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Application of Six Sigma Management Tools to Increase the Quality of a Catapult. Lei Chen: 2008210475 Kai Han: 2009210546 Ying Liu: 2009210559 Keming Zhu: 2009210563 Jiarui Fang: 2009210565. Agenda. Introduction Define Measure Analyze Improve Control Summary Future work.
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Application of Six Sigma Management Tools to Increase the Quality of a Catapult Lei Chen: 2008210475 Kai Han: 2009210546 Ying Liu: 2009210559 Keming Zhu: 2009210563 Jiarui Fang: 2009210565
Agenda • Introduction • Define • Measure • Analyze • Improve • Control • Summary • Future work
Introduction http://images.google.com.hk
Define • Defect • The inaccurate or imprecise shooting distance of the catapult. • Accuracy • Shift between the observed hitting point and the target hitting point. • Precise • Variation of shooting distances from the observed average. • Goal • Make the shooting distance of the catapult as accurate and precise as possible. • USL – LSL = 8.4 cm (2 diameters of the golf ball).
Establish measure system capability • 5 landing points and 3 operators • First try • Cast the ball to hit the ground directly. • Operators guess the landing point by watching then give the measurements. • Gage R&R: more than 30% • Improve • Blank papers with carbon papers
Establish baseline process capability Cp = 0.41
Improvement 1: tentative improvements Casting rod and strength
Process capability analysis Cp = 0.68
Improvement 2: design of experiment • The objective is to find optimal configuration for least variation • Response • Standard deviation • Shoot 5 times in each run in order to compute the standard deviation • Factors • Operator • 3 operators • Fixing Style • Hand • Ground • Trigger
Design of experiment • Result
Process capability analysis Cp = 1.31
Assess the relationship of key X and Y X: the distance between the trigger and the base of the catapult Y: the distance
Summary of increasing accuracy improvements Reject H0 • Standard deviation has been reduced from 6.76 to 2.12 • Do another experiment • Target Y: 200cm • By the regression model, X is 42.1cm • Fix the trigger and repeat casting 30 times • Results • Mean: 202.34 • Standard deviation: 2.36 • Range: 9.10 • Hypothesis testing
Summary of increasing accuracy improvements Cp = 1.16 Cpk=0.84
Control actions Heavy objects should be used to fix the base of the catapult. The trigger (a taper holder) should be fixed on the ground. Use the same shot ball.
Statistical process control (SPC) • Design the SPC experiment • Target Y: 200cm • By the regression model, X is 42.1cm • Fix the trigger and repeat casting 30 times • Notes • The regression model is rough • Truncation errors • Limitation of experiment conditions • Lack of real-time control policies • Focusing on the past product quality
Statistical process control (SPC) Analysis of SPC result
Statistical process control (SPC) • Discussion • Real-time control policy: adjust X to get a better Y • Find a confidence interval of X and adjust the value of X in the interval
Future Work Measure systems Material of the casting rod A more accurate regression model The trigger: work more automatically