787 production delay question

http://seattletimes.nwsource.com/html/localnews/2010498665_apwaboeing787tests1stldwritethru.html
according to this ill-fitting parts are causing delays in the 787; I
am wondering how can this be so, especially in aerospace;CAD reference geometries, iso standardization, instrument certification etc. should have eliminated any fit problems- so how can these screw ups happen ?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 12/13/2009 1:34 PM, raamman wrote:

http://seattletimes.nwsource.com/html/localnews/2010498665_apwaboeing787tests1stldwritethru.html
As you know, in the "old" days, things were fit together with a fudge factor (manual riveting etc). The 787 is a "click together" all the major pieces must line up exactly. Most of the joints are robot drilled and riveted I believe. So yes, if everyone is making their parts using the master model... in theory it should workout. But as you also know, these parts are made most times by the lowest bidder. Plus, there is no real receiving inspection of large airframe parts at Boeing till it's on the stand waiting to be assembled. It is "assumed" the vendor has done it right. I would think 75 percent of Boeing's machined parts are outsourced. You lose control - even with all the standards.
-- Bill
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

With assemblies as large as an airframe, even if they are correct when they leave the factory ( subcontractor) are they still perfect by the time they get top assembly? Some sagging and distortion may occur during shipping and handling.
And secondly, is there any allowance for fits built into the design? I once had a customer where everything was designed to the "nominal" and standard tolerances. If you didn't know how all the parts were intended to fit, and make sure you were on the correct side of the tolerance band, there was no way it was going to go together once you built it.. Not sure how to make that clear.. The solid models all fit together correctly, but if the parts were made to standard tolerances they would not fit. Of course the solid model was always the "perfect" size.. Real parts had to made to one side of the tolerance band or they would not fit.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 12/13/2009 4:50 PM, Half-nutz wrote:

Some great videos of the assembly:
http://www.youtube.com/watch?v=_GDqxnahwbk&feature=related

A LOT of composite manufacturing issues for sure!
-- Bill
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Sun, 13 Dec 2009 16:50:37 -0800 (PST) did write/type or cause to appear in alt.machines.cnc the following:

    One question that I have no idea if it still applies: are tolerances when expressed in metric dimensions "tighter" or "looser" than when converted to / from feet and inches?
pyotr
- pyotr filipivich We will drink no whiskey before its nine. It's eight fifty eight. Close enough!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

well, the shop where I worked worked in imperial units, but metric CAD files and the appropiate tolerance was converted to imperial on drawings given to the shop to help facilitate production and limit conversion error possibility to the single conversion made.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Thanks everyone for your input; but I am still perplexed- I have worked checking CAD for automotive T&D and the tolerances are always clear, H7 being standard, in my experience as I recall; and even small shops recognize the need and importance of certified instrumentation, qualified CMM operators etc. These aerospace contracts are not to be sneezed at, they are lucrative. The parts are not being stamped; they are molded and/or CNCd to precise tolerances- now, I understand that material removal will cause deformation, but no one roughs and finishes to one side before going to another side right ? and the part still has to pass inpection.I'm fairly sure they would have jigs set up to help with assembly to prevent components drifting out of required locations and to help ensure there is no undue stress that could cause a part to bend or warp excessively' and that shop temperatures will all be within a fairly moderate comfort zone- so again, even temperature variation should not cause such problematic fit to excessively delay the project- all my opinion, but I don't think any of these points are unreasonable.I know some members here have done aerospace components so I am hoping to hear of any further insight into this. Thank you.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 12/14/2009 10:25 AM, raamman wrote:

I've machined a lot of aerospace parts so... The deal is the parts are big. Most times they are inspected in some sort of at least slightly restrained condition. Not always but, many times. Also, even unrestrained, the parts may sag due to their sheer size during assembly.
Since very few parts are actually made at Boeing, they are source inspected at the vendors facility under the watchful eye of the Boeing Source Inspector(s). Once a couple are done, they may not require source on some of the following parts. Maybe something slips by. It's very hard to factor all the variables in unless you want to spend more time and money. I know, everyone says the designers should be able to handle this but there are deadlines for them as well. The big factor to include with the 787 is all the composite parts. They are some of the biggest ever assembled. Much more unforgiving than sheet metal. If you watched them assemble an older fuselage with sheet metal, you'll immediately see the difference. It looks quite crude really! <g>
One other poster brought up a BIG factor as well, hard to find experienced aerospace engineers. I mean, how many folks would risk $60-$100k in school loans to get into the "lucrative" <note sarcasm> field of aerospace. I wouldn't.
-- Bill
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Thanks Bill- that does make things a lot clearer for me. I stand by my lucrative statement- every sucessful shop owner I've met have the trappings of a considerable income- guess some just don't know how to bid wisely
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Dec 2009 12:01:08 -0800 did write/type or cause to appear in alt.machines.cnc the following:

    I had the unfortunate experience of talking with a friend after church yesterday. He told me that whereas "in the old days" (the 80's) we were told to expect to change careers between four and six times in our working life, now the expectations are to expect upwards of ten career changes. By "career change" is meant that you will be changing fields completely. Not a case of being a machinist in an aerospace company an then going to work for a car company. No, the expectation is that you'll be switching trades completely. "Machinist" to "Woodworker" to "Customer Service" to Office worker, and so on.     So, ten career changes over a forty year "career" is 48 months. Barely long enough to "learn the trade", in some trades.     And companies are sacking long term employees as a cost control measure. 'You've been here 3 years, you are starting to cost us too much money.'     Then they wonder why they have problems producing a quality product, or getting quality workers.
    This problem isn't "new" - the Army decided a long time ago to go with an "up or out" policy. That you had to be promoted regularly, or you would be discharged. Sounds great, until you realize that some people just want to command a company, not a battalion, or division. Or that having commanders who have, however inadvertently, "specialized" in small unit operations provide you with a core who know what they are doing (as much as any one can) in case of war, or a need for cadre to expand the next level "up". - pyotr filipivich We will drink no whiskey before its nine. It's eight fifty eight. Close enough!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

6 career changes and I'm 46, how's that?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 12/14/2009 7:37 PM, raamman wrote:

One long career. Started as Machinist ended up an nc programmer. 13 job changes starting at age 19... I'm 51 now and trying out the self employed thing.
-- Bill
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Dec 2009 21:44:04 -0800 did write/type or cause to appear in alt.machines.cnc the following:

    Mazel. That's what I'd like to have done. But I didn't start the machinist classes till I was 47. And I'm not sure what would qualify as a "career" and what was just "any available job."
tschus pyotr
- pyotr filipivich We will drink no whiskey before its nine. It's eight fifty eight. Close enough!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

wow, that's late to get into; how's that working out ? I found that compared to youger guys I didn't have as much energy ( and I was very active and healthy before ); now my eyes are going, I am having trouble reading fine print, and I have to be cautious as my back goes out if I'm not.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 12/15/2009 7:15 AM, raamman wrote:

Being on the floor is definitely a "younger" mans game. Back in the days of conventional machining not so much. I used to work with a lot of guys in their 50's. Now, most of the floor guys "machinists" are young and setup/run several machines due to process control. I don't think I'd do it all over today. The only way to stay on top is to "out brain" the others. Working fast just makes you older...<g>
-- Bill
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

There's always government work:
http://jobs.workopolis.com/jobshome/db/citybrampton.job_posting?pi_job_id=9477114&pi_search_id=614721994&pi_sort=POST_DATE&pi_curjob=1&pi_maxjob=7
(BELLY DANCER (Part-time) (9477114)
Job Type: Part Time Location: Brampton; Industry: Government Year(s) of Experience: 1 Number Of Positions: 1 Date Posted: Dec 15, 2009
Belly Dancer Needed
If you are an experienced belly dancer with one year experience and is available days and evenings, please apply by sending your resume by Jan 10, 2010.)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
15 Dec 2009 07:15:04 -0800 (PST) did write/type or cause to appear in alt.machines.cnc the following:

    It was going. That bit about ""old age and treachery?" Or "Old age and general experience", rather. I've learned the difference between working hard, and working smart. I still tootleth my own horn for the time I got what was scheduled to take 12 hours completed in 6. But I just didn't want to face that pile of crap when I got back tomorrow, so, lets set this up for production. Anybody who got in the way just got run over .... "Well begun is half done."     Hey, there's a reason my old boss was so fussy. I'm not that fussy, but ... I learned those lessons too.     So the rest is just "application".
    But I still would like to meet that proverbial over sexed librarian, who's Mom runs the machine shop, and her Daddy has the book store...
pyotr
- pyotr filipivich We will drink no whiskey before its nine. It's eight fifty eight. Close enough!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
BillT wrote:

My very best wishes to you in your efforts at self employment. It's a tough row to hoe in this economy and I have the utmost respect for anyone attempting it.
Started as a TIG welder, but in sheet metal job shops there can be quite a mix and often there are opportunities to work in other areas. That I did, moving into fabricating, machining, sheet metal, programming, and design work, before striking out on my own and managing to self employ for 13 years in an area hardly noted for it's manufacturing. I consider it one long career in more or less the same trade. 11 jobs total over a 34 year span. Longest job held, 9-1/2 years.
Just learned I'm at the top of a very short list to be interviewed for what would be the job of my dreams. I'd not only be able to use the range of my skills, but will find myself surrounded by very talented people. That is to say, in a position to learn even more. It's a defense related job and my friend that's been working to get me in there still doesn't talk about -what- they make, just operations performed. Sounds like I'll be able to float between machining, sheetmetal, and welding. With a chance to pick up some certifications in welding, in addition to learning to paint and powercoat. Small shop, lots of work is carried from start to finish by the same person. My buddy has been there 6 years and he's the junior, some guys have been there 25+ years. So I fully expect to buck the trend and stay in my chosen field for as long as I'm able to work.
Looks like Oz is a ways off, and in fact, if I do land this job, my wife will likely go back to our original plans and immigrate here. She's tired of working in the health care field and wants to attend a culinary school here. My waistline isn't so sure that's a good thing but my stomach is fully behind it!
Jon
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
14 Dec 2009 19:37:37 -0800 (PST) did write/type or cause to appear in alt.machines.cnc the following:

    Six down, four to go, I guess.
    While it is good to be flexible, eventually, the workforce will be composed of "Jacks of all trades and master of none" - and more jobs/industries will be outsourced.
fnord
pyotr
- pyotr filipivich We will drink no whiskey before its nine. It's eight fifty eight. Close enough!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 14 Dec 2009 19:37:37 -0800 (PST), raamman
<snip>

<snip> ======While this does indeed seem to be the case in increasing numbers of American businesses, it also appears to grossly violate Gladwell's 10,000 hour rule as detailed in his book "Outliers".
It also appears to be another yet example of a trend that results in observation that is made repeatedly in the analysis and literature of the current socio-economic problems: "[fill in the blank] makes perfect sense and is economically logical for an individual in the short-term, but it is a disaster collectively in the long-term."
For a quick review see http://en.wikipedia.org/wiki/Outliers_%28book%29 <snip> A common theme that appears throughout Outliers is the "10,000-Hour Rule". Gladwell claims that greatness requires enormous time, using the source of The Beatles' musical talents and Gates' computer savvy as examples.[3] The Beatles performed live in Hamburg, Germany over 1,200 times from 1960 to 1964, amassing more than 10,000 hours of playing time, therefore meeting the 10,000-Hour Rule. Gladwell asserts that all of the time The Beatles spent performing shaped their talent, "so by the time they returned to England from Hamburg, Germany, 'they sounded like no one else. It was the making of them.'"[3] Gates met the 10,000-Hour Rule when he gained access to a high school computer in 1968 at the age of 13, and spent 10,000 hours programming on it. In Outliers, Gladwell interviews Gates, who says that unique access to a computer at a time when they were not commonplace helped him succeed. Without that access, Gladwell states that Gates would still be "a highly intelligent, driven, charming person and a successful professional", but that he might not be worth US$50 billion.[3] Gladwell explains that reaching the 10,000-Hour Rule, which he considers the key to success in any field, is simply a matter of practicing a specific task that can be accomplished with 20 hours of work a week for 10 years. He also notes that he himself took exactly 10 years to meet the 10,000-Hour Rule, during his brief tenure at The American Spectator and his more recent job at The Washington Post.[2] <snip>
To read the book contact your local library or (Amazon.com product link shortened)
Some closely related topics are "work simplification," "specialization of labor," and "deskilling." http://en.wikipedia.org/wiki/Division_of_labour
http://en.wikipedia.org/wiki/Deskilling http://wox.sagepub.com/cgi/content/abstract/14/3/323 http://generationbubble.com/2009/08/06/the-knack-and-how-to-forget-it-an-inquiry-into-consumption-deskilling / http://www.eric.ed.gov/ERICWebPortal/custom/portlets/recordDetails/detailmini.jsp?_nfpb=true&_&ERICExtSearch_SearchValue_0=EJ357624&ERICExtSearch_SearchType_0=no&accno=EJ357624
http://legalcatch.wordpress.com/2007/09/17/specialization-of-labor-alienation /
A major problem is that high volume/mass production of identical products must be assumed to justify "deskilling," and "extreme labor specialization." It is precisely this that is rapidly being abolished.
Unka George (George McDuffee) .............................. The past is a foreign country; they do things differently there. L. P. Hartley (1895-1972), British author. The Go-Between, Prologue (1953).
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.