IPC-TM-650 EN 2022 试验方法--.pdf - 第48页

The sc orecard shows four dif ferent sets of ca lculations. This array of calculations reﬂects dif ferent approaches many ﬁnd useful. The ﬁrst section shows a summary of t he variability calculations. The t able shows ca…

The next calculation table shows, for each test condition, the average of all sample measurements for each repetition.

The ﬁnal table shows the overall average of all repetitions of all measurements across all test conditions.

Averages:

Condition

1 2 3 4 5 6 7 8 9 10

Readings

Set 1 0.83200 0.786 0.825

Set 2 0.836 0.763 0.832

Set 3

Set 4

Set 5

Op Avg 0.834 0.7745 0.8285

Absolute difference of condition averages

0.0595

Measurement Precision Study: Data Entry Sheet

Sample Sample Sample Sample Sample Sample Sample Sample Sample Sample

1 2 3 4 5 6 7 8 9 10

1 1 0.62 0.99 0.82 0.85 0.59 1.02 0.97 0.85 1 0.61

2 0.66 1 0.81 0.89 0.48

1.03 0.97 0.82 1 0.7

2 1 0.53 1.05 0.8 0.83 0.39 1.04 0.97

0.73

0.98 0.54

2 0.53 0.93 0.77 0.76 0.4 1.08 0.91

0.7 0.95 0.6

Condition

Station 1

Station 2

Reading

Average of each set of readings for each test condition

Sample 1 2 3 4 5 6

8 9

Avg 0.56667

1.00667 0.795

0.82167

0.46667

1.03833

0.95667 0.785

1.00333

0.68333

Average of sample averages

0.81233

Range of sample averages

0.57167

Measurement Precision Study: Data Entry Sheet

Sample Sample Sample Sample

Sample Sample Sample Sample Sample Sample

1 2 3 4 5 6 7 8 9 10

1 1 0.62 0.99 0.82 0.85 0.59 1.02

0.97 0.85

1 0.61

0.66 1 0.81 0.89 0.48 1.03 0.97 0.82 1 0.7

1 0.53 1.05 0.8 0.83 0.39 1.04

0.97 0.73

0.98

0.54

2 0.53 0.93 0.77 0.76 0.4 1.08

0.91 0.7 0.95

0.6

3 1 0.51 1.05 0.8 0.79

0.45 1.01 0.96 0.8 1.04

0.84

2 0.55 1.02 0.77

0.81

0.49 1.05 0.96 0.81 1.05

0.81

Condition

Station 3

Station 1

Station 2

Reading

Average of all readings

For each sample

January

2003

Users

Guide

—

The scorecard shows four different sets of calculations. This array of calculations reﬂects different approaches many ﬁnd

useful.

The ﬁrst section shows a summary of the variability calculations. The table shows calculated standard deviations. Starting

at the bottom, the table shows the total observed variation. Next the total variation is split into two portions, the process

variation and the total measurement variation, called measurement R&r. Process variation reﬂects differences in product per-

formance. The measurement variation reﬂects just differences in the measurement of this performance. The top two numbers

split the measurement variation into two portions, repeatability and reproducibility. The repeatability refers to variation

within a test condition. The reproducibility refers to variation between test conditions. This split between repeatability and

reproducibility can provide some vital hints to help diagnose possible causes.

From this table, it is known that the process capability is as follows:

Process average, X-bar = 0.812

Process standard deviation, S

= 0.179

The measurement precision is:

Measurement variability, S

R&r

= 0.043

Measurement Precision Study: Scorecard

Variability Summary

Remarks

0.03076

Standard deviation of the within condition variation

0.03038

Standard deviation of the between condition variation

0.04324

Standard deviation of the measurement process

0.17983

Standard deviation of the product variation

0.18495

Standard deviation of the total observed variation

0.81233

Average of all product measurements taken during study

Comparison to Specifications

(Only used when both specifications exist)

% Repeatability 39.6067 Percent of specification width used by repeatability error

39.1143 Percent of specification width used by reproducibility error

% Measurement R&r 55.6652

Percent of specification width used by measurement error

Compared to the specification limits, the precision of

this measurement:

Comparison to Total Variation

% Repeatability 2.76653 Percent of total variability used by repeatability error

% Reproducibility

2.69817

Percent of total variability used by reproducibility error

% Measurement R&r

5.46469

Percent of total variability used by measurement error

Compared to the total variability, the precision of

this measurement:

Measurement Tolerance

Units

On the basis of this study, there is a 99% chance that

this interval around the measured product performance

will contain the actual product performance level.

Needs improvement

Is adequate

Product Average

+/- 0.111243938

% Reproducibility

Repeatability

Reproducibility

Measurement R&r

Process std dev

Total Variability

Users

Guide

January

2003

Scorecard

The next table in the scorecard is shown below. It compares the measurement variation to the speciﬁcations for this prod-

uct. This table will only have numbers in it if there are two speciﬁcations. In this example, there are two specs, so the table

is complete.

The numbers in the table are percentages. The calculations show what portion of the speciﬁcation width is used up by mea-

surement error. The total measurement variability, called S

R&r

, consumes 55% of the speciﬁcation width. This is higher than

is considered acceptable. A good measurement would consume less than 10% of the spec width. An unacceptable measure-

ment would consume more than 33% of the spec width. Note that this conclusion is conﬁrmed by the dialog box at the bot-

tom of the table.

The graph plainly shows that an unacceptable number of the gaskets measured will fail, and that this failure rate is driven

by the measurement error. The process capability must also be improved, but the measurement must be improved before one

can be sure that measurements will be precise enough to reﬂect true product performance. To help diagnose the cause of the

measurement variation, the repeatability and reproducibility estimates are included. In this example the measurement varia-

tion is roughly equally split between within and between test condition sources. Therefore there may be several sources of

variation, with no one dominant cause.

A graph is often more compelling than the numbers. If one graphs the total observed variation and process variation as nor-

mal curves and superimpose the spec limits, the following graph would emerge:

This graph is prepared by creating normal curves which center on the overall product average, and extend out three times

the applicable standard deviation in each direction. For the total observed variation, the total variation was used. For the

process capability curve the product variability was used.

Comparison to Specifications

(Only used when both specifications exist)

% Repeatability

39.6067 Percent of specification width used by repeatability error

39.1143

Percent of specification width used by reproducibility error

% Measurement R&r 55.6652

Percent of specification width used by measurement error

Compared to the specification limits, the precision of

this measurement:

Needs improvement

% Reproducibility

0.2 0.4 0.6 0.8 1.0 1.2 1.4

Spec

limits

Total

observed

variation

Process

capability

January

2003

Users

Guide