Considerations for Manufacturabality. 2

[Madhu454]

Hi All,
I dont know this question may not be relavent for this forum. But I hope still I can get some good feedback.
Can anybody share best practices are considerations that we need to make while designing the parts with respect to Manufacturabality. I dont have much knowledge on the Manufacturing. Any basic things we need to consider while desiging or dimensioning the parts. can somebody provide a link/source for this learing.

Thank you.

 

[CheckerHater]

You can start here:
[URL unfurl="true"]http://www.omwcorp.com/partdesign.html[/url]
Then you slowly work your way towards something like this:
[URL unfurl="true"]http://www.amazon.com/gp/search?index=books&linkCode=qs&keywords=007007139X[/url]
Unfortunately, no book, no matter how thick, will be enough.
Try to get in touch with people who will produce parts you design. Try to learn more about manufacturing, on your own pace or by taking the class.
One thing for certain: your enlightenment will not happen overnight.
Good luck!

 

[DanStro]

I've found that the absolute best thing is to talk to machinists, preferably the one(s) that will be making your parts. This way the feedback you get will also be based on their specific abilities and not just general statements.

HTH,
Dan

Han primo incensus

 

[TheTick]

There is no short cut. Get out of your chair. Get out and learn the processes. Talk to the people.

Don't forget to talk to the people in the quality department. They can provide insight into process capabiilities. This is most important when deciding how to add tolerances.

Without process knowledge, your drawings are little more than bad art.

 

[dingy2]

Right on Tick. I don't know how many drawings that I have seen over the years that are highly improbable to manufacture or features that are more than difficult to confirm. Even on this forum, some participants feel that manufacturablity or improbable to confirm should not be taken into consideration. I just hope that companies have both design review and design failure mode and effects analysis programs in their company which would sort out many of the problems prior to the drawing being released.

Dave D.

http://www.qmsi.ca

 

[drawoh]

Madhu454,

Product Design for Manufacture and Assembly by Boothroyd, Dewhurst and Knight.

Other than that, I agree strongly with the above suggestions to talk to your fabricators.

JHG

 

[KENAT]

What processes are you interested in, which will in turn be determined by your industry, volume etc.

Talking to people may be the best option but that doesn't mean you take everything any machinist tells you etc. without a pinch of salt.

The capabilities of machinists & their tools etc. varies.

We have one shop that can do ridiculously tight stuff day in, day out without too much complaining. Trouble is if you design for their capabilities, rather than to what is functionally required, you end up with overly tight tolerances such that you can't just send the part to 'any competent machine shop'. We live this problem - used to be most drawings were designed to their capabilities and invoked +-.002 all over the place. When they got busy, if we tried sending the parts elsewhere we had trouble getting good parts.

On the other side, some machinists/shops will mess up or not see the wood for the trees etc. so sometimes though they'll say it can't be done, another shop will be fine with it.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[ewh]

some participants feel that manufacturablity or improbable to confirm should not be taken into consideration

A strong statement, examples of which I am happy to say I have seen very few. Such an attitude generally leads to short assignment durations unless someone else is covering for the designer. More often the disagreements center on which takes precedence, not that they should not even be taken into consideration at all.
On the other hand, I have seen discussions among engineering, manufacturing and quality departments where the necessity of certain designs is closely examined due to such issues. Most often more acceptable means are agreed upon and lessons are learned, but there are occasions where, due to a variety if issues, a complex design requires that extra effort and cooperation between those involved in order to meet product expectation is the order of the day, as well as the usually considerable extra expense involved.


“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV

 

[geesamand]

In my industry, our designs are produced is medium-low volumes. So the vast majority of our parts are built for fabrication / machining or casting / machining.

GD&T is valuable *if* you have some understanding of how the piece will be machined and inspected. I aim to make a GD&T strategy for the part that can be implemented in the manufacturing, the vendor's inspection department, our own inspection department, and last but not least, the functional design intent.

Every part tends to be different, every shop or group of vendors is different, every inspection department is different. If you want the lowest cost with the shortest lead time with the highest quality, you have to find a design that bridges all of that.

For longer-lead time designs produced in higher volumes, or where quality is more rigorous than cost, you may find you can impose further on the supply chain as the size of the orders will justify job-specific tooling and fixtures.

This is a big subject and manufacturing has it's own language. These individuals have a lot to teach even though they may have no idea that they're speaking greek to you. They don't teach terms like "chuck", "steady-rest", "centerless ground", or "indicate" in engineering school, so the best thing to do it get out and see the parts being made and see what these things are with your own eyes. It also helps to find the person(s) in your company who understand manufacturing relatively well and ask them how they think a particular part will be made.

David

 

[powerhound]

I agree with most of what you said except for your paragraph on the value of GD&T. GD&T is valuable even if you don't know how a part will be manufactured. In my opinion, design intent should be the first consideration, inspection second, and manufacturing last. I'm a machinist but I'm not one to try to bend design and engineering to meet my own ends. If you are applying GD&T based on manufacturing first you are completely defeating its purpose.

Powerhound, GDTP S-0731
Engineering Technician
Inventor 2010
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II

 

[ptruitt]

Good comments!

When you hear "manufacturability" study "process capability". When people say that the design is process-capable and the parts passed inspection, ask them what measurement uncertainty value was used.

Peter Truitt
Minnesota

 

[fcsuper]

Don't forget to talk to the people in the quality department. They can provide insight into process capabiilities. This is most important when deciding how to add tolerances.

It depends if you have a sharp Quality Dept, or a bunch of bodies filling seats. I've seen situations where every time an Engineer visited the Quality Dept, that person would end up in a hour long session training them how to user their own equipment. lol

Matt Lorono, CSWP
Product Definition Specialist, DS SolidWorks Corp
Personal sites:
Lorono's SolidWorks Resources & SolidWorks Legion

 

[CheckerHater]

Our Quality Manager is not aware that people invented standards yet.

And fscuper, glad to see you are changing your opinion about engineers.