It is very difficult to measure the inner profile geometry of small holes of less than a millimeter in size, yet that geometry may be important for some manufacturing operations. This paper will present a method to measure key dimensional parameters of small holes used in a variety of applications from cooling to lubrication. Precision shaped holes can consist of a hole at some angle to the surface of the part and an area around the entrance to the hole for the purpose of diffusing the air or lubricant across the surface of the part to achieve the most effective performance. The drive towards smaller and more complex hole geometries means that previous methods such as conventional touch probes do not provide a good mapping in a time that can be used as part of production. The advanced designs of the holes means simple pin gages do not provide enough information. This paper will discuss tests of various methods considered for mapping small hole inner diameters, and present some sample results of a possible solution.

Date Published: 14 May 2015
PDF: 11 pages
Proc. SPIE 9489, Dimensional Optical Metrology and Inspection for Practical Applications IV, 94890M (14 May 2015); doi: 10.1117/12.2177362

Published in SPIE Proceedings Vol. 9489:
Dimensional Optical Metrology and Inspection for Practical Applications IV
Kevin G. Harding; Toru Yoshizawa, Editor(s)