Pugh Concept evaluation and selection matrix in mechanical design

How to create a Pugh selection matrix for multiple mechanical design concepts and how to evaluate with examples

Concept Creation and concept selection are thought intensive activities which require a good understanding of the problem in mechanical design process.

Pugh concept evaluation matrix helps to systematically analyse concepts based on certain criteria important for product or system.

Format

	Baseline	Design alternative
Criteria 1	0	+1
Criteria 2	0	-1
Criteria 3	0	0
Criteria 4	0	+1

Scores are given based on superiority of alternatives to the baseline design with +1 indicating better , -1 indicating worse and 0 indicating same

An example:

Design of a bracket for an awning for a window .

The awning is the protective covering above the outside of a windown which shields from wind, rain and sunshine .

The yellow part is the awning which is supported by a link blue in Concept 1 and Red in concept 2.

Pugh Concept evaluation and selection matrix

	Baseline (concept 1)	Alternative (concept 2)
Weight	0	-1
Ease of assembly	0	-1
Durability	0	+1
Rigidity	0	+2
Aesthetics	0	+1
Manufacturing and assembly	0	-1

Each criteria may not be equaly important. Depending on the relative importance of each a weightage may be given which sums up to 100 % .

Case study 2 :

Design of a a bracket to mount the bronze rod on the purple plate.

Concept 1 (baseline)

The mounting holes in the purple plate .

Alternative concept (sheet metal bracket) to perform same function :

Comparison of the two concept designs:

Pugh selection matrix

	Baseline (concept 1)	Alternative (sheet metal concept 2)	Remarks
Lightweight	0	+2	Much light weight design
Ease of assembly	0	-1	Difficulty of access of fasteners
Durability	0	-1	Solid block should be better in strength (to be evaluated)
Rigidity	0	0	Almost same
Manufacturing	0	-1	Requires more operation
Cost of production	0	+1	More bigger volumes cost can be lowered

Categories: Design process