Design for Manufacturability & Assembly at low production volumes 2

[KENAT]

We had 3 days of DFM/A training last week and frankly I was a bit underwhelmed.

1st off in terms of actual things to do or not do I didn't learn much I didn't already know. There were a few things but nothing outstanding.

2nd it seemed tailored to much higher volumes than we deal with. Don't get me wrong, I'm not saying DFM/A should be ignored for lower volumes but it seems that a lot of the trite truisms that get spouted are less applicable. Also the time spent on the DFM/A analysis is a lot more significant amortized across a few dozen parts compared to hundreds of thousands.

However, manufacturing engineering management claim they are serious about it so I figured I'll pretend to drink the kool aid and go along with it.

So, in that vain vein, can anyone point me to any resources that really address DFMA/Concurrent Engineering/DFX or whatever you choose to call it for low volume production? I did searches on here & Google for many of those terms bud didn't turn up much.

To give you some idea of volumes, our highest would be somewhere under 300 units per year for one of our electrical control boxes that get used on multiple product lines. Our more popular actual microscopes sell perhaps 75-150 per year. Our less popular ones perhaps less than 40. Our really big automated systems and various accessories may sell 5-15 a year and we also do 'specials' which can be one offs. Product life is typically under 10 years so even our highest volume control boxes would be lucky to hit total production much more than a couple of thousand.

Thanks for any help.

(I know this should probably go in "Industrial/Mfg engineering other topics" but that forum doesn't get much traffic so I thought I'd stand a better chance here.)

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[jmw]

Seems like, if its anything like some companies I know, the presenter probably didn't prepare the material, it is a standard presentation prepared by someone who knows/knew and once cared.
It was probably written for companies with much bigger production runs. Marketing now "owns" the presentation.
They are now prospecting further down the pyramid.

He also didn't do any research or ask any questions of management.
No one should expect management to know what is or is not relevant and in this case probably justifiably.
What the sales company ought to have done is asked some sensible questions and adapted the presentation.
But in all probability some one spoke to management, handed out all the usual "30% better gas mileage" claims, got enough interest to get the manager to agree to a presentation and then shut down the conversation before he could change his mind.
He then delegates down the tree (of course, being told that he can do what the big boys do is always an attractive lure. It now depends on how long the boss remains hooked after the conversation has ended.)
Then the the sales company just tasked whoever covered the territory to come and give the presentation.
He probably didn't do any/much research either.

I hate these things management say yes to.
Usually the seller starts the dialogue at the top with a senior manager to senior manager chin wag.
Then your senior manager downloads the task to your boss who either attends or delgates attendance to some one else.

I hate it when I am that someone else because there is usually some agenda I don't know about between my boss and his boss and I am the agreed sacrifice.
I then have to:
(a) see if it has any legs
(b) work out which boss wants to be told it has legs or it doesn't have legs whatever the real state of affairs is and then work out my best survival plan, especially if the bosses have different expectations.
My best survival path is if both bosses agree on what they expect and the proposal meets that expectation and I can recognise it.
This is really where you would want to see one of the brown nosers tasked but they have better defences than most of us.

My best survival plan usually involves trying to appear interested and enthusiastic but denying any purchasing authority (they should have figured out that management usually don't attend because they do have purchasing authority and don't want to be tricked into using it by some smart alec salesman).
I tried not to indulge in "career limiting" questions/comments etc... not that that did me any good.

JMW

http://www.ViscoAnalyser.com

 

[KENAT]

I think he was a one man consultancy, but can't recall for sure.

At least some of the material was pulled from books on DFMA, six sigma etc. I know this because I was flicking through the six sigma book I have looking at the dfma section and some of the illustrations looked very familiar!

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[KENAT]

May have found something from Greg's alma mater:

http://www-edc.eng.cam.ac.uk/books/designingforlowvolume/

Another one from back home across the pond:

http://www.thamesandhudson.com/9780500289181.html

(or on Amazon

http://www.amazon.com/Prototyping-L...182/ref=sr_1_1?ie=UTF8&qid=1330057857&sr=8-1)

I got these searching for 'low volume production' and 'design for low volume production'. Any native - 'Americans' am I using the wrong term to find US results?

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[jmw]

You'd expect a one man consultancy to do better than that.

JMW

http://www.ViscoAnalyser.com

 

[HDS]

Sorry I don't have any specific suggestions. I was just thinking what industry would combine the need to care about DFMA and low volume.

As other have said simply have a well defined set of preferred internal and external processes is the starting point. Then it all gets down to communications between design and the guys down the line in manufacturing. One thing that low volume usually means is that you can not sacrifice service for assembly (easy to assembly but hard to take apart). It also does require knowledge of the processes used to make the parts so they will come out right. Reuse and flexible designs become very important as they allow low volumes to ad up.

 

[btrueblood]

"the Manufacturing director basically said well now you design folk have been trained we won't need manufacturing engineering to do the analysis or even to do the analysis etc. "

Sigh. BTDT. We did a major redesign of some sheet metal weldments, incorporating "self tooling features", i.e. tabs and slots, and alignment dowel pin holes. All without involvement from the weld shop; who found the extra holes a pain, as they routinely ended up leaking and needing repairs.

Search terms sound right, Kenat. Maybe "low-rate" production?

 

[KENAT]

Nope, sadly 'Low Rate' gets lots of new articles etc. relating to 'Low Rate Initial Production' on DoD contracts etc.

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[btrueblood]

Ugh. Yeah, sorry, Kenat, shoulda remembered where I heard the term before.

 

[pierdesign]

It's an excellent topic, I too have gone through the DFMA mantra from executroids at numerous companies I've consulted at. The phenomena really seemed to take hold as a clumsy by-product of 3D CAD: otherwise skilled designers that just hadn't built obscure, complicated assemblies, ended up creating stupid assembly nightmares.

Same experiences as mentioned, BoothroydDewhurst flacks, software installed, used maybe a few times then forgotten. At several companies the only leftover exercise was an MTBF spreadsheet.

At numerous companies the common, workable solution was unanimous: in place of analysis a thorough, repeated design review process including smart manufacturing engineers whose recommendations are both required and actually enacted.

Other's have mentioned many good tips. I used the mantra of tool access with my designers including requiring some actual mockups to prove accessability, often with cruel surprises.

Specifying torque values on most fasteners ended up being one of the best rules. Ensuring proper hardware depending on accessability and chance of disassembly: thread cutting vs. rolling vs. screws into inserts or nuts.

Working out service routes very early on - cables, pneumatics, etc. - and constantly checking with their owners on suitability of routing and mounting and being very specific. This trick did discover that indeed certain cable or tube required rerouting when forced discussion on the specifics.

Being aware of load paths, especially on electrical assemblies as E-engineers have no concept and often end up with massive cantilevered loads.

 

[drawoh]

...

Same experiences as mentioned, BoothroydDewhurst flacks, software installed, used maybe a few times then forgotten. At several companies the only leftover exercise was an MTBF spreadsheet.

...

What does the software actually do?

I am working with people who are rigidly process driven. If you installed the software, they would operate it, and refer to the resulting process as DFMA. Does the software generate improved manufacturability, or does it just generate a report that we are supposed to think about?

JHG

 

[pierdesign]

Like KENAT I wasn't enthused, and after a little bit I was zzzzzz.

The best I remember a report is generated itemizing number of unique assembly steps and time to complete. You can run what if analyses. I seem to remember parallels with FEA: analyze a bracket and you can get good results, analyze entire assmebly and results are more difficult and less conclusive, unless you have a specific target.

My information is old.