1. BUTTERFLY PLATE THREADED
INSERT IMPROVEMENT EFFORT
A SUBMISSION FOR DESIGN OF EXPERIMENT
Prepared By:
NISARG SHAH
GURKIRAN KAUR
MILAN PATEL

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1.0 Objective
The objective of this experiment is to determine which factors affect the loosening or
movement of the threaded inserts in the butterfly plates. Once these factors are identified,
an optimal combination of factors and level settings will be used to minimize the insert
movement. Additional experimentation beyond this first experiment may be required.
2.0 Procedure
In this experiment half factorial method is used. Minitab is used in order to simulate all the
results.
We have taken 5 factors in consideration which are as follows:
 Tooling
 Cati-coat
 Minor diameter
 Pitch diameter
 Insert type
In this experiment, we are using the generator: I=ABCD.
Lastly we have used Minitab software for analysing the significance of the main effects
and interaction effects.
2.1 Pre-Experimental Planning
2.1.1 Recognition and Statements of the Problems
Threaded inserts are helically formed coils of diamond shaped steel wire that re threaded
into a drilled and pre tapped hole. They provide a controlled level of friction to the installed
screw or setscrew, which keeps the screw or setscrew in place even in a high vibration
environment.
Threaded inserts in particular pneumatic valve butterfly plates have a tendency to come
loose when the setscrew is being installed. When this happens, the valve usually must
be disassembled and the butterfly plate removed in order to rework the butterfly plate to
reinstall a new insert and setscrew.
There are different versions of this butterfly plate with different kinds of inserts and plate
base materials. It is unknown which combinations of materials, inserts and other factors
are causing the problem.

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2.1.2 Choice of Factors and Level
Table 1: Design Factors Table
Factors Level
Tool 2(New or Existing)
Cati-coat 2(No or Yes)
Minor Diameter 2(.171”dia(tight) or.178”dia(loose))
Pitch Diameter 2(H2 or H5)
Insert 2( Helicoil and 10 digit)
 Tool
A tool currently exists to install the inserts, this will be one factor level. A new tool was
purchased as a second factor level. One of the insert manufacturers believes the tooling
used can make a difference.
 Cati-coat
First-hand experience leads the technicians involved in the installation of inserts to
believe that cati-coat corrosion preventative applied to the threaded hole prior to insert
assembly helps to keep the insert in place.
 Minor Diameter and Pitch Diameter
There is an allowable tolerance on the threaded –hole size that insert is installed in. High
and low settings were chosen for these two features that determine threaded hole size. It
is believed these two features have an effect on the amount of friction between the
threaded hole and the insert.
 Insert
The types of inserts are known as helicoil and 10 digit.
2.1.3 Selection of response variable
In this experiment the value of responsible variables were chosen randomly and we did
not consider any specific method of generating this random variables.

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2.2 Choice of Experiment
Half factorial design (2k-p)
Number of replicates =1
Experiments =16
Number of blocks=0
Number of factors=5
2.3 Performing the Experiment
The experimental design is called for 32 runs.it was unreasonable to obtain 32 butterfly
plates to use for this experiment. To resolve this problem, two rectangular test beds were
manufactured of the same material as the two butterfly plates. The thickness of the beds
were the same as in the butterfly plate application. The holes in the plate were drilled and
tapped to include the factor settings of the minor diameter and pitch diameter factors.
2.3.1 Experimental setup and conduct of runs
In this experiment, we are using 2k-p fractional factorial design. The value of k is 5 and p
is 1, hence we get a total of 16 runs.
2.3.2 Experimental Procedures
The response variable is the movement of the insert. The movement will be measured by
angular displacement of the insert from its installed position. This angular measurement
was done usually by two people. The figure below gives an example of insert movement.
Any deviations more than 10 degrees was made compatible by reviewing disputed
measurements.

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Table 2: Response Table
Std
Order
Run
Order
Tooling
Cati-
Coat
Minor
Dia
Pitch
Dia
Insert
Type
Response
1 5 Old No 0.171 H2 helicoil 8
2 10 New No 0.171 H2 10 digit 9
3 7 Old Yes 0.171 H2 10 digit 34
4 9 New Yes 0.171 H2 helicoil 52
5 14 Old No 0.178 H2 10 digit 16
6 1 New No 0.178 H2 helicoil 22
7 3 Old Yes 0.178 H2 helicoil 45
8 13 New Yes 0.178 H2 10 digit 60
9 4 Old No 0.171 H5 10 digit 6
10 11 New No 0.171 H5 helicoil 10
11 2 Old Yes 0.171 H5 helicoil 30
12 12 New Yes 0.171 H5 10 digit 50
13 8 Old No 0.178 H5 helicoil 15
14 16 New No 0.178 H5 10 digit 21
15 15 Old Yes 0.178 H5 10 digit 44
16 6 New Yes 0.178 H5 helicoil 63
2.4 Statistical Analysis of data
First of all, all the response variables are analysed with Yate’s Algorithm.
The aliasing of the main factors and interactions are shown below in the table and the
generator is mentioned above.
From the Yate’s Algorithm, we obtain the contrast (Column name: “4”), from which we
calculated the Estimated Effect and Sum of Square

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Table 3 Estimation of Effect and Sum of Squares (Yate’s Algorithm)
From the above analysis and from the values of sum of squares we can say that the value
of A, B, C and AB appears to be large. Further, the other main effects and interaction
effects does not seems large hence adding them to error. From the above assumptions
the following ANOVA table is created.
The model sum of squares is SSModel = SSA + SSB + SSC + SSAB = 5747.25, and this
accounts for over 99 percent of the total variability.
Treamtment
Combination
Standard
Order
Run
No.
Respons
e
1 2 3 4 Effect
Estimation
of Effect
Sum of
Sqaure
abcde 1 14 8 17 103 246 485 -- -- --
a 2 7 9 86 143 239 89 A + BDCE 11.125 495.0625
b 3 6 34 38 96 40 271 B + ACDE 33.875 4590.063
cde 4 4 52 105 143 49 55 AB + CDE 6.875 189.0625
c 5 5 16 16 19 136 87 C + ABDE 10.875 473.0625
bde 6 10 22 80 21 135 3 AC + BDE 0.375 0.5625
ade 7 12 45 36 24 26 5 BC + ADE 0.625 1.5625
abc 8 3 60 107 25 29 -11 DE + ABC -1.375 7.5625
d 9 15 6 1 69 40 -7 D + ABCE -0.875 3.0625
bce 10 8 10 18 67 47 9 AD + BCE 1.125 5.0625
ace 11 16 30 6 64 2 -1 BD + ACE -0.125 0.0625
abd 12 13 50 15 71 1 3 CE + ABD 0.375 0.5625
abe 13 2 15 4 17 -2 7 CD + ABE 0.875 3.0625
acd 14 1 21 20 9 7 -1 BE + ACD -0.125 0.0625
bcd 15 11 44 6 16 -8 9 AE + BCD 1.125 5.0625
e 16 9 63 19 13 -3 5 E + ABCD 0.625 1.5625

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Normal Probability Plot:
From the normal probability plot of the effects, also we can see that effects A, B, C and
AB are significantly high. Hence adding other main effects and interaction effects to
error.
Table 3 Analysis Of Variance
Source of
variation
Sum of squares Degree of
freedom
Mean square F0
A 495.0625 1 495.0625 193.20
B 4590.0625 1 4590.0625 1791.24
C 473.0625 1 473.0625 184.61
AB 189.0625 1 189.0625 73.78
Error 28.1875 11 2.5625
TOTAL 5775.4375 15

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As we can see here that 3 out of 5 main effects are significantly high at α = 0.05 and even
at α = 0.01 level, and one Two factor interaction is also significant at the same level.
From the Fishers table we obtain the value of F0.05,1,11= 4.84 and F0.01,1,11= 9.65
Hence from ANOVA Table, we can conclude that the effects of A,B,C and AB are
significantly large. This supports our earlier assumption that effect A, B, C and interaction
effect AB are significant and proves our assumption.
The main factors A, B and C and the interaction AB have large positive effects. From the
interaction graph it is clear that when A is high and B is high, the yield is large.

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3.0 Conclusion
 Main Effects:
The 3 main effects out of 5, Tooling, Cati-Coat and Minor dia are significantly
high, as F0 < F0.05,1,11= 4.84, also F0 < F0.01,1,11= 9.65, hence we can say that
main effects Tooling, Cati-Coat and Minor dia are significant at even 1% level of
significance.
In order to minimize loosening or movement of threaded parts in butterfly plates,
Tooling should be used old with no Cati-Coat and 0.171 Minor Dia.
The Response plot for main effects is shown in the plot below.

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 Interaction Effect:
Only the interaction between Tooling and Cati-Coat is significant, as F0 < F0.05,1,11=
4.84, also F0 < F0.01,1,11= 9.65, hence we can say that interaction between Tooling
and Cati-Coat is significant at 1% level of significance.
From the graph, we can say that, in order to minimize the loosening or movement
of threaded parts in butterfly plates, it should be used at low level of Tooling and
low level of Cati-Coat.
The plot showing interaction of Tooling and Cati-Coat is shown below.
Based on this experiment, the factor setting to settings to reduce the insert movement
are:
Old Tooling
No Cati-Coat
0.171” Minor Dia
Any of the pitch dia
Any of the insert