16-05-2012, 03:24 PM
Two-grade fuzzy synthetic decision-making system with use of an
analytic hierarchy
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Introduction
Cutting and grinding fluids are widely used in machining
and grinding. Because of their negative effects on
health, safety and environment, legislation and public
environmental concerns now have great impacts on their
development. Dry machining and minimum quantity
lubrication (MQL) machining have been successfully
applied in some kinds of metal cutting, drilling, milling
and reaming processes [1]. On the other hand, in grinding
processes, it is very difficult to get good results without
the help of grinding fluids because of the great
amount of heat generated during grinding. As for MQL
grinding, although it is in the ascendant, there is a long
way to go before it can be carried into applications in
workshops. Therefore, research on the composition, supply
techniques, cleaning and maintenance of grinding
fluids is still very active at the present time [2].
First-grade evaluation and check of algorithm reliability
As has been already stated, the results in the firstgrade
evaluation are calculated with five couples of
fuzzy algorithms. Since every algorithm represents a different
principle of information handling, five kinds of
different operating results are achieved for every grinding
fluid. It is very important to process the operating
results to make them more reliable. In order to prevent
the extreme action of an algorithm from bringing deviation
to the results, the sum of the square of deviations
D(p) is adopted to judge the reliability of the algorithms.
For the ith grinding fluid, assume that the membership
degrees obtained by using the different algorithms are
mp(i) (p=1, 2,…, 5), which are membership degrees of
the grinding fluids belong to v1 (goodness).
Conclusions
1. The factor weights of the first-grade evaluation were
determined by AHP, which can eliminate the subjective
component of experts’ knowledge, and can easily
be expressed in a quantitative form. The factor
weights of the second-grade evaluation are determined
by the results of the first-grade evaluation.