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Clearing up the use of "T.I.R." in the Steel Supply Industry

2003

My question is one that I, and many others, have been trying to figure out for quite some time. We are in the Steel Service Center industry, we supply (among other product lines) Turned and Polished round bar stock (predominantly 12' to 24' in length, and anywhere from 1/2" to 6" in diameter) to various Centerless Grinding shops across the country. We have noticed that "in the industry", the standard straightness to be supplied to a grinding facility is a straightness specification of 1/32" in 5'. How do the MAJORITY of users measure this? Aside from the method of days gone by, using a straight-edge on a 5' portion of a bar, we now use a reading termed "T.I.R.", which stands for Total Indicated Reading. How is this supposed to be set-up and used? This practice employs the use of V-rolls strategically placed under portions of the bar, the bar is spun, and reading are measured just off the ends and off the middle of the bar using a dial indicator. I have contacted many facilities to see they are performing this T.I.R. reading, but it appears everyone is doing it differently. The interpretation of what should be read off the dial indicators varies considerably. How can all this variation be accepted as correct? Is there a standard way of measuring this T.I.R.? If there is, can you show an example from start to finish and show the readings that should be "acceptable"?

Thank you, in advance, for your help.

Allen Flores
- Hammond, Indiana, USA