Assessment of Form Tolerances by Least Square Method

Gopinath, L and Ravishankar, S (2014) Assessment of Form Tolerances by Least Square Method. In: International Conference On Trends in product Life Cycle, Modeling, Simulation and Synthesis PLMSS-2014, 06-08 January 2014, Vellore, Tamil Nadu, India.

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Abstract

Form tolerances are related to features that are not dependent on datum for reference, where the overall feature accomplishes form. Evaluation of form tolerance is done from the sample space data set, its distribution and measurement factors. Average value of deviation to assess the tolerance may give a quick picture of variation but shall not contribute to the characteristics of slope/fluctuations in the readings. The knowledge of the expected geometry achieved by best fit computation through any of the mathematical procedure provides the primary iterative step to define manufacturing variation. This paper discusses the best fit by Least Square Method by analyzing the data and deviations considered for the form tolerances such as Flatness, Circularity and Straightness. The standard mathematical definition for the validation of the form tolerances are drawn from the ASME Y14.5M standards. The case studies to evaluate the mathematical method are carried out for flatness on the surface plates, Circularity on Ring gauges and Straightness on a straight edge. The deviations of the points from the Gaussian geometry are compared against hard inspection methods and the reliability of the best fit by least square method is discussed against the BIS standards and its characteristics by a normal distribution curve.

Item Type: Conference or Workshop Item (Paper)
Subjects: ENGINEERING > Engineering (General)
ENGINEERING > Mechanical Engineering
Depositing User: Sri. S Raghavendra Rao
Date Deposited: 21 Apr 2014 10:54
Last Modified: 21 Apr 2014 10:54
URI: http://nal-ir.nal.res.in/id/eprint/11946

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