PROCESS DRIFT

AN EXAMPLE OF SUBSTANCE OF PAPER AS

CTP

Process CTP Measured by Operator A Over a Period of Time – Day 1

Operator A Day 1

0 2 4 6 8 10

1

2

3

4

5

6

The Same CTP Measured By Operator B Over Same Time – Day 1

Operator B Day 1

0 5 10 15

1

2

3

4

5

6

The Same CTP Measured By Operator C Over Same Period Of Time the Same Day

Operator C Day 1

0 2 4 6 8 10

1

2

3

4

5

6

Same CTP Measured By Operator A on the 2nd Day Over The Same Period Of

TimeOperator A Day 2

0 2 4 6 8 10

1

2

3

4

5

6

The Same CTP Measured on 2nd Day By Operator B Over Same Time

Operator B Day 2

0 2 4 6 8 10

1

2

3

4

5

6

The Same CTP Measured Over The Same Period Of Time on 2nd Day

Operator C Day 2

0 2 4 6 8 10 12

1

2

3

4

5

6

The Same CTP Measured By Operator A on the 3rd Day

Operator A Day 3

0 2 4 6 8

1

2

3

4

5

6

CTP Measured By Operator B the 3rd Day

Operator B Day 3

0 2 4 6 8

1

2

3

4

5

6

CTP Measured By Operator C on the 3rd Day Over Same Time

Operator C Day 3

0 1 2 3 4 5 6

1

2

3

4

5

6

OVERALL PROCESSCTP PROCESS DRIFT HISTOGRAM

0

2

4

6

8

10

12

14

16

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52TIME(HOURLY SAMPLING)

FREQ

UEN

CY

OPERATOR A

OVERALL PROCESSCTP PROCESS DRIFT HISTOGRAM

0 2 4 6 8 10 12 14 16

1

4

7

10

13

16

19

22

25

28

31

34

37

40

43

46

49

52

TIM

E(H

OU

RLY

SA

MPL

ING

)

FREQUENCY

CONCLUSIONS• One can look at the Process Variation

– over a same period of time on the same day by different operators.

– by the same operator at different periods of time on different days.

• This is called Process Drift, which can provide an approximate estimate of how well the process is centered towards its target.

• One can stabilize the process by taking corrective actions for special cause variations visiting the process by process standardization & standard operating procedures.