1. 7th International & 28th All India Manufacturing Technology , Design and Research Conference 2018
Anna University, Chennai – , India
13th -15th December 2018
AIMTDR 2018
CATEGORY:
MACHINING
Evaluation of Circularity and Sphericity from Coordinate Measurement Data
G.L. Samuel¹[ ORCID Number] and M.S. Shunmugam1*[ORCID Number]
1Manufacturing Engineering Section, Department of Mechanical Engineering,
Indian Institute of Technology Madras, Chennai , India
PAPER ID:
19919
INTRODUCTION
RESULTS AND DISCUSSION
Table 1. Results
The Computer Aided Inspection (CAI) procedures have gained a prominent role in the field of inspection.
The coordinate data from CMM combines the information on form as well as size and a suitable transformation.
In this paper, appropriate methods have been presented to handle the two and three-dimensional coordinate.
Sl. No.
xi mm
yi mm 1 2 3 4 5 6 7 8 9 10 11 12
OBJECTIVES
Fig. 1. Circularity error
Fig. 2. Sphericity error
To propose the methods for handling CMM and transformed data.
To validate methods using the data available in literature.
To evaluate various form errors
Fig. 3. Circularity error
OBSERVATIONS
The ANSI Dimensioning and Tolerance Standard Y14.5 [1] defines form tolerances of a component with reference to an ideal geometric feature and ISO standards [2] recommend the form to be evaluated based on the minimum zone concept.
The Data Sets in Table 1 shows the CMM data for circularity and sphericity features respectively. These data sets are taken to bring out the differences in ap-proaches to be followed for processing CMM data and transformed data.
The International Standard ISO 1101 [1] defines circularity error as the radial dis-tance between two concentric circles separated by minimum possible distance and containing all the measurement points on the given profile as shown in Fig. 1. How-ever, sphericity evaluation is to be done with reference to two concentric spheres con-taining all points of the data set and having the minimum separation as shown in Fig. 2.
The deviation of a point is expressed with reference to the limacon and limacoid (Ref. Fig. 3 and Fig. 4)
METHODOLOGY
In this paper, appropriate methods have been presented to handle the two and three-dimensional coordinate data obtained from CMMs.
Methods to directly arrive at the error value using CMM data have been suggested.
While evaluating the circularity error using CMM data directly a circle is considered as the assessment feature and while using the transformed data a limacon is considered.
Fig. 4. Sphericity error
CONCLUSIONS
REFERENCES
The CMM data contains both size and form information and hence circle/sphere is used as assessment feature and the normal deviations are to be considered.
The co-ordinate measurement data can be converted suitably by applying appropriate trans-formations and it can be further processed to evaluate the form errors.
As the size is suppressed and the profile is distorted while transforming, limacon/limacoid is used as assessment feature and linear deviation are to be considered.
By applying appropriate methods, the value of form error remains the same for a particular profile wheth- er the coordinate data (CMM data) or the transformed data is used for processing.
Murthy TSR, Abdin SZ (1980) Minimum zone evaluation of surfaces. International Journal of Machine Tool Design and Research, vol 20(2), pp doi.org/ / (80)
Samuel GL, Shunmugam MS (2000) Use of limacon and limacoid in evaluation of circulari-ty and sphericity errors. In Proceedings of the All India Manufacturing Technology Design and Research Conference, Chennai, India (pp ).
Jin L, YoshizawaT (2009) Handbook of Optical Metrology: Principles and Applications, 263.
Kanada T, Modern Metrology Concerns, InTech, (1995) 281 – 289.