FMEA Escova de Dentes
FMEA Escova de Dentes
FMEA Escova de Dentes
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Vyankatesh Ashtekar
Indian Institute of Technology Kanpur
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A device that
combines the functionality of toothpaste and toothbrush
Mission Statement
is light weight, compact, easy to use
is independent and travel ready
A toothbrush with paste filled within. Utility enhanced with features such
Product description
as tongue cleaner, dental floss etc.
Project goals Reduce preparation time, number of components, toothpaste wastage
Who can brush teeth on their own!
Primary market
And those who are learning to do it!
Secondary Market Travelers
Size same as old toothbrush or slightly larger
Expected characteristics Easy to operate and refill
Affordable , Good bristles and grip
Stakeholders Manufacturers, users, retailers
Avenues for creative design Add more features to improve utility
Amount of paste stored
Project scope/Limitations Number of feature incorporated
Cost
C. Function Structure
For toothpaste to reach bristles from toothpaste dispenser, different activities are to be carried out and their
relation is given by function structure. Fig. 1 shows function structure of the product. In function structure, thick
line shows material flow and normal line indicates energy flow while information flow is shown by dotted line.
D. Quality Function Deployment
The QFD method is used to find important engineering parameters in the design of toothbrush. Standard QFD
method is applied with 10 WHATs and 10 HOWs parameters. AURELLE TOOB and UltiBrush [3] are used as
references. QFD shows following parameters are more important in design.
1. Moderate length of toothbrush
2. High bristle quality
3. Less force to operate and refill
4. Easy assembly
5. Low cost
Fig. 1. Function structure of the toothbrush
Fig. 2. Toothbrush head with orifice Fig. 3. Toothbrush head with manual valve
2) TRIZ analysis
Using TRIZ [8] consists of three steps- identifying the problem, looking up the table of contradictions and trying
out the suggested inventive principles. The objective here is to improve adaptability of the mechanism and
volume of the moving object i.e. paste in this case. While doing so, the conflicting parameters are- area of the
moving object, amount of substance,manufacturability and energy spent by moving object.With selected
conflicting design parameters, the contradiction table suggests following inventive principles:
a) Nesting (07): It says that two parts may be nested. It hints that there should be some kind of function
sharing. In this case, the toothpaste pouch is placed inside the actuating mechanism i.e. the helix, which in turn
is placed inside the outer cylindrical body of the toothbrush.
b) Inversion (13): The mobile parts are made immobile and vice versa. Toothpaste pushing mechanism
inversions were tried out
c) Flexible film or thin membrane (30): It states that an object may be isolated from its environment with
a thin film or fine membranes. This inspired the idea of putting paste in a separate removable pouch.
B. Concept Evaluation
Decision matrix is used to find out the best generated concept for performing the required functions mentioned
in the morphology chart. After applying the decision matrix method, it is found that orifice would be the most
suitable mechanism for transferring the toothpaste on bristles. Similarly, transfer of toothpaste from dispenser to
head of toothbrush is more favorably done by using helix grooves technique. For connecting the toothbrush head
with the dispenser body threads are preferred.
IV. DESIGN AND ANALYSIS
A. Structural and Mechanism design
Fig. 5 shows assembly view of the designed toothbrush.
1. Bristles
2. Toothbrush head
3. Outer cylinder (body)
4. Inner helix
5. Collar
6.Dispenser Pouch
B. Working of Toothbrush
Outer cylinder (refer Fig. 5) is used to hold all parts of the toothbrush and other attachments. The outer cylinder
has the two axial straight grooves which enable the axial motion of collar. Inner cylinder, placed inside the outer
cylinder, has helical grooves. With rotation of inner cylinder, collar inside it moves axially by screw action and
pushes the paste in forward direction. The toothbrush head has bristles on one side and the tongue cleaner on the
back side. It also has aductthrough which toothpaste flows up to the bristles. Toothpaste comes out of an orifice
at the end of the ductin toothbrush head. It also resists from water flowing back in the toothpaste dispenser. The
toothpaste dispenser pouch is placed inside the inner cylinder.
Where, V is the averagge velocity off the toothpasste, L is length h of pipe, D is i diameter off pipe, g is acceleration
due to grravity, f is thee friction coeefficient. k1, k2 and k3 are minor loss cooefficient. Preessure requireed to push
toothpastte out of orificce,
1450 2
Force to be applied at plunger produuct of pressuree and area of plunger. p It com mes out as0.22915 N. Now torque
t (T)
required rotating helixx is can be calcculated. Forcee (F) applied to o rotate inner helix is givenn by,
tan n
∙ ∙ 3
2 1 ∙ taan
Where dm is mean diaameter of inneer helix, μ is coefficient off friction betw ween inner heelix and dispeenser, α is
helix anggle of inner cylinder. Theerefore, force required forr the operatioon the toothbrrush comes out o to be,
F=0.95344 N. This valuue is fairly small to operate by thumb.
V. OTHER ASPECTS
A. Failuure mode and effect
e analysiss
To deterrmine mode of o failure of every e componnent in produ uct and its efffect on overaall functionality of the
product FMEA
F analyssis is carried out. o From FM MEA analysis table it is fouund out that thhe collar (Rissk Priority
Number (RPN) =200) is the most critical c compoonent in the design,
d its reliability has to be improved. Detailed
FMEA iss given in Tabble A in Appenndix.
B. Valuee Analysis
Toothbruush head and outer body is i manufacturred by injectiion molding. Bristles are stapled onto the head.
Helixes are
a made by spiral
s formingg. Dispenser pouch is manu ufactured by blow molding. Cost of polyp propylene
is assumeed to be INR 63.48/kg.
6 Thee overall cost of o the productt comes out bee INR 40 apprroximately. This cost is
calculated purely for value
v analysis of the producct and does no ot consist of anny other overhheads and marrgins. Fig.
6 shows value analysiis of our toothhbrush. Parts of o the toothbrrush are in rigght most colum mn while fun
nctions are
listed onn top row. In a cell, top right number indicates i wortth and bottom m left numberr indicates co ost of part
relative to
t function. Frrom value anaalysis, we seee out that tooth hpaste motionn is worth a loot function bu ut actually
bristles cost
c a lot. Therre are no suchh parts whose elimination will w reduce the cost further.
V SUMMARY
VI. Y
Design of
o the toothbruush is accompllished using well-known
w prroduct design principles whhich enhance designer’s
d
intuition.. The toothbruush designed contains toothhpaste within it and once reefilled, it can be used for at
a least 15
days wheen used daily once. The forrce required too operate tootthbrush is smaall enough to be operated by b thumb.
The desiggn is such thaat complete teeeth cleaning process can be
b accomplishhed by single hand, which is a great
benefit foor the disadvaantaged.
TABLE III VALLUE ANALYSIS OFF TOOTHBRUSH
R
REFERENCE
ES
[1] Yu, Hai-Yang;
H Qian, Lin-Mao;
L Zheng, Jing (2013),Denttal Biotribology, Springer. pp. 18––19. ISBN 978-1--4614-4550-0.
[2] "Whoo invented the tooothbrush and wheen was it? (Everydday Mysteries: Fu un Science Facts from the Libraryy of Congress)". lo
oc.gov.
[3] UltiBrushhttp://ultibruush.com/
[4] Shao--Kai Pei, “Brush having
h storage baag”, US8851782 B2, issued Oct 7, 2014
[5] Kyu HoH Kwak,”Valve means for toothbbrush containing toothpaste dispen nser therein”, US44826341 A, issueed May 2, 1989
[6] Narenndra Sudhakar Shhinde,”A device with brush for controlled dispen nsing of liquid/paste from replacceable tube cartriidge” Indian
Patennt 254023, issued Sept 14, 2012
[7] Martiin; Todd A., “Tooothpaste dispensinng toothbrush”, USU 5908257, issued Jun 1, 1999
[8] Hua, Z.; Yang, J.; Cooulibaly, S.; Zhanng, B. (2006). "Inntegration TRIZ with problem-soolving tools: a litterature review frrom 1995 to
2006"". International Joournal of Businesss Innovation andd Research, 1 (1-2
2): 111–128. Retrrieved 2 October 22010
[9] B.D. Johns,”Paste-N-B
J Brush”, US73677737 B2, issued Maay 6, 2008.
[10] C.D. Gordon,”Toothbr
G rush assembly wiith toothpaste disppenser”,US 6729789 B2, issued Apr
A 22, 2003
[11] D.J Rosenberg,”Comb
R bination toothbruush and toothpastee dispenser” US 6206600
6 B1,issueed Nov 18, 1999
[12] Y. F.. Zhu, "A Designn Principle of Tooothbrush Handlee Based on Ergon nomic Theory", Applied
A Mechaniics and Materialss, Vols. 121-
126, pp.
p 622-626, 20122
[13] AshfaaqAkram,Thean Hock H Tang, Boonn Suen Ang, Robbina Shaheen, Ab bdel Hamid Zaki,, “Perception of a New Design off Toothbrush
by Itss Users”, IOSR Joournal of Dental and
a Medical Scieences (IOSR-JDM MS) e-ISSN: 22799-0853, p-ISSN: 2279-0861.Volum me 14, Issue
5 Verr. I (May. 2015), PP
P 58-61
[14] Bealss D , Ngo T , Feng Y , Cook D , Grau
G DG , Weber DA,”Developmeent and laboratoryy evaluation of a new toothbrush with w a novel
brushh head design”,Am merican Journal ofo Dentistry [20000, 13(Spec No):5A A-14A]
APPENDIX
TABLE A: FMEA OF TOOTHBRUSH
Occurrence
Detection
Severity
Potential Potential cause of Potential effect(s) of Recommended
SI.No Part RPN
failure mode failure failure action