Process Capability Analysis and Process Analytical Technology

Process Capability Analysis and Process Analytical Technology

Presented by: Steven Walfish President, Statistical Outsourcing Services steven@

Agenda

? Introduction to Capability ? What is capability ? Histograms ? Normal Distribution

? Capability Indices ? Cp ? Cpk ? Pp ? Ppk

? Calculating Sigma ? Relating capability to percent nonconforming

? Capability with attribute data ? Defects per Million Opportunities (DPMO)

? Process Analytical Technology (PAT)

What is Capability?

? Process capability compares the output of an in-control process to the specification limits.

? The comparison is made by forming the ratio of the spread between the process specifications (the specification "width") to the spread of the process values, as measured by process standard deviation.

? A capable process is one where almost all the measurements fall inside the specification limits.

Graphical Representation

LSL

Mean = 75 SD = 0.3 USL = 73 USL = 77 6S = 1.8

USL

6S on each side of the mean to the specification limit.

73.2

73.8

74.4

75.0

75.6

76.2

76.8

Histogram

73.66 40

30

74.11 74.41 74.71

75.31 75.61 75.91

?1S (68.3%)

?2S (95.4%)

?3S (99.7%)

76.36

20

?4.5S (99.9993%)

10

Frequency

0

74.0

74.4

74.8

75.2

75.6

76.0

76.4

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