rivet shaving
rivet shaving
(OP)
I am looking to get correct information on rivet shaving. I work for a Aerospace company in stockton ca. I know the process being used on winglets is incorrect. ME's and QE's dont want to deal with it.
It is my understanding the indents on the heads of a flush clinch rivets should still show and that the rivet shouldnt be shaved more than .010.
What is happening is the Techs are setting the rivets countersink low so the rivet will set high and then shave them flush leaving the dia. of the head now reduced, thus jeopardizing the integrity of the rivit as it was designed.
The parts I build are for corporate jets and do fall under SURFACE PROFILE (AIRFLOW) specs. Spoilerons and Winglets. I will replace a rivet I dont think is correct because I want to do the best I possibly can. I am working on a degree in Engineering, I want have the knowledge to not let this kind of laziness jeopardize apart I am involved in designing or building.
Please let me know if I am wrong.
BBrazil
It is my understanding the indents on the heads of a flush clinch rivets should still show and that the rivet shouldnt be shaved more than .010.
What is happening is the Techs are setting the rivets countersink low so the rivet will set high and then shave them flush leaving the dia. of the head now reduced, thus jeopardizing the integrity of the rivit as it was designed.
The parts I build are for corporate jets and do fall under SURFACE PROFILE (AIRFLOW) specs. Spoilerons and Winglets. I will replace a rivet I dont think is correct because I want to do the best I possibly can. I am working on a degree in Engineering, I want have the knowledge to not let this kind of laziness jeopardize apart I am involved in designing or building.
Please let me know if I am wrong.
BBrazil





RE: rivet shaving
RE: rivet shaving
To reiterate, some fasteners are designed with milling flush in mind. If it's done right it's fine.
RE: rivet shaving
What do You mean by "clinch rivet"??
Are these blind rivets or solid rivets??
If You are milling solid rivet heads then what is the design [certification] requirement for the rivet installation?
If you are milling blind rivet heads, then there are a heap-O-other troubles possible that would be considered major structural concnerns by ALL of the blind fastener manufacturers.
Note: I used to work for a company that had a policy of deliberately machining all countersinks to the depth of an NAS1097 [shear-head]; then installed only MS20426 flush-tension head solid rivets [sat way above flush when installed]; then every external rivet was microshaved flush to the skin; then every bare rivet head was brush-alodined. The process produced a "slick skin appearance" but took a lot of tedious man-hours.
When the company was going bankrupt due to the costs of manufacturing, and asked for cost-cutting ideas, I asked why don't we install the "new" NAS1097 rivets and eliminate all countersinking: would save hundreds of M-hours per acft. I got a cold stare and was told that the aircraft was certificated with the rivet-process "as-is" and that using NAS1097s might constitute a major revision to the design. My only answer to that reply was to [quietly] begin looking for a new job.
OH Yeah...
Regards, Wil Taylor
RE: rivet shaving
btw, installing 1097s in a 1097 CSK would reduce (eliminate?) the shaving hours (not the CSKing hours).
RE: rivet shaving
Yep... except it would have saved shaving AND brush-alodine Man-Hrs... not to mention all the environmental and health "issues" [we now know] regarding exosure to alodine.
Regards, Wil Taylor
RE: rivet shaving
RE: rivet shaving
RE: rivet shaving
I am aware that some rivets are designed to shave and some not to be shaved. This company does not hire qualified people, (they'd have to pay them to much)Most have no clue. I use the 1097 rivet on the spoilers I build and dont shave them. I set them where a quick scuff with some sandpaper cleans them up nicely. Just as you say "If its done right its fine"
RE: rivet shaving
Yes, a clinch rivet is a blind rivet. Blind rivet shaving does create tons of issues, most all negative. This is why I questioned the process, These parts are winglets. Fully exposed to high stresses. It s only obvious to me there is a potential risk in the way the riveting is performed but will anyone stand up to seriously looking at it.......NO!!! Really, I get the same kind of reaction as you did.
By the way, I am quietly lookig for another job. Unfortunately this isnt the best economic time to start a new job.
RE: rivet shaving
I finally figured-out what RB1957 meant when he said in reply to me "eliminate countersinking???"...
My hand was faster than my brain... again. obviously I meant to say NAS1097s [in proper countersinks] eliminate need for microshaving... not countersinking.
---------
BBrazil... a sneaky way to end run this problem may be to change blind Rivet P/Ns to accomodate the manufaturing style of Your group.
NAS9303 [aluminum sleeve, steel or CRES pin] and NAS9309 [monel bare or aluminum coated] are NOMINAL diameter rivets with a head style [shape/size when installed] very similar to the NAS1097. The 1/64" OS versions [NAS9305 and NAS9311] have a head-style that is slightly deeper than a 1097... but significantly shallower than the MS20426.
Also, my favorite: have You ever used, or even heard-of the blind rivet head style "flanged-dome head" [lovingly called the "Unisink" by CHERRY, NAS9306/NAS9312]? It combines a tiny countersink with a VERY low-height protruding head. Great for thin skin installation, with allowables that are essentially identical to the equivalent protruding head OS blinds [Ref procurement specs NAS1686, NAS1687].
Regards, Wil Taylor
RE: rivet shaving
RE: rivet shaving
RE: rivet shaving
RE: rivet shaving
It would appear to me that an audit by the FAA at your facility is overdue.
Especially if the items you have been complaining about were known to them, ( But you would not tell them, Right?)
B.E.
RE: rivet shaving
This company is a AS9200 Boeing certified facility and Audits happen every year. Its amazing how good the company can put certain programs under the radar.
I could lose my job if it was known i said anything. In this economy that wouldnt be a good thing for my family. I dont recall the FAA ever doing an Audit there, but you are right, its way overdue.