pg_0167

Process Improvement

5.4.

Analysis of DOE data

5.4.7.

Examples of DOE's

5.4.7.1.

Full factorial example

Data Source

This example

uses data from

a NIST high

performance

ceramics

experiment

This data set was taken from an experiment that was performed a few years ago at NIST (by Said

Jahanmir of the Ceramics Division in the Material Science and Engineering Laboratory). The

original analysis was performed primarily by Lisa Gill of the Statistical Engineering Division.

The example shown here is an independent analysis of a modified portion of the original data set.

The original data set was part of a high performance ceramics experiment with the goal of

characterizing the effect of grinding parameters on sintered reaction-bonded silicon nitride,

reaction bonded silicone nitride, and sintered silicon nitride.

Only modified data from the first of the 3 ceramic types (sintered reaction-bonded silicon nitride)

will be discussed in this illustrative example of a full factorial data analysis.

The reader may want to download the data as a

text file

and try using other software packages to

analyze the data.

Description of Experiment: Response and Factors

Response and

factor

variables used

in the

experiment

Purpose: To determine the effect of machining factors on ceramic strength

Response variable = mean (over 15 repetitions) of the ceramic strength

Number of observations = 32 (a complete 2

factorial design)

Response Variable Y = Mean (over 15 reps) of Ceramic Strength

Factor 1 = Table Speed (2 levels: slow (.025 m/s) and fast (.125 m/s))

Factor 2 = Down Feed Rate (2 levels: slow (.05 mm) and fast (.125 mm))

Factor 3 = Wheel Grit (2 levels: 140/170 and 80/100)

Factor 4 = Direction (2 levels: longitudinal and transverse)

Factor 5 = Batch (2 levels: 1 and 2)

Since two factors were qualitative (direction and batch) and it was reasonable to expect monotone

effects from the quantitative factors, no centerpoint runs were included.

5.4.7.1. Full factorial example

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