Taper-Lok fatener group numbers

[JamesKuhlenberg]

I am new to forum, and I am not an engineer, but I have been in the aerospace industry for 32 yrs and my question has to do with the different group numbers and their definitions associated with taper-loks. I am sure there is a good reason for grouping them, but I'm not positive what that reason is. I have been told it has something to do with the all the different tools needed for the proper hole preparation. You would think that being standard, 1st or 2nd oversize would be sufficient callout on the tools . I would appreciate any light that could be shed on this subject. Thanks to any help I can get

 

[tbuelna]

Taper-Loks are very high performance fasteners, and they require precise machining of the tapered hole to ensure proper performance. The factory tooling systems provide precise depth control (+/- .001") of the tapered hole, and this is critical for producing the proper fit and preload of the installed taper-lok pins.

 

[Metalsmythe1977]

There are actually six groups (1-6) for each fastener series and they overlap as the overall fastener length grows: TL100 Nominal(Group 1,2,3), TL110 1st oversize(Group 2,3 4), TL130 2nd oversize (Group 3,4,5), and TL140 3rd oversize (Group 4,5,6). The cycle repeats at the next nominal size. While they are certainly a fine fastener from a fatigue standpoint; the installation process is extremely sensitive to several variables: personel experience and training, tooling, aircraft hole quality, and fastener tolerances. We have and will continue to spend many, many labor hours to succesfully comply with the tight tolerances required. Would rather use a straight interference fastener (Hi-Tigue) any day over a Taper-Lok.