DOE Applications. Oct 16th 2002 ASQ Section 702: San Gabriel Valley by Dr. Raj Palanna. Objective of Talk. Give a “flavor” for actual applications of DOE in industry Provide an insight into how complex theoretical concepts are applied in real-world situations
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DOE Applications Oct 16th 2002 ASQ Section 702: San Gabriel Valley by Dr. Raj Palanna
Objective of Talk • Give a “flavor” for actual applications of DOE in industry • Provide an insight into how complex theoretical concepts are applied in real-world situations • Build on the ASQ 702 September presentation DOE - Basic Concepts by Dr. Kurt Palmer
Agenda • Deep Dive - 2 Examples • Quick High Level Overview - Few More Applications • Q&A * These examples are taken from applications at different companies. Some of the data and facts have been “coded” to protect proprietary information.
1. ECS Pack Switch Failure Investigation • Starting February 2002 (until April 2002) a total of 21 switches have been rejected at XXX Aircraft Company’s aircraft test line, for failure to “open” at max. 200 deg. F. • Shipments of multi million dollar aircraft are at risk
Key Planning Aspects • Immediate containment actions taken • Teams working at 3 tiers of supply chain • Evaluate the “usual suspects”* • Testing setup and process • Manufacturing process • Application at system level, etc • Different schools of quality uses slightly different methods for this exercise * This presentation will concentrate only on the DOE aspect of the problem
DOE Problem Statement • Parts that failed at customer passed at supplier test process. Test method is a suspect. A DOE was set up to understand the sensitivity of switches to the test parameters • 6 Parts were chosen for DOE - 3 New, 3 Rejected
DOE Pre-planing • A complex DOE THOUGHT MAP was developed • Factor Selection • Response Selection • Measurement Repeatability Studies • Noise Impact • Confounding • Randomization • Resource Logistics • Management Approvals • Observation/ Copious Notes • etc
DOE Orthogonal Matrix Building Exercise • You Have Been Tasked to Optimize Gas Mileage on Your Car • Team Needs to Test 4 Factors • Has Resources for 8 Runs • Res. IV Confounded Design in Acceptable (Don’t worry if you don’t understand this bullet!!) • What is the DOE Matrix?
DOE Matrix 24-1ResIV
DOE Analysis:“Rejected” Switches Average Trigger Temperature Type of TESTING OIL (C) influences test results and Type of MOUNTING (D) influences test results
DOE Analysis:“New” Switches Average Trigger Temperature No Impact of Factors A, B, C and D on “New” Switches
Spread of Results Under Different Testing Conditions Switches from New Batch Higher Spread Has been Observed in “Rejected Switches” Switches from Customer ‘Rejected” Batch
Conclusions • A particular batch of switches were found to be in under-fill condition and switches became “sensitive” to testing parameters/ operating conditions and lost its robustness to environment • Manufacturing process was fixed • Test was augmented to prevent this situation from happening again
2. Aircraft Motor Performance Optimization • Problem statement: shop failures at test. Brake was releasing under the “brake release voltage specification” • Evaluate the “usual suspects” • Testing setup and process • Manufacturing process • Application at system level, etc • Developed a DOE thought map
DOE Matrix .. Motor 25-1ResIV
Use : • Run-In • High Armature TIR • Flat Disk
Test for Statistical Significance Results Are Statistically Significant
Randomness Test There is No Unusual Observations
Conclusions - Motor DOE • Experiment showed statistical significance. • Settings for Static Brake • Brake Cycling….Introduce Brake Cycling in MOT- Chuck • High Armature TIR.???? Do we ask for “bad parts”? • Flat Disk….Within 1/10th..Need Process Control • With Low Disk Flatness Use 3 mm(Low) EndPlay. (With Flat Disk Set Low EndPlay). Change MOT - Chuck. • This will improve Static Brake Problems.
3. Nozzle Air Flow Optimization DOE • Problem statement: air cycle machine nozzle hole-to-hole variation need to be minimized to improve system performance • Process: multi spindle drilling • DOE response: diameter sigma between different holes in a single nozzle • Factors: machining factors • Reamer speed, Reamer feed, Reamer diameter, Stock (after drilling)
4. Vapor Cycle Pack Bearing Failure Investigation • Problem statement: bearing failures of VCS pack on aircraft • Type of DOE: design robustness evaluation • Response: measure of fatigue on the bearing after specified run time • DOE factors: product design variables
5. DOE for Car Door Panel Delimitation Problem • Problem statement: delaminating of vinyl from the foam substrate of an car door interior • Process: door panel molding process • Response: lamination evaluation on a likert scale + measure of area of delaminating • DOE factors: molding machine factor • Overall temp, Heat upper, Heat lower, Oven temp, Backing type, Density, Vacuum pressure, Vacuum delay
6. Actuator Pin Alignment DOE • Problem statement: aircraft door actuator connector pin alignment out of specification • Type of DOE: combination assembly process evaluation plus design features evaluation • DOE response: distance from nominal in circular domain • DOE factors: assembly technique variables plus part features • Twist, Length, Sleeve
Practice Idea:Gas Mileage Optimization DOE • Problem statement: pick a response variable to optimize on the car (gas mileage…) • Choose factors that might influence this output response variable • Setup the DOE, run the DOE, analyze DOE • Other ideas: • Optimize volume of popcorn produced • Etc……. Any suggestions from audience? DOE Is Not the Easiest Application Tool Around Town…. But If You Master DOE, You Will Be a Champion QE!! Practice, Practice, Practice
Appendix • Reference Books • Douglas C. Montgomery: Design and Analysis of Experiments • Ronald D. Moen Et Al.: Improving Quality Through Planned Experimentation • Madhav S. Phadke: Quality Engineering Using Robust Design • Software • Minitab • JMP • Etc