembly) Sec $/Sec $

Front Chasis 1 Part 1 5 0.0083 0.0415

Align the Motor, Fan 1 Part 1 25 0.0083 0.2075

2 screws 2 Part 0 25 0.0083 0.2075Back Chasis 1 Part 1 20 0.0083 0.166

2 screws 2 Part 0 30 0.0083 0.249

Cap 1 Part 1 3 0.0083 0.0249

Sum (Sec) 8 - 4 108 - 0.8964


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Section 2: Handling and Insertion

Braun hair Dryer

Step No.Handling

Code

Handling

Time/Item

Handling

Time/StepInsertion

Code

Insertion

Time/Item

Assembly

Time/Step

Total

Time/Step

Assembly

Cost

Total

Cost

Sec Sec Sec Sec Sec $/Sec $

Front Chassis 1 00 1.13 1.13 00 1.5 1.5 2.63 0.0083 0.0219

Motor & circuit&

heating coil2 05 1.84 1.84 08 6.5 6.5 8.34 0.0083 0.0692

2 screws & holder 3 04 2.18 6.54 06 5.5 16.5 23.04 0.0083 0.1912

Heat Adjuster 1 00 1.13 1.13 00 1.5 1.5 3.86 0.0083 0.0322

Air guide 1 00 1.13 1.13 30 2 2 3.13 0.0083 0.026

Back Chassis 1 00 1.13 1.13 06 5.5 5.5 7.3 0.0083 0.0608

Chassis Small Screw 1 04 2.18 2.18 00 1.5 1.5 3.68 0.0083 0.0305

Cap 1 03 1.69 1.69 30 2 2 3.69 0.0083 0.0306

Sum 11 - - - - - - 55.67 - 0.46

Kenwood Hair Dryer

StepN

o.

Handling

Code

Handling

Time/Item

Handling

Time/StepInsertion

Code

Insertion

Time/Item

Assembly

Time/Step

Total

Time/Step

Assembly

Cost

Total

Cost

Sec Sec Sec Sec Sec $/Sec $Front Chasis 1 00 1.13 1.13 00 1.5 1.5 2.63 0.0083 0.0219

Align the

Motor, Fan1 00 1.13 1.13 00 1.5 1.5 2.63 0.0083 0.0219

2 screws 2 04 2.18 4.36 06 5.5 11 15.36 0.0083 0.12748

Back Chasis 1 00 1.13 1.13 00 1.5 1.5 2.63 0.0083 0.0219

2 screws 2 04 2.18 4.36 06 5.5 11 15.36 0.0083 0.12748

Cap 1 03 1.69 1.69 30 2 2 3.69 0.0083 0.0306

Sum (Sec) 8 - - - - - - 42.3 - 0.35


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Discussion

Part I

After assembling both products, the Kenwood hair dryer was much better than the old braun

hair dryer in terms of the assembling and number or parts. One of the problems that was faced is

aligning the motor/fan part in to place in the chassis. This problem was solved into a better solutionin the new Kenwood hair dryer. As shown below, there is an aid piece that immediately fits into

place as you align, which ensures correct positioning.

Also the heat adjuster was removed in order to reduce the number of components that does not have

a major role and can be combined in design in terms of a circuit as a switch.

Designers may have used the DFA as there are some components that were completely

disregarded and combined with another. For example, in the figure below,

- A built in air guide is made into the inlet cavity of the front chassis.

There have been some modifications that have been applied to the hair dryers:

1-

Chassis has been changed.2-

Heat adjuster removed and is a switch.

3- Cover of the motor has been removed and encompassed well in the back chassis.

Taking all these modifications into account the Kenwood has improved in comparison to the old

Braun, which led to a drop in both the assembly time and cost.


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Part II

The theoretical time of assembling the Kenwood Hair Dryer has shown a decrease when

compared to the Braun Hair Dryer due to combining some parts together and removal of unnecessary

parts. New assembly time is 42 sec VS 55 sec & the assembly efficiency is 11.1 % as opposed to

only 13.2%. However looking at the big picture, as expected the actual assembly produced different

results, the new according to DFA should take about 42 seconds however in reality it took

108seconds. Practical assembly timing is higher value than that of a theoretical one. However, it can

be improved if the assembly procedure is repeated more than one time in order to ensure that the

required skill is attained before measuring the assembly time. As for the old hair dryer, DFA

predicted it would take 55 seconds for assembly while it actually took 158 seconds in reality. This

again is related to who assembles it and the amount of time the worker assembles the product that

they get the hang of it with experience and time and thus reducing some of the human errors and

unnecessary time wasting elements that a first timer would do.


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Conclusion

The most important thing that both the DFA and the actual assembly operation agree on and confirm

is that the new hair dryer was more efficient in assembling and took much less time which proves

how redesigning and taking into consideration other ways of securing components, materials, and

amount of components can result in better efficiency. This project confirmed how DFA is very

useful and effective in improving any designs efficiency as well as reducing the cost of

manufacturing of the product

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522 My Project Isa