Quality Control for PH of Tea Final Presentation YU Jiayi, CUI Liwen, CHEN Rui, GUO Dingcheng, CAO Qing 1

Project Overview Suggestions

PH

value Control Define DOE Improve Analyze Measure Gage R&R Off-line Experiments 2

Project Overview Control

Define

Improve Measure Analyze 3

Define (1/3) • Study Problem – As the PH value of tea beverage is an important quality index, we would like to study the factors that would affect the PH value through off-line experiments . – We expect to obtain the the recommended values related influence factors to obtain the recommended PH value, thus production of tea beverage.

guiding the real of 4

Define (2/3) • • Response (

y

) – PH value of tea beverage • Green Tea: PH value of 6.2 recommended Factors (

x

) – Temperature – Time – Percentage of Tea – Container (stainless steel, glass, ceramic, etc.) 5

Define (3/3) • Methodology: Design of Experiment – Off-line experiments – Gage R&R study – GLM • Identify significant factors • Specify relationships between

x

and

y

6

Project Overview Control Define Improve Analyze

Measure

7

Measurement Instruments Electronic PH-meter Electronic Scale Temperature-control Pot Measuring Cup 8

Gage R&R (1/6) • Experiment setting – pH meter – 3 operators – 3 cups of tea – 3 replicates – Parameters • 3g tea • 200 mL water • 8 min 9

Gage R&R (2/6) • Experiment without SOP – Effect of

operator

is significant – Contributions of total Gage R&R:

nearly 100%

• Repeatability: 62.57% • Reproducibility: 37.43%

Source

Part Operator Part*operator Repeatability Total

DOF

2 2 4 18 26

SS MS

0.01982 0.009911

1.01682 0.508411

0.02482 0.006206

1.7272 0.095956

2.78867

F

1.5971

81.9284

0.0647

P 0.309

0.001

0.992

10

Gage R&R (3/6) • Experiment without SOP 11

Gage R&R (4/6) • Experiment with SOP – Effect of

part

and

interaction

are significant – Contributions of total Gage R&R:

35.21%

• Repeatability: 14.72% • Reproducibility: 20.49%

Source

Part Operator Part*operator Repeatability Total

DOF SS

2 0.005341

MS

0.00267

2 0.001252 0.000626

4 0.000704 0.000176

18 0.001133 0.000063

26 0.00843

F

15.1789

3.5579

2.7941

P 0.014

0.129

0.058

12

Gage R&R (5/6) • Experiment with SOP 13

Gage R&R (6/6) • The gage has acceptable repeatability and reproducibility – Different operations of operators have large influence in R&R – A

proper SOP

is required to improve the performance of operators 14

Project Overview Control Define Improve

Analyze

Measure 15

Design of Experiment (1/2) • • • • 3 4−1 fractional factorial design Response variable: pH value (using pH meter) Tea: 憩园甘露 Initial model: – 𝑦 = 𝜇 + 𝐴 + 𝐵 + 𝐶 + 𝐷 + 𝐴𝐵 + 𝐴𝐶 + 𝐵𝐶 + 𝜖 A B C D

Factor

Temperature (C) Time (min) Volume of water (ml) Material of cup 60 2 50 Glass

Level

80 5 100 Ceramic 98 8 200 Stainless steel 16

Design of Experiment (2/2) • • Sequence of experiment – Three cups of tea are tested in the same period. – The cups are made of different materials. – The total time of each cup is different.

– Measure their PH at their own time point. Control of factors – Temperature: air-conditioner, thermos – Volume of water: measuring glass – Weight of tea: electronic balance 17

Design of Experiment

0 min 2 min 4 min

不锈钢 陶瓷 玻璃

8 min 8-0=8 min 7 min 6 min 7-2=5 min 6-4=2 min

18

Experiment process (1/4) • Experiment notes – Cleaning acidometer & container everytime after reading PH value to get accurate data – Put acidometer into tea at least 1 min before reading to get stable PH value – To save time, we compress 3 experiments into one 8 min cycle, with same water temperature 19

Experiment process (2/4) • Preparation – Make sure the 3 experiments’ parameter combination (3g tea-leaf, same temperature) • 2min, A mL water, B1 container • • 5min, A mL water, B2 container 8min, A mL water, B3 container – Measuring required water & three 3g tea-leaf – Put tea-leaf into 3 container 20

Experiment process (3/4) • Experiment cycle Pour A mL water into B3 container Pour A mL water into B2 container • Pour A mL water into B1 container • • • Read PH value Wash acidometer Put acidometer • • • Read PH value Wash acidometer Wash B1 container • Wash acidometer into B2 container • Wash B3 container 0 min 1 min 2 min 3 min 4 min 5 min 6 min 7 min 8 min Measuring A mL water Measuring A mL water Put acidometer into B1 container • • • • 8 min 5 min 2 min Read PH value Wash acidometer Put acidometer into B1 container Wash B2 container 21

Experiment process (4/4) Measure 3g tea All experiment instruments Experime nt Snapshot s 3 cups per cycle Read PH value 22

Design of Experiment (1/9) • Result of the initial model – All main effects are significant – Three interactions are not significant

Source Temperature Time Volume Material Temperature*Time Temperature*Volume Time*Volume Residual Total DOF Seq SS Adj SS Adj MS

2 0.110289 0.110289 0.055144

2 0.298689 0.298689 0.149344

2 0.877222 0.877222 0.438611

2 0.097356 0.097356 0.048678

4 0.019822 0.019822 0.004956

4 0.018889 0.018889 0.004722

4 0.015422 0.015422 0.003856

6 0.031578 0.031578 0.005263

26 1.469267

F

10.48

28.38

83.34

9.25

0.94

0.9

0.73

P

0.011

0.001

<0.001

0.015

0.5

0.52

0.602

23

Design of Experiment (2/9) • Residual plot 24

Design of Experiment (3/9) • Mean of main effect 25

Design of Experiment (4/9) • Interaction 26

Design of Experiment (5/9) • Result of model without interaction – 𝑦 = 𝜇 + 𝐴 + 𝐵 + 𝐶 + 𝐷 + 𝜖

Source Temperature Time Volume Material Residual Total DOF Seq SS Adj SS Adj MS

2 0.11029 0.11029 0.05514

2 0.29869 0.29869 0.14934

2 0.87722 0.87722 0.43861

2 0.09736 0.09736 0.04868

18 0.08571 0.08571 0.00476

26 1.46927

F P

11.58

0.001

31.36 <0.001

92.11 <0.001

10.22

0.001

27

Design of Experiment (6/9) • Residual plot 28

Design of Experiment (7/9) • Mean of main effect 29

Design of Experiment (8/9) • Residual vs. sequence 30

Design of Experiment (9/9) • • Recommended parameter – Time: 2min – Volume of water: 200ml – Material of cup: Ceramic – Temperature: 98C – Estimated pH: 6.231

Limitation: no consideration on the effect of – Reusing tea – Type of tea 31

Project Overview

Control

Define

Improve

Measure Analyze 32

Improve & Control • Improvements line to obtain can be made to the production a recommended PH value – Temperature: 98 ℃ recommended – Time: 2 minutes – Tea/water ratio: recommended 3g tea/200 ml water – Container: change the original stainless steel container to the porcelain container 33

Thanks 2014/06/13 34