Process Control Chart using minitab

So, we have gathered 100 raw sample data from experiment and got this beautiful

From x-bar chart, we see that there are one point that is out of our upper control limit, which I assume its acceptable in real world manufacturing, and have no points outside of our control limit on R chart which is good. This indicates that our process was in control. However!!!!, Cp and Cpk is poor!!! meaning that our variation within and between individual samples were huge. Our process, although it was stable, is not capable of making products within its specs. If this was real manufacturing company situation, we should have went out of business due to poor reputation from this...... What we did next was trying to improve these numbers by come up with new strategy. Okay.... we decided to implement some magical method to improve our manufacturing process. lets see what it gives us after doing the same thing

 okay........... X bar chart looks better.... our Cp increased little bit... out Cpk decreased........... this is because our mean has shifted due to this change in process. Anyways... not too much improvement... we just wasted money and time.... So! now, we tried DOE, design of experiment, to see what is actually causing this variation. We had 4 factors in our DOE. Operator, hand, position, and cup level.

hmmmm............ Looks like that there is significant drop in process mean when cup level is different with operator 2. I mean overall, operator 2 have relatively larger variation than operator 1. From this data, I would say that most critical factor that influences our variation is cup level. So lets go fix cup level to optimal level!!!!! 

ENERGENCY FUEL DUMP SYSTEM

RELIABILITY ANALYSYS

PREPARED BY

Young Kim

Javier Molina

E419 Spring 2013

Professor Joseph Berk

1.0  SCOPE:

The following report is a Reliability Analysis detailing mathematical models and reliability predictions for the Emergency Fuel Dump System, abbreviated as EFDS, presented in IE419. The system reliability is calculated and determined to be

2.0  REFERENCE DOCUMENTS:

A. MIL-HDBK-217F

B. RIAC  AUTOMATED DATABOOK(NPRD-2011)

C. LECTURE SLIDES

3.0  OVERVIEW:

The design of EFDS is broken into two major sections. These sections are Relay-Actuated Barrier, which is blocking the piston from penetrating fuel tank in case of malfunctioning of system when idle. Another main section is Piston with Pressure Cartridge, responsible for penetrating fuel tank when powered by power supply. These two main sections operate independent to each other, but, both of them have to work simultaneously in order for the system to successfully work.

4.0  ASSUMPTIONS:

The following assumptions were made for the calculation of reliability:

a. Electrical parts of system were modeled after MIL-HDBK-217F

b. The aircraft is a fixed wing military aircraft

c. Calculated Time (Hours) = 3 hours

d. Temperature = 35°C

e. Relay Cycle Time ≤  1 Hour

f. Contact form of the Relay = SPST

g. Parts for the fuel tank do not affect the reliability of the system

h. Only two bolts and O-ring are necessary for the pressurized cartridge system to work properly

i. Aircraft is operating in environment that is ¼ hazard than that of operating in AA environment

5.0  Rationale for failure rate prediction:

For the parts that are not list on either NPRD-2011 or MIL-HDBK-217F, rationales made were that it is going  to have same failure rate or twice of that of the parts that are essentially performing similar jobs. 

Such Parts includes: Gland, Tank, Barrier, and Piston.

6.0  Block diagram

Failure Mode and Effects Analysis for Hydraulic Thermal Relief Valve

The following report was created for educational purpose only and based on the engineering drawing only.

No real sight inspection was performed :)

FAILURE MODE

AND EFFECTS ANALYSIS

PREPARED BY

Young Kim

Javier Molina

E419 Spring 2013

Professor Joseph Berk

REVISION PAGE:

REVISION        DATE                           DESCRIPTION

      N/C                        05-13-2013                  Initial Release

1.0  SCOPE:

The following report is a Failure Modes and Effects Analysis detailing mathematical models and predicted possible failure modes and its effects of the Hydraulic Thermal Relief Valve, part number 2623-13, designed by PneuDraulics, Inc. With precisely predicted failure rates for each part in assembly, meantime between failures of the whole system is calculated to be 563799 hours with total failure rate of 1.774 per every million hours.

2.0  REFERENCE DOCUMENTS:

A. MIL-HDBK-217F
B. RIAC  AUTOMATED DATABOOK(NPRD-2011)
C. LECTURE SLIDES
D. NPRD-95

3.0  REFERENCE SOFTWARE:

For the prediction of the failure rates, MTBF Calculator software developed by ALD is used

4.0  ITEM OVERVIEW:

The Hydraulic Thermal Relief Valve is designed to release the pressure if the systems pressure gets too extreme. This is done by poppet assembly, containing ball attached at the end and spring guide, which provides the spring to be compressed in designed way, pushing down spring due to over pressure to make opening space between the ball attached on poppet assembly and the seat.

5.0  ASSUMPTIONS:

a. Custom made mechanical parts were modeled after NPRD-95
b. The part is operating under high pressurized environment
c. Calculated Time (Hours) = 3 hours
d. Operating Temperature = -65°F to +165°F

6.0  FAILURE MODES AND EFFECTS ANALYSIS:

The FMEA has been developed to be used for the following purposes:

a. To identify all failure modes and ensure that corrective action has been taken
b. To identify effects of failure modes on the system under different level of assembly
c. Tool as a ranking technique to be used to concentrating on more severe possible failure modes

7.0  FMEA PROCEDURE

The Failure Modes and Effects Analysis is presented in tabular form in EXCEL. The worksheet has various columns detailing several of different facts related to FMEA. A description of each column is as follows:

Indentured Drawing Number – This FMEA column identifies the component’s drawing number according to its engineering drawing. For Hydraulic Thermal Relief system, drawing 2623-13 is used for this information.

Part Name - This FMEA column identifies component’s nomenclatures based on drawing 2623-13

Part Number - This FMEA column identifies component’s part or identification number based on drawing 2623-13.

Quantity - This FMEA column identifies quantity of each part needed for single assembly. The information is based on the drawing 2623-13.

Failure Mode - This FMEA column identifies all of the possible failure modes that a single component can have under its assumed operating condition.

Failure mode Rate(%) - This FMEA column identifies weighted percentage of each failure mode under one single component. For example, for the part shim, there are two possible failure modes identified. It can fracture but remain in intact or it fractures and releases. The failure mode rate for those two failure modes are 30% and 70%.

Failure Mode Cause - This FMEA column identifies the possible causes of each failure modes stated for each part.

Failure Rate(per million hours) - This FMEA column identifies the failure rate, per million hours. This information is predicted using NPRD-95 for custom made mechanical parts and NPRD-2011 for other mechanical parts.

Failure Rate Source - This FMEA column identifies sources used to predict the failure rate. Two sources used in this typical report are NPRD-95 and NPRD-2011

Component Level - This FMEA column identifies possible problem each failure mode may cause in component level of assembly.

Next Assembly Level - This FMEA column identifies possible problem each failure mode may cause in a next assembly level.

Visible Or Hidden - This FMEA column identifies if the failure modes are visible or not by inspection.

Criticality - This FMEA column identifies its severity and it is divided into 4 sub criteria.
                        I. Catastrophic - May cause death or weapon system loss.

II. Critical – May cause severe injury or damage and may result in mission loss.

III. Marginal – May cause minor injury or damage and may result in delay in mission   degradation
IV. Minor – It is not serious enough to cause the damage or injury to the part or system.

Means of Detection - This FMEA column identifies how failure can be detected if it occurs.

Compensating Provisions - This FMEA column identifies what features prevent or mitigate failure occurrence.

8.0  Failure Rates and MTBF:

- Total Failure Rates for the system came out to be 1.773683*10^-6 hours.

- The MTBF for this particular system under the assumptions made is calculated by taking inverse if      total failure rates and comes out to be 563799 hours.

9.0  FMEA Table and Engineering Drawing:

The following embed FMEA Table in EXCEL and Engineering Drawing is provided below as an embedded files as reference to this report.

        FMEA                              Engineering Drawing
                      

(original report have these two files embedded inside of report, :( too bad this won't let me do it)


Acutual FMEA in tabular form is here (for some reason, lines are not showing :(   srry!)

PART IDENTIFICATION

FAILURE DATA

FAILRUE EFFECTS

COMMENTS

Indentured Drawing Number

Part Name

Part Number

Quantity

Failure Mode

Failure mode Rate(%)

Failure Mode Cause

Failure Rate Million per hour

Failure Rate Source

Component Level

Next Assembly Level

Visible Or Hidden

Criticality

Means of Detection

Compensating Provisions

1

VALVE,HYDRAULIC THERMAL RELIEF

2623-13

1

See below

1.773683

See below

1.1

HOUSING

16726

1

0.4

NPRD-95

Minor internal leakage

23.00%

Wear, installation damage, contaminant presence

0.092

Minor leakage to interior

None, other than requirement to repair at next maintenance opportunity

HIDDEN

IV

OPERATIONAL

Use correct surface finishes,and materials for  specification enviroments

Major internal leakage

2.00%

Wear, installation damage, contaminant presence

0.008

Major leakage to interior

loose of valve function

VISIBLE

II

VISUAL

Use correct surface finishes,and materials for  specification enviroments

Minor external leakage

29.00%

Wear, installation damage, contaminant presence

0.116

Minor leakage to exterior

None, other than requirement to repair at next maintenance opportunity

HIDDEN

IV

OPERATIONAL

Use correct surface finishes,and materials for  specification enviroments

Major external leakage

3.00%

Wear, installation damage, contaminant presence

0.012

Major leakage to exterior

Loose of Hydraulic fluid

VISIBLE

I

VISUAL

Use correct surface finishes,and materials for  specification enviroments

fractures

16.00%

Excess shock or other load

0.064

Housing Fractured

Loose of Hydraulic fluid

VISIBLE

II

VISUAL

Use correct surface finishes,and materials for  specification enviroments

Deformed

16.00%

Excess shock or other load

0.064

Hoousing deformed

None, other than requirement to repair at next maintenance opportunity

VISIBLE

II

VISUAL

Use correct surface finishes,and materials for  specification enviroments

Striped threads

11.00%

installation damage,Assembly damage

0.044

damaged threads

Difficult assembly

VISIBLE

II

VISUAL

Use correct surface finishes,and materials for  specification enviroments

1.2

INLET NUT

16727

1

0.005523

NPRD-2011

fracture and release

40.00%

Excess shock or other load

0.0022092

loose of valve function

Loose of Hydraulic fluid

VISIBLE

I

VISUAL

Use of inlet nut designed for specification environments

Fracture and no  release

5.00%

Excess shock or other load

0.00027615

Inlet nut fractured

None, other than requirement to repair at next maintenance opportunity

VISIBLE

IV

VISUAL

Use of inlet nut designed for specification environments

Strip

10.00%

Poor assembly technique

0.0005523

Damaged threads

Difficult assembly

VISIBLE

III

VISUAL

Use of inlet nut designed for specification environments

Jam

15.00%

installation damage,Assembly damage,corrosion

0.00082845

Jammed inlet nut

damage threads of Housing, equirement to repair at next maintenance opportunity

HIDDEN

II

OPERATIONAL

Use of inlet nut designed for specification environments

Loosens

30.00%

Improper installation, vibration

0.0016569

Inlet nut loose

Loose of hydraulic fluid

HIDDEN

I

OPERATIONAL

Use of inlet nut designed for specification environments

1.3

SEAT

16728

1

0.18682

NPRD-95

Fracture

15.00%

Excess shock or other load

0.028023

Fractured seat

Loose of pressure and hydraulic fluid

VISIBLE

II

VISUAL

Use of appropriate design for  specification environments

bent

15.00%

Excess shock or other load

0.028023

Bented seat

None, other than requirement to repair at next maintenance opportunity

VISIBLE

II

VISUAL

Use of appropriate design for  specification environments

Deform

15.00%

Excess shock or other load

0.028023

deformed seat

Loose of pressure and hydraulic fluid

VISIBLE

II

VISUAL

Use of correct seals, surface finishes, and materials

Leakeage

55.00%

Wear, installation damage, contaminant presence

0.102751

Minor or major leakage to interior

loose of pressure ,possible spring corrosion,loose of valve function

VISIBLE

I

VISUAL

Use of correct seals, surface finishes, and materials

1.4

POPPET ASSY

16729

1

See below

0.46

1.4.1

SPRING GUIDE

16730

1

0.16

NPRD-95

Major internal leakage

1.50%

Wear, installation damage, contaminant presence

0.0024

Major leakage to interior

None, other than requirement to repair at next maintenance opportunity

VISIBLE

II

VISUAL

Use of correct seals, surface finishes, and materials

Minor internal leakage

23.50%

0.0376

Minor leakage to interior

loose of pressure ,possible spring damage ,loose of valve function

HIDDEN

III

OPERATIONAL

Use of correct seals, surface finishes, and materials

fracture  and jam

60.00%

Excess shock or other load

0.096

Spring guide jammed

loose of pressure ,possible spring damage,loose of valve function

VISIBLE

I

VISUAL

Use of correct seals, surface finishes, and materials

fracture  and  no jam

10.00%

Excess shock or other load

0.016

Spring guide Fractured

loose of valve function

VISIBLE

II

VISUAL

Use of correct seals, surface finishes, and materials

Wears such that exces clearance

5.00%

Vibration, excessive Frecuency

0.008

Excess wear and clearance; loose spring guide

Loose of valve function

VISIBLE

IV

VISUAL

Use of correct seals, surface finishes, and materials

1.4.2

BALL

MS19060-1004

1

0.3

NPRD-95

Fracture and release

10.00%

Excess shock or other load

0.03

Fractured Ball and loose of valve function

loose of pressure ,possible spring damage,loose of valve function

VISIBLE

III

VISUAL

Use of appropriate material for design loads and specification environments

Fracture and no release

53.00%

Excess shock or other load

0.159

Fractured Ball

loose of pressure and loose of valve function

VISIBLE

I

VISUAL

Use of appropriate material for design loads and specification environments

internal leakage

20.00%

Wear, installation damage, contaminant presence

0.06

minor leakege to interior

loose of pressure and loose of valve function

HIDDEN

II

OPERATIONAL

Use of appropriate material for design loads and specification environments

jam

17.00%

0.051

jammed ball

loose of pressure

VISIBLE

II

VISUAL

Use of appropriate material for design loads and specification environments

1.5

SHIM

16731

1

0.001

NPRD-95

Fracture but remains intact

30.00%

Excess shock or other load

0.0003

Fractured shim

no flow of hydraulic  fluid ,high pressure on the system

VISIBLE

II

VISUAL

Use of Shim designed for specification environments

Fractures and release

70.00%

Excess shock or other load

0.0007

Fractured shim  and  loose of valve function

None effect

VISIBLE

I

VISUAL

Use of Shim designed for specification environments

1.6

NAMEPLATE

16732-13

1

0.034

NPRD-95

Fracture

50.00%

Excess shock or other load

0.017

Fractured Nameplate

No effect

VISIBLE

I

VISUAL

Use of appropriate design for loads and specification environments

Falls off

50.00%

Vibration, excess shock or other load

0.017

missing nameplate

No identification

VISIBLE

I

OPERATIONAL

Use of appropriate design for loads and specification environments

1.7

ORIFICE

60296-200

1

0.2872

NPRD-95

closes

85.00%

corrosion,contaminant presence

0.24412

blocked orifice and loose of valve function

blocked flow and loose of valve function

HIDDEN

I

OPERATIONAL

Use of appropriate design for  specification environments

corrode

15.00%

contaminant presence,corrosive enviroment

0.04308

corroded orofice

possible blocked orifice

VISIBLE

IV

VISUAL

Use of appropriate design for specification environments

1.8

G T RING

7007MR952T

1

0.10414

NPRD-2011

Minor external leakage

75.00%

Wear, installation damage, contaminant presence

0.078105

Minor leakage to exterior

None, other than requirement to repair at next maintenance opportunity

HIDDEN

III

VISUAL

Use of appropriate seal for design loads and specification environments

Major external leakage

25.00%

Wear, installation damage, contaminant presence

0.026035

Major leakage to exterior

loose of valve function and loose of hydraulic fluid

VISIBLE

I

VISUAL

Use of appropriate seal for design loads and specification environments

1.9

SPRING

C0180-032-0620S

1

0.012

springs does not compress

38.00%

Misalignment ,corrosive enviroment,fatigue

0.00456

NPRD-95

Damaged spring

loose of valve function

VISIBLE

I

OPERTIONAL

Use of appropriate spring  for loads and specification environments

fracture

24.00%

Misalignment ,corrosive enviroment,high frecuency

0.00288

Fractured spring

loose of valve function

VISIBLE

II

VISUAL

Use of appropriate spring  for loads and specification environments

Yielding

19.00%

Wear,corrosive enviroment,high frecuency

0.00228

Damaged spring

loose of valve function

HIDDEN

IV

OPERATIONAL

Use of appropriate spring  for loads and specification environments

compress  at lower pressure

11.00%

Relaxation,creep

0.00132

Damaged spring

loose of valve function

HIDDEN

III

OPERATIONAL

Use of appropriate spring  for loads and specification environments

Fatigue

7.00%

Wear,corrosive enviroment,high frecuency

0.00084

Damaged spring

loose of valve function

VISIBLE

III

VISUAL

Use of appropriate spring  for loads and specification environments

Corrosion

1.00%

corrrosive enviroment

0.00012

Damaged spring

loose of valve function

VISIBLE

IV

VISUAL

Use of appropriate spring  for loads and specification environments