Interferometry based flatness gages have an inherent deficiency: they are incremental devices. That is, the reading for a single data point depends on the readings of its immediate adjacent data points. Any discontinuity will cause the device to lose its datum. If you have parts with surface discontinuity and you are looking for a flatness gage, conduct the following test to verify that the gages you have in mind can do the job right.

	Step 1: Create a flat surface on a piece of metal.	OG Technology has done such a test on interferometry gages with assistance from major U.S. manufacturers. Evidence shows that interferometry gages are incapable of detecting the recess due to the discontinuity (the grooves). In contrast, the OG™ flatness system is an absolute measurement device. Every single data reading is based on the same datum, the optical flat surface, and is independent of the readings of other data points. Therefore, OG™ systems can accurately measure parts with surface discontinuity.
	Step 2: Create two grooves about 1mm deep and 1mm wide.
	Step 3: Mill or lap off one of the four footings by 5 to 10 microns. Put the finished part on the flatness gage to see if your gage recognizes the recess.

Return to The OG™ 100 main page

OG TECHNOLOGIES, INC.
Ann Arbor, Michigan
(734) 973-7500

Write to us at sales@ogtechnologies.com for further information.

Copyright ©1998-2004 OG Technologies, Inc.
All Rights Reserved.
No part of this publication may be duplicated or redistributed without prior consent from the publishers.
OG Technologies, Inc., 4480 Varsity Drive, Suite G, Ann Arbor, MI 48108