Aerospace Standard of hole quality evaluation

[Gonzalvich]

Hi all,

I am starting to do my Final Project at my University and I am having some problems for search Aerospace Standards, because it is too specific.

In particular, I need norms, or specifics standards about proves to measuring holes qualities with differents tecnics and process.

Somebody know something about this subject or know any specific webpage? I have searched on google and I have found some articles and catalogues but no more. In

http://www.sae.org

and in the free trial Aerospace Standard, I didn't find nothing about Hole Quality Evaluation.

Thanks in advance!

 

[rb1957]

i think you need to contact a local airplane manufacturer or modifier. these standards are company specific ... mind you i'm sure that they're pretty much the same !

Quando Omni Flunkus Moritati

 

[Gonzalvich]

Thanks rb1957!

I have tried to keep contact with some companies. I'm waiting response.

 

[WKTaylor]

Gonzalvich...

Be cautious... there is more to this question than meets the eye. Hole quality is a combination of MANY elements. Each company has worked hard to understand/control these issues in their manufacturing practices; and analyse how each element affects joint life [material fatigue, fastener failures, etc].

Hole size/shape held within very specific tolerances for each installed fastener type [bolts, rivets, hi-loks, blind rivets, blind-bolts, bushings, etc].

NOTE. Fastener "fit" in the hole is a critical element of fastener performance: loose/sloppy clearance fit, tight clearance fit, net fit [hole dia = fastener dia +/- small tolerance], light interference, medium interference, presence of burrs, etc.

Hole surface position accuracy [relative to other holes] and bore/countersink/counterbore/spotface angularity relative to the hole bore and/or surface.

Hole bore/lip/edge/countersink/counterbore/spotface surface roughness; and control of potential sources of scratching/gouging/friction damage during drilling/reaming/boring.

Fit-up between layers of fastened materials during drilling/reaming and fastening: Tightly pulled/clamped together or loosely stacked/gapped.

CAUTION. Various type materials [aluminum, magnesium, titanium, SSTL, Steel, Heat Resistant Alloys, etc] have very dissimilar drilling/reaming qualities. a stack-up of "soft" and hard/tough" metals is a bear to drill/ream accurately/smoothly since each layer reacts differently; and the soft materials are easily damaged/scored by the harder/tougher material shavings.

Hole inspection practices to ajudicate hole quality, etc.

A few quick bits of info that may be useful for starters.

Any [almost] liaison engineering training course.
Any modern commercial or military aircraft Structural Repair Manual [SRM]
ASME B46.1 SURFACE TEXTURE (SURFACE ROUGHNESS, WAVINESS AND LAY)
ASME Y14.NAS 618 FASTENER, RECOMMENDED SHANK, HOLE AND HEAD-TO-SHANK FILLET RADIUS LIMITS
NASM47195 RIVETS, BLIND, SELF-PLUGGING, PREPARATION FOR AND INSTALLATION OF
NASM47196 PREPARATION FOR AND INSTALLATION OF BUCK-TYPE RIVETS
NASM81177/1 FASTENERS, BLIND, HIGH STRENGTH, INSTALLATION FORMED, ALLOY STEEL; DESIGN AND USAGE LIMITATIONS FOR

Various fastener manufactuer websites that provide recommended hole preparation for specific type fasteners.Etc.

Have-to go back to work.

Regards, Wil Taylor

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