TIR

I have a very basic question for the list. In describing the runout for a chuck I have seen the letters TIR along with the runout value. I know this is talking about the runout but I was just curious what TIR stands for. Total Included Runout or Total Indicated Runout were the guesses we have come up with. Thanks for any replies on this. Rich W.

Where I work, I was told it stood for 'Total Indicator Reading'. Todd

It depends upon the application and your local conventions. For most of industry, it's "total indicated runout." That's the difference between the lowest and the highest dimensional values for a cylindrical part, measured all around its periphery, from center. It's also the same thing as "total indicated roundness," which is a corruption of "total indicated runout."

It's sometimes interpreted as "total indicator reading." This is a vague sort of definition. On cylindrical parts, it means about the same thing as above. On flat parts, it depends on what the guy who says it thinks he means by the expression. I've seen it used to mean the same thing as Rt ("R-sub-t," or total surface roughness), which is the dimension from the lowest valley to the highest peak over a given span of a part).

In the literature, it usually means "total indicated runout."

Ed Huntress

Thanks for the responses to my question. Rich W.

ANSI Y14.5, "Dimensioning and Tolerancing" agrees.

Ned Simmons

Big gold star, as either definition works find.

Two ways to measure runout..

1. How far out from center axis does the item vary. This as an example, is measured from a fixed point away from the axis
2. How far does the item varies in total. If you measured a bend, spinning, and it had .01 bend in it. it would measure .01 runout, but if you measured TIR, it would actually run out .02, as its covering that much territory as it spins. Often measureing a single point on a bent item will not give you a true indication, as it may be bent in more than one point..the end may be dead nuts, but the middle may be out .5 as an example.

Gunner

Cum catapultae proscriptae erunt tum soli proscript catapultas habebunt.

total indicator reading

This is how I've seen it used.

Basically this is the equivalent of "peak to peak" value when reading an electrical waveform - the largest large value, minus the smallest small value, that you see over some time.

Then there are various others like peak value, rms value, average value, etc. Most of them have analogs in the mechanical world as well.

But TIR means, what's the worst case scenario - what's the largest movement one can see?

Jim

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On Thu, 30 Oct 2003 14:38:35 +0000 (UTC), Todd Rich scribed:

All pretty much the same. Difference between Max and Min... So if you have +10 mils, -5 mils, the TIR reading is 5 mils... If you indicate

-15 mils to -20 mils the TIR is 5 mils.

Fred

In the first example, you mean 15 TIR, don't you?

John Martin

On 31 Oct 2003 20:05:45 GMT, snipped-for-privacy@aol.com (JMartin957) scribed:

Yes... My bad ;-)

Fred

As it was where I worked when I broke into the trade.

Harold

TIR Total Indicator Reading HTH