Quality:
Production line- Tea
Infuse
Team
Ma Chi Fai
Shi Cai
Tao Li
Xiang Ji
Rui Lin
Everything starts with a question
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Q: How often do you change the tea leaf?
A: No idea, but it doesn’t matter
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so… Why don’t we try to answer the question ourselves?
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A improvement driven direction formed
Definite of the projects
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Target

Obtain infused tea with similar level of Tea Polyphenol

Balance between tea polyphenol and cost
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Demonstrate SIPOC analysis and
simulation
• Technician cannot provide the amount for
tea leave for the production line
Remark
SIPOC: Production line
Supplier
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 Heater session
Input
 Time of tea be infused
Process
Output
 Infuse for 10 minutes
 Concentrated of Tea
 Volume of water (100L )  Compress with high
 Water temp. (90 °C)
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pressure for rotation
simulation
 Type of tea…
Tea leave

2g of tea leave per
unit, 6 units
Water
 90 °C Water
 750 ml
 Dilution session
Polyphenol
 Amount of Tea leave
A
Customer
Infuse time
 4 minutes
Action
 Shake with
hands in
metallic
container
Methodology-Testing solution
Dissolve 15.037g
Na2HPO4. 7H20
with distilled water
(Solution A)
Dissolve 2.07g
KH2PO4 with
distilled water
(Solution B)
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Dissolve 15.037g
Na2HPO4. 7H20
with distilled water
(Solution A)
Dilute solutions A
to 250 ml
A
Dissolve 2.07g
KH2PO4 with
distilled water
(Solution B)
C
Mixture solution C
With PH7.5 value
Dilute solutions B
to 250 ml
Dissolve 0.1g FeSO4
with distilled water
(Solution D)
Mix solution D & E
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Dissolve 0.4g
C4O6H4KNa with
distilled water
(Solution E)
Mix 85% vol.%
Ha2HPO4 & 15%
vol.% KH2PO4
Mixture solution C
With PH7.5 value
Mix solution D & E
Dilute the mixture
to 100ml
Solution F
Dilute solutions B
to 250 ml
Dissolve 0.1g FeSO4
with distilled water
(Solution D)
Mix 85% vol.%
Ha2HPO4 & 15%
vol.% KH2PO4
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Dilute solutions A
to 250 ml
Dilute the mixture
to 100ml
Solution F
Dissolve 0.4g
C4O6H4KNa with
distilled water
(Solution E)
Mix 8g distilled
water with 5ml
solution F
Shake the mixture
Mix the mixture
with solution C
To 25ml
Mix 4g of sample
tea, 4ml distilled
water with 5ml
solution F
Shake the mixture
Mix the mixture
with solution C
To 25ml
Methodology-Testing solution
Dissolve 15.037g
Na2HPO4. 7H20
with distilled water
(Solution A)
Dissolve 2.07g
KH2PO4 with
distilled water
(Solution B)
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Dilute solutions A
to 250 ml
Mix 85% vol.%
Ha2HPO4 & 15%
vol.% KH2PO4
Mixture solution C
With PH7.5 value
Mix solution D & E
Dilute the mixture
to 100ml
Solution F
Dilute solutions B
to 250 ml
Control solutions
Mix 8g distilled
water with 5ml
solution F
Shake the mixture
Mix the mixture
with solution C
To 25ml
Dissolve 0.1g FeSO4
with distilled water
(Solution D)
Dissolve 0.4g
C4O6H4KNa with
distilled water
(Solution E)
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Sample solutions
A
Mix 4g of sample
tea, 4ml distilled
water with 5ml
solution F
Shake the mixture
Mix the mixture
with solution C
To 25ml
Mix 8g distilled
water with 5ml
solution F
Shake the mixture
Mix the mixture
with solution C
To 25ml
Mix 4g of sample
tea, 4ml distilled
water with 5ml
solution F
Shake the mixture
Mix the mixture
with solution C
To 25ml
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• Control solutions
• Sample solutions
Methodology Testing solution
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Role
Task
Role A
Weight and
pack tea
leave
Role B
Measure 750
ml distilled
water
Boil water
Role C
Prepare
Solution C
Prepare
Solution F
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Mix sample
solution
Setup Tea
leave ball
Infuse tea
Shake tea
Prepare
sample tea
Cool the
water

Operated by the same person at each role

Stir tea sample before used

Filter tea sample before used with filter paper

Cooled the sample tea to room temperature (about 26 °C) for 50
minutes。
Test the
sample
Record Data
Measurement
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Process Capability and Variability

Variance caused by Location: intuitively, liquid are uniform after stirring.

Variance caused by the property change after being infused.

Assuming that there exists a function:
𝑌 = 𝐹 𝑋 + 𝜀𝑡
for certain type of tea, where 𝜀𝑡 is standard normally distributed, F(.) is a discrete
function and very likely to be non-increasing

Suppose that we will infuse the tea for 𝑁 𝑠𝑡 time:
𝑈𝑆𝐿 − 𝐿𝑆𝐿
𝑍𝑠𝑡 =
2
2 𝜎𝑡2 + 𝑁
𝑖=1 𝐹 𝑖 − 𝐸
𝑁
𝐸=
𝐹[𝑖]
𝑖=1
Given in advance
Measurement - Design of Experiment
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Factors studied X

Times of tea be infused

A

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1, 2, 3, …
Type of tea

Non quantifiable

The difference of the first factor’s impact on
different type of tea
Y
 Response variable

concentration of Tea Polyphenols(茶多酚)
Measurement - Design of Experiment
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Measurement System Variation Analysis

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Variation due to Gage

A machine is used for measuring the concentration in the experiment.

Chemical reagent might change over time.
Variation due to Operators

Certain procedures are performed by the same operator through one block.
Measurement - Design of Experiment
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Other DOE Principles considerations

Randomization
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Replication vs. Repetition

Standard procedures

Aiming at insight
Blocking

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No subjective bias since we are using the machine to test the ingredient.
A fixed group of members for each different type of tea
Improvement
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PCA of the improved process

New function between X and Y:
𝑌 = 𝐹 𝑋 + 𝜀𝑡 ⇒ 𝑌 = 𝜀𝑖 + 𝜀𝑡
A
where 𝜀𝑖 is the error term of the new process.
𝑍𝑠𝑡 =
𝑈𝑆𝐿 − 𝐿𝑆𝐿
2 𝜎𝑡2 + 𝜎𝑖2
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
Hypothesis: the improved process can provide better with same material cost.

Tips:

𝜎𝑖2 might be influenced by how many blocks we are using, we are only comparing the
case that use the same average amount of tea.
Results of Jasmine tea
Jasmine Tea
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2
1.5
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M1-1
1
M1-2
M1-3
0.5
M1-4
M1-5
0
420
426
432
438
444
450
456
462
468
474
480
486
492
498
504
510
516
522
528
534
540
546
552
558
564
570
576
582
588
594
600
606
612
618
624
630
636
642
648
654
660
666
672
678
684
690
696
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Tea Polyphenols
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-0.5
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Wavelength
Infuse #
1
2
3
4
5
Tea Polyphenols
1.947
1.231
0.582
0.374
0.041
Tea Polyphenols decrease with
infuse #
Analysis – result
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Pu-erh tea
1.6
1.4
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Tea Polyphenols
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1.2
1
1
2
0.8
3
0.6
4
5
0.4
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6
0.2
400
406
412
418
424
430
436
442
448
454
460
466
472
478
484
490
496
502
508
514
520
526
532
538
544
550
556
562
568
574
580
586
592
598
604
610
616
622
628
634
640
646
652
658
664
670
676
682
688
694
700
0
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Wavelength
Infuse #
1
2
3
4
5
6
Tea Polyphenols
1.071
0.325
0.089
0.053
0.052
0.008
Different type of tea, different
shape of curves
Tea Polyphenols decrease with
infuse #
Decrease rate varies with kind
of tea leave
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When to change tea leave?
Suggestion 1: Observation

Change tea leave based on observation
Challenge
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Infuse #
1
2
3
4
5
6
• Label the 1st and 6th infuse tea
Pu-erh tea
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Infuse #
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1st
2nd
3rd
4th
5th
6th

Add transparent glass layer to the container for observation

From previous data, darkness is proportional to the
number of Tea Polyphenol
Tea Polyphenols
1.071
0.325
0.089
0.053
0.052
0.008
Concern: suggestion 1: Observation
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
Change tea leave based on observation
Challenge
• Label the 1st and 6th infuse tea
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A
Jasmine tea
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Let’s see the number of Tea Polyphenol of Jasmine tea
Analysis – result
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Tieh-Kuan-Yin Tea
1.6
A
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1.2
1
1
2
0.8
3
0.6
4
0.4
5
0.2
6
0
400
407
414
421
428
435
442
449
456
463
470
477
484
491
498
505
512
519
526
533
540
547
554
561
568
575
582
589
596
603
610
617
624
631
638
645
652
659
666
673
680
687
694
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Tea Polyphenols
1.4
Wavelength
Infuse #
1
2
3
4
5
6
Tea Polyphenols
1.339
0.924
0.576
0.294
0.250
0.149
Tea Polyphenols cannot be determined by
darkness (color)
Common quality problem
Why 3 types of tea?
Misleading if just investigate the Tieh-Kuan-Yin Tea and Pu-erh tea
Drawing a wrong solutions
Original Changing stragty
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Tieh-Kuan-Yin Tea
Pu-erh Tea
Jasmine Tea
Similar color
Color difference
Color difference
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Infuse #
1
2
3
4
5
6
Tea Polyphenols
1.339
0.924
0.576
0.294
0.250
0.149
Infuse #
1
2
3
4
5
6
Tea Polyphenols
1.071
0.325
0.089
0.053
0.052
0.008
Original method cannot provide uniform tea polyphenols, we need to
Infuse #
1
2
3
4
5
change
Tea Polyphenols
1.947
1.231
0.582
0.374
0.041
Proposed idea
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Infus Ball1 Ball2 Ball3 Ball4 Ball5 Ball6 Ball7 Ball8 Ball9 Ball1
e
0
1
1
2
2
1
3
3
2
1
4
4
3
2
1
5
5
4
3
2
1
6
6
5
4
3
2
1
6
5
4
3
2
1
6
5
4
3
2
1
6
5
4
3
2
1
6
5
4
3
2
7
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8
9
10
Change:
Throw in next infuse
Change:
Add in next infuse
Record
1
Number inside
Refer to Infuse # to that box
Analysis – result
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3.0000
2.5000
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2.5000
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2.0000
Tea Polyphenols
A
Tea Polyphenols
2.0000
1.5000
1.5000
1.0000
1.0000
0.5000
0.5000
C
0.0000
1
0.0000
1
2
3
4
5
Pu-erh tea
Jasmine Tea
Pu-erh tea
Tieh-Kuan-Yin Tea
3
4
Infuse #
6
Infuse #
2
Jasmine Tea
Tieh-Kuan-Yin Tea
Analysis - PCA
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Process Capability Analysis
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U-L
𝝈
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3
4
3
𝒛𝒔𝒕
4
3
4
𝝈
U-L
𝒛𝒔𝒕
Pu-erh tea
0.4185 0.4099 0.9820 1.0180 1.1731 1.2418
0.0221
0.0610
2.7635
Jasmine Tea
0.5575 0.6149 1.3650 1.5730 1.2243 1.2791
0.0517
0.1134
2.1936
Tieh-Kuan-Yin Tea
0.3119 0.3908 0.7630 1.0450 1.2232 1.3369
0.0509
0.1240
2.4343
Control
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Measurement/ control system design

To maintain the performance in real manufacturing situation.

Performance monitoring and parameter modification on the arrival of new
batch of tea.

Considering the influence of difference between batches
𝑌 = 𝐹 𝑋 + 𝑋𝑏 + 𝜀𝑡′
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Where 𝑋𝑏 is the factor of batches, which can regarded as constant for same batch,
𝑈𝑆𝐿 − 𝐿𝑆𝐿
𝑍𝑠𝑡 =
2
2 𝜎 ′ 2𝑡 + 𝜎𝑏2 + 𝑁
𝑖=1 𝐹 𝑖 − 𝐸
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A
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Equipment-a device that can solve the
problem
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A
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Equipment-a device that can solve the
problem
Equipment-inside view
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Conclusion
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
We should chance the tea leave every time
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Apply 6 boxes designed

Solve costly problem

Maintain the relatively stable level of tea Polyphenol
Some discussions
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The definition of our quality is the variance of Tea Polyphenols’
concentration only in our work.
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Further study can be focused on how many blocks we should have in the
device we designed so that the level of Tea Polyphenols can meet the
standards, which is too time consuming for us considering the experiment we
already made.
Our study is a very practical one, not so theoretical.