There is a balance between designing for function and designing for manufacture. To succeed you really need to achieve both.
Generally little point having the best functioning piece of kit in the world if it’s so expensive to make no one buys it/you can’t sell it at a profit. Likewise, not much point having something that’s cheap to manufacture but doesn’t work.
Sometimes you will compromise your function, or at least change its design, for the sake of manufacturability. Sometimes you have to tell manufacturing to suck it up and just do it like you designed. Difficult part sometimes is knowing which way to go.
From what you say it’s difficult to know where the balance lies with you at the moment. You’re making it all out to be manufacturing’s issue, and maybe it is (I’ve worked a place that had that issue sometimes), but maybe some aspects of your design could be easier to manufacture, or at least better suit their processes/equipment.
If you are getting them built OK in the US and just having trouble in Europe then Mikes suggestion sounds good, even better get your US manufacturing to talk to Europe.
If you only have it made in Europe then Mikes suggestion is still nice but might be prohibitively expensive. As Mint says try and find out what their capabilities are and start to design to them. Ask them to detail what they can weld, what they can form, what they can machine and how accurate etc. For instance, no point speccing lots of rolled/bent ¼ plate if the maximum thickness they can do is 1/8. Either you need to change your design, outsource this part of the manufacturing or get them better tools.
Also, can you get their input earlier in the design process? Do you have design reviews and if so do manufacturing contribute? While if it’s as bad as you say it may not be a good idea, you could consider having a manufacturing approval on the drawings.
One of the first drawings I ever did, the machinist and prototype shop fitter called me down to the floor to ask me a bunch of questions about it. Now they definitely had some valid points/questions/concerns. However, they’d also missed things that were on the drawing, several times I pointed out that what they were asking me was there etc. My point being, typically there’s give and take on both sides, if the pendulum swings too far either way you’re in trouble.
In the USSR for instance, the design engineers were apparently only involved up to the prototype stage. Once ready for initial production the design was handed over to the separate manufacturing facility and they’d basically make any changes they wanted to suit manufacturing. This sometimes resulted in significant quality/performance issues. (Not sure how true this is or when but I saw it on a documentary about either the space race or some aircraft development, I can’t remember which.)
While sometimes the case, just because he doesn’t have a degree doesn’t automatically mean he doesn’t know what he’s on about. I’ve known shop floor folks that had more sense than chartered (UK version of professional) engineers.
KENAT,
Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:
What is Engineering anyway: faq1088-1484