Post on 02-Jun-2018
8/11/2019 522 My Project Isa
1/14
THE AMERICAN UNIVERSITY IN CAIRODepartment of Mechanical Engineering
MENG 522Materials in Design and Manufacturing
Project
Dr. Amal Essawi
By:
Dina Fouad 900-07-0841
8/11/2019 522 My Project Isa
2/14
P a g e | 2
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.
8/11/2019 522 My Project Isa
3/14
P a g e | 3
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
8/11/2019 522 My Project Isa
4/14
P a g e | 4
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.
8/11/2019 522 My Project Isa
5/14
P a g e | 5
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.
8/11/2019 522 My Project Isa
6/14
P a g e | 6
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
8/11/2019 522 My Project Isa
7/14
P a g e | 7
- 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)
8/11/2019 522 My Project Isa
8/14
P a g e | 8
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.
8/11/2019 522 My Project Isa
9/14
P a g e | 9
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
8/11/2019 522 My Project Isa
10/14
P a g e | 10
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
8/11/2019 522 My Project Isa
11/14
P a g e | 11
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
8/11/2019 522 My Project Isa
12/14
P a g e | 12
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.
8/11/2019 522 My Project Isa
13/14
P a g e | 13
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.
8/11/2019 522 My Project Isa
14/14
P a g e | 14
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