Shaft taper fit - area of contact 3

[TrevorH]

Looking through various EN and ISO standards has not helped. If the shaft or hub is blued and fitted together [rotated] a percentage area of the other component is marked.
I am looking for guidance on what would be an acceptable marked area? Some publications for machine tool spindles state 80%! Is there any basis for this or other values?
The actual taper is for a replacement hub with a 1/10 taper at 190 dia, at the small end, x 280 long and is used to support and fix a "disk" of 4000 kg.

 

[ornerynorsk]

On something of this size, a machinist or job shop should be able to get nearly full contact. 280 mm long can be indicated to a taper deviation of a thousandth or less quite easily. It's actually more difficult to get a line-to-line fitup the smaller the part becomes, so you should really have no trouble with this.

 

[JJPellin]

Our standard for contact on taper fits is 80 percent minimum if there is a drive key and 90 percent minimum if there is no drive key. Our typically application would be a taper fit coupling hub on a piece of turbo-machinery. Most of these applications are in the 1000 to 20000 HP range on large pumps, compressors, steam turbines and gearboxes. The contact percent requirements are called out by the manufacturers of the equipment. I suspect that this may be dictated by AGMA or API standards, but was not able to find the specific reference. Using precision machining techniques and the option of the use of tapered lapping tools, it should be easy to achieve these requirements.

Johnny Pellin

 

[Fugeguy]

On medium speed centrifuges we used 90% contact new and below 70% required rework.

 

[TrevorH]

Thanks for those who replied - much appreciated. I have not been able to find any publication with guidance/rules on contact area requirements yet!.

 

[Tmoose]

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http://www.riverhawk.com/prg.php

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http://www.spindlegrind.com/inspection.htm

"When we regrind the seat we typically get 95-100% contact. Less than 70% should be considered in need of regrinding. Also note where the contact is. It should be evenly around the seat. A little heavier contact on the large end is acceptable, but heavier contact in the small end is not good. This is typical of a bellmouth condition, caused by normal wear, and should be reground.

Inspection with an air gage will tell you if the gage is seating properly. But, it will not tell you what the problem is, if it is not. For this reason I prefer to use bluing and plug gage."

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http://www.spindles.org/regrinding.asp

"Grinding continues until an acceptable level of taper contact has been achieved (usually no less than 90 percent contact and in most cases closer to 100 percent). At this point the spindle taper grinding process is complete. "

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http://www.edmundsgages.com/technical8.htm

 

[unclesyd]

Taken from the website of Riverhawk posted by Tmoose.


"Meets or Exceeds API 671 and ISO 10442 requirements"