RE: Minimum feature sizes on RP parts

From: Anshuman Razdan (Razdan@asu.edu)
Date: Wed Jul 24 2002 - 19:49:41 EEST


Features like beauty is in the eye of the beholder. Having said that, one
way of consistently describing features is using curvature as a boundary
limiter. I would recommend looking at some papers on our site
http://3dk.asu.edu on segmentation of meshes.

AR

Dr. Anshuman Razdan
Director, PRISM
http://3dk.asu.edu
Phone: (480) 965 0483 (Tina)
Office: GWC 574
Arizona State University
Tempe AZ 85287-5906

> -----Original Message-----
> From: owner-rp-ml@rapid.lpt.fi
> [mailto:owner-rp-ml@rapid.lpt.fi] On Behalf Of Candi Majewski
> Sent: Wednesday, July 24, 2002 2:54 AM
> To: rp-ml@rapid.lpt.fi
> Subject: Re: Minimum feature sizes on RP parts
>
>
> Dear Ed and list!
>
> Thanks for all the replies so far, it has been interesting to
> see some of
> the comments people have!
>
> Many of you have questioned the exact definition of 'feature
> size', so now I
> would like to put another question to you all.
>
> What do people out there working with RP feel would be the
> most useful
> definition? Would it be the minimum wall thickness that could
> be produced,
> or would you rather know the smallest radius achievable? Or would the
> minimum possible height of a protrusion, or the minimum depth
> or width of a
> recess?
>
> Once again I am looking forward to your comments!
>
> Candi
>
> Candice Majewski
> Rapid Manufacturing Research Group
> Loughborough University
> UK LE11 3TU
> Tel: +44 (0) 1509 227564
> Fax: +44 (0) 1509 227549
> http://www.lboro.ac.uk/departments/mm/research/rapid-manufacturing/
>
>
> >From: EdGrenda@aol.com
> >To: candimajewski@hotmail.com
> >Subject: Re: Minimum feature sizes on RP parts
> >Date: Fri, 19 Jul 2002 10:29:10 EDT
> >
> >Dear Candi:
> >
> >Other folks will have better, more up to date comments, I'm sure, but
> >that's
> >never stopped me. "Feature size" is not quite the same as
> "resolution." Is
> >there an exact definition? I don't know. I suppose a lot
> depends on the
> >nature of the feature, but here goes:
> >
> >
> >
> >In a message dated 02-07-19 08:54:59 EDT, you write:
> >
> ><< Below is a list of the processes I am looking at, along with the
> >feature
> > sizes I have down at the moment.
> >
> > I am interested in any comments anyone may have - are these numbers
> > reasonable, have you successfully produced smaller features than
> >these,
> >or
> > are these sizes unrealistic?
> >
> >
> > Stereolithography - 0.1mm
> >
> >***EG: There are special systems, and special techniques that can go
> >down
> >to
> >a fraction of a mil using what we think of as "classic," moving-laser
> >stereolithography. Generally what you give up is part size. Other
> >techniques, such as those used by microTec in Germany can produce a
> >resolution in the single micron range. Quite a bit of work
> is going on at
> >the nanometer level in the MEMS area, as well. Is all this
> SL? It all uses
> >photopolymers shaped by light, so depends on your
> definition. I'd say it
> >is.
> >
> > Fused Deposition Modelling - 0.2mm
> > Direct Metal Laser Sintering (EOS) - 0.2mm
> >
> >***EG: EOS recently introduced a steel powder capable of producing 20
> >micron
> >layers. Min feature size may stay in this range though,
> depending on how
> >robust details are. Finishes are certainly improved.
> >
> > Laser Sintering (3D Systems) Metal - 0.2mm
> > Laser Sintering (3D Systems) Plastic- 0.2mm
> > Laser Sintering (3D Systems) Sand - 0.5mm
> > Wax Jet Printing - 0.2mm
> > 3-D Printing (Soligen) - 0.5mm
> > 3-D Printing (Pro-metal) - 0.2mm
> > 3-D Printing (Z-Corp) - 0.5mm
> >
> >***EG: Both starch and plaster materials produce layer
> thicknesses well
> >below
> >this number. Mostly people seem to be using plaster these
> days and I
> >believe
> >the typical layer thk is about 0.004". Looking at parts,
> I'd say the min
> >feature size might be twice that or around 0.008". Whatever
> it is, it's
> >probably better than 0.020".
> >
> > Laminated Object Manufacturer - 0.5mm
> >
> >***EG: Some of the parts made by Kira seem to be quite a bit better
> >than
> >that.
> >
> > Ink Jet Printing (Objet) - 0.05mm
> > >>
> >***EG: The existing machines produce 20 micron layers and have
> >different resolutions in the x-y directions of 300 x 600
> dpi. It would
> >seem that min feature size would have to be greater than 0.05mm.
> >Incidentally, 3D is about to introduce a copy based on their MJM
> >machines.
> >
> >
> >Please post a summary of the responses you get, or please send me an
> >email. This could be a pretty interesting subject and
> inquiring minds
> >want to know!
> >
> >Hope this helps,
> >Ed
> >
> >Ed Grenda
> >Castle Island Co.
> >19 Pondview Road
> >Arlington, MA 02474 USA
> >781-646-6280 (voice or fax)
> >EdGrenda@aol.com (email)
> >http://home.att.net/~castleisland/
>
>
>
>
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