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Prototyping

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eliou

eliou

Mechanical
Nov 23, 2006
41
CA
Hey guys,

I was wondering how a machine shop usually charges you if you want to prototype something. I constructed the 3D model in catia so hopefully it can be translated to work in most cnc machine. So here are the questions:

1) Does the complexity of the features drive up cost in cnc machining?

2) If a part is relatively simple, would it be cheaper to have it machined manually? Or is cnc usually cheaper?
 
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There is no stock answer.

Let's start with material. Is it aluminum, steel, cast iron or is it 17-4 stainless, Inconel, tool steel, or whisker reinforced composite aluminum? Cost of material and machinability will impact the cost.

Tolerance is the next area. Is the part +/-.010", +/-.001" or +/-.0001" in tolerance. Tighter tolerance generally increase cost.

Features such as a threaded shaft with 1"-8 V-thread, or 1" Acme thread or 1" Buttress thread impact the cost.

Finish can also impact the cost.

Have the part quoted and take the best price and hope you got a reputable shop.
 
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eliou,

There are many things which when drive the price, turn around time, qty, tolerances of the part, coatings, surface finishes, number of features and types of features, material etc....

Best thing to do is design the part for manufacturability. If you have a part which you are not sure if it manufacturable or not, then perhaps it is easiest to send the part off to a couple of vendors and gather feedback from them.

We are a prototype shop and we give constant feedback to our customers and ways to improve the design to minimize cost.

In regards to CNC versus manual..

Manual is fine for an extremly simple part... plate with holes drilled in it...

However if you have a part that has numerous features and that has the possibility for growing into larger qty's then 1 then your best to find a cnc shop.

Good luck!
 
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Prototypes can be a viable option prior to releasing for production. Size, complexity, and material are all factors in determining cost.

A couple of options are:
1) Smaller scale model of part you want
2) Aluminum or plastic material for prototype


Tim
 
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Thanks for all the help guys. The part that I am trying to make is about the size of a wallet. It has a few holes (non threaded), a few fillets, and the tolerance has to be within a millimeter. The feature count is pretty low. I know its impossible to tell me the cost right from that, but would anyone be able to give the the price range that im looking at? would it be around $10? 20? 100? 500? I've just never had anything machined before so I am completely clueless.

Thanks again for the great help guys!
 
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Can you put the drawing in a Word file and post it somewhere for us to view? List a material and a quantity, and I'm sure a few of us on here could post a ballpark estimate to give you an idea of what to expect.

If you're under 10 parts, the material is garbage steel (A2, D2, 4140, or equiv.), and there aren't too many holes, you're probably going to pay between $30-$60 per part. 10-20 is likely negotiable, and over 20 parts will probably see a discount. That's based on a shop rate of ~$50 per hour. Small shops I've worked with in PA, WI, IL, etc., seem to run a standard rate of $50-$65 per hour depending upon part size/complexity, equipment required, and the amount of engineering/programming required.

If you want the dimensions certified on an inspection report, add another $10-$15 or so to the per piece price. Use a company with ISO certification and it'll cost you more. A backyard shop will probably be a heck of a lot cheaper.

Hope that helps and isn't misleading.



 
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Hi, I will post it soon. I am currently away from home and do not have access to my catia models. Thanks for all the great help guys.
 
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yeah, there might be modifications to this part, but that's basically it. Very low feature count and nothing complicated. So I'd assume it would be very inexpensive to make this part?
 
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That part is a little more complicated than you might think, at least that's the case when you put in all of those square corners (and if I'm reading the model correctly). Those corners in the top of the part will require an EDM machine to pick them out to give you the 90 degree angles. The same can be said for that small pocket on the bottom side. This looks like a hinge of some sort???

Ballpark that one piece at about $515 assuming you want the corners squared, the part remains mild steel, and your geometric tolerances aren't out of sight. That's doing it partially manually, and partially with CNC (bottom-side pocket and radius portions of the part). Each additional part should drop the cost somewhat. If you can live with internal radii in the corners, the piece price will drop alot more. Heat treating the part is going to allow for warp, so if you have heat treatment and flatness specs to hold, the price will likely go up.

Definitely get this one quoted. If cost is an issue, you'll need to discuss with an individual shop what you can do to drop the per piece cost.

And let me know if I'm way off. I'm more familiar with tool & die making wages, so I'd be curious to see what a general machine shop charges. Also lets me know if this was useful at all.

 
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I used to work as a project manager at a DoD manufacturer. For what it's worth, I agree with TripleZ's assessment. If it were mild steel and "typical" tolerancing, etc - I'd quote it out at around 300$ for a single part run.

I'd recommend at least a R.25 wherever you can fit it in and still meet your requirements.

It's also going to be a little hard to hold onto. Could you have this part be made out of a RP plastic instead?

 
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Yes, plastic could be an option. Would there be a significant price drop if it were made in plastic and the 90 degree angles eliminated?
 
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Try sending the geometry - as you have it now - to a rapid prototype shop - somewhere like Red Eye or whomever else shows up on a Google search. You should be able to get an instant quote. Also, they will have information about material prop's that you may be interested in.

On the radii - it would reduce cost on a machined product... Remember, most tools are round. While this isn't always true - ie: edm, etc - it's a good thing to keep in mind.

Also, if there's a shop in your area... see if you can send prints out for quote and then arrange to stop by and see if they can't give you a bit of advice on design for manufacture...

Best of luck.
 
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Sorry, I made an assumption.

We usually do a prototype for function before we do a final prototype for the many excellent reasons given.

A functional prototype saves us time and money and usually points out things we didn’t consider originally.

tom


Thomas J. Walz
Carbide Processors, Inc.
 
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