Journal of Engineering Research
Abstract
In machining operations, jigs and fixtures are considered as work-holding devices that aim to increase the production rate via eliminating the time necessary to individual markings and measurement-based settings. Instead, the accuracy of the machined feature become dependent only on the accuracy of the used jig/fixture which is controlled through its tolerances. In practice, several methods are used to assign those tolerances; nevertheless, none of these methods consider the total accumulated error resulting from the deviations of both the jig/fixture and workpiece dimensions from their respective nominal values. In this article, the total error expected from the well-known post jig which is usually used for drilling hole patterns in flange mount workpieces is analysed. The analysis considers the workpiece dimensions and tolerances, the jig dimensions, the cutting tool, and the differential thermal expansion error between the jig and the workpiece. As a conclusion, the positional error can be considered, in general, as the superposition of clearances between the mating surfaces of the jig/workpiece/tool parts and the initial differential thermal expansion error. This analysis can be used for assessing the maximum expected error from an existing jig and its suitability for a specific workpiece. If it used in reverse, the analysis can be useful in assigning the appropriate tolerances to the jig dimensions that guarantee the compliance of the error to the tolerance limits of the workpiece.
Recommended Citation
Hawam, Ahmed
(2023)
"The Maximum Positional Error of Circularly Distributed Holes Drilled with the Assistance of a Post Jig,"
Journal of Engineering Research: Vol. 7:
Iss.
1, Article 14.
Available at:
https://digitalcommons.aaru.edu.jo/erjeng/vol7/iss1/14