Quality Engineering ( 2181920 )

Topic : Steps In Experimental Design

Branch :- Mechanical 8th B3

Prepared By:-130120119126- Pandya Kartik

The design of experiments (DOE) is the design of any task that aims to describe or explain the variation of information under conditions that are hypothesized to reflect the variation. 

It is an efficient procedure for planning experiments in which series of tests are premediated in which planned changes are made to the input variables of a process of system and effects of those changes on to the output are assessed to develop valid and objective conclusion.

DOE is the procedure of measuring the changes of input parameters on to the output parameters.

1) Controllable : Ingredients for tea(water, milk, sugar, tea leaves, etc.) can

be termed as controlled parameters. 2) Uncontrollable : Mixing methods or sequencing methods are uncontrolled variables which vary from person to person.

One Factor Designs : These are the designs where only one factor is under investigation, and the objective is to determine whether the response is significantly different at different factor levels.

On the other hand, data from tests where the factor Is quantitative (e.g. temperature, voltage, load, etc.) can be used for both effect investigation and prediction, provided that sufficient data are available

2) Factorial Designs : In factorial designs, multiple factors are investigated simultaneously during the test.

General Full Factorial Designs-In general full factorial designs, each factor can have a different number of levels, and the factors can be quantitative, qualitative or both.

Two Level Full Factorial Designs These are factorial designs where the number of levels for

each factor is restricted to two.

Restricting the levels to two and running a full factorial experiment reduces the number of treatments (compared to a general full factorial experiment) and allows for the investigation of all the factors and all their interactions.

Two Level Fractional Factorial Designs This is a special category of two level designs where not

all factor level combinations are considered and the experimenter can choose which combinations are to be excluded. Based on the excluded combinations, certain interactions cannot be determined.

Taguchi’s Orthogonal Arrays Taguchi’s orthogonal arrays are highly fractional designs,

used to estimate main effects using only a few experimental runs.

These designs are not only applicable to two level factorial experiments, but also can investigate main effects when factors have more than two levels.

Designs are also available to investigate main effects for certain mixed level experiments where the factors included do not have the same number of levels.