Re: [rp-ml] Design for (Rapid) Manufacturing

Dear All,
my feeling is one critical issue to let RM become a real industrial way
of manufacturing.
I fully agree that it is necessary to let industry (but not only, for
example arts) know more about the possibilities of manufacturing, of
integration of functions, etc...
This is a way of applying DFM approach with the possibilities and
constraints of RM technologies and processes (direct and undirect).
Actuall we are on the way of propositing a method for choosing the
technologies depending on the needs of the designers. We did the same
job for rapid prototyping at the end of 90s when we proposed an expert
system for the choice of rapid prototyping processes depending on the
definition of particular RP requirements.
But, now, we can consider that this is a "chicken and egg" problem. The
design has to be adapted to the technologies and the processes and we
need to have to simple butt efficient way of analysing th epossible
routes using RM technologies to achieve the parts in economical and
industrial contexts, but we also need to let the technologies and the
processes change in order to have some crucial efficient, robust and
repetible characteristics in order to be integrated in some "good
practices" guide that let the designer be sure and confident about the
manufacturing results.
Some standards are also under discussion and the existence of standards
is also a part of the answer because the standards will figure out
charateristics and good practices that could be used by the designers.
William propose some interesting summary about the influence factors and
choice factors, and also some "envelop process planning" as a tpical
manufacturing route for a RM part. These are interesting contributions
to Design for RM.
I hope that we, in Nantes, will be able to contribute with some inputs
in a paper submitted to the RPJ in a new future.
All the Best,
Alain

William Watson a écrit :
>
> RP-ML:
>
>
>
> I was recently asked by our local IDSA chapter to write a short note
> on designing for rapid manufacturing processes. Although there is a
> lot of documentation on design constraints for other manufacturing
> processes (injection molding, sand casting, et al.), there is little
> help for designers in the additive fabrication space.
>
>
>
> I thought I would open this conversation up to the RP community with
> the hope of finding more help for the designers looking for better
> prototyping guidance as well as developing support for accepted DDM
> constraints.
>
>
>
> The article below was written for the industrial designer with little
> or no experience with rapid manufacturing. Obviously there is much
> more detail and depth than I covered. Hopefully this is a good place
> to start.
>
>
>
> The original can be found at:
> http://www.idsacarolina.org/2/post/2009/03/design-for-rapid-manufacturing.html
> <http://www.idsacarolina.org/2/post/2009/03/design-for-rapid-manufacturing.html>
> Here is the text:
>
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> Design for (Rapid) Manufacturing
>
>
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> Rapid Prototyping (RP), Additive Fabrication, Direct Digital
> Manufacturing, 3D Printing are just four of the many different ways to
> describe the twenty-two -year old industry based on technologies that
> build parts up, layer by layer. For the designers new to the
> technology, the promise is the same:
>
>
>
> Everything drawn in 3D CAD can be sent to a 3D Printer.
>
>
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> If only product design was that easy. When your design process
> involves rapid prototyping, knowing about the materials and process
> can improve the outcome of your prototype.
>
>
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> There are two equally false thoughts about prototyping materials:
>
>
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> • RP parts are super fragile and super expensive – DON’T DROP THE
> PROTOTYPE!
>
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> • RP materials come from “unobtainium” and are a perfect match for
> all designs and assemblies
>
>
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> Although the first notion was probably true ten years ago, things have
> improved dramatically. Materials are stronger and better mimic the
> engineering polymers intended for production parts. Also, lower cost
> processes have reduced the overhead of many suppliers. For many
> processes, ordering a second piece only adds a fraction of the cost of
> the first. Since your marketing manager is going to keep the first
> model, might as well order two so you have one to use to communicate
> with engineering and manufacturing.
>
>
>
> Of course, the thought that RP machines can make everything is equally
> false. If your design includes sheet metal, expect to make some
> thickness changes before sending the STL file to the model shop. Many
> assemblies incorporate multiple materials to optimize the design for
> strength or weight. Do not expect one RP material to cover that very
> wide range of material properties.
>
>
>
> So, what is a designer to do? First, think about your design and
> product development goals. Then pick a prototyping strategy that best
> meets those goals.
>
>
>
> General design considerations:
>
>
>
> • When Outsourcing
>
> - Match your design with the right process
>
> • Small medical device? SLA
>
> • Color concept model? Z Corp
>
> • Over molded plastic/rubber? Objet
>
> - Be realistic about lead times
>
> • Start to finish with shipping time, outsourcing takes a week
>
> • Give your supplier a heads up when projects are on the way
>
> - Understand cost and time drivers
>
> • Material Volume
>
> • Build Envelope
>
> • Post Processing
>
> • In House 3D Printing
>
> - Know the strengths and limits of your process
>
> • Modify the design to make post processing easier
>
> • Know when to use assemblies, and when to manually assemble
> components
>
> • Use hollow or sparse builds to minimize costs
>
> - Understand support materials and post processing
>
> - Determine how to make the build more efficient. What drives time?
>
>
>
> Just like most other manufacturing processes, RP appreciates good
> design. Simple rules like constant or similar wall thicknesses help
> make growing and processing the parts much more efficient.
> Cantilevered beams often need support, and sheet metal features need
> to be thickened. Most importantly, using good design sense and
> understanding how your parts are made will help you make better
> designs in less time with less money
>
>
>
> Bill Watson, IDSA is the managing partner of Anvil Prototype & Design
> ( www.AnvilPrototype.com <http://www.anvilprototype.com/> ), a Z
> Corporation partner and RP service bureau based in Charlotte, NC.
>
>
>
> Bill Watson
>
> Anvil Prototype & Design
> www.AnvilPrototype.com <http://www.anvilprototype.com/>
>
> 4101 Stuart Andrew Blvd. Suite F
>
> Charlotte, NC 28217
>
>
>
> Bill.Watson@AnvilPrototype.com <mailto:Bill.Watson@AnvilPrototype.com>
>
> Voice: 704-527-8171
>
>
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