Marshall,
It might be worth looking at a paper that we published at the Rapid
Tooling & Manufacturing conference in Denmark last year. - "The accuracy
of RP models for Investment Casting of Injection mould Tool Inserts",
Heather Almond et. al.
I give a few results of accuracy tests:
Sanders
epsilon 90 = 0.35mm, 39% of error values within +/- 0.1mm, max deviation
= 0.7mm
Actua No.1
epsilon 90 = 1.0mm, 38% of error values within +/- 0.1mm, max deviation
= 1.6 mm
Actua No.2
epsilon 90 = 1.2mm, 26% of error values within +/- 0.1mm, max deviation
= 1.7mm
SLA QuickCast 1.1 No.1
epsilon 90 = 0.05mm, 82% of error values within +/- 0.1mm, max deviation
= 1.1mm
SLA QuickCast 1.1 No.2
epsilon 90 = 0.05mm, 86% of error values within +/- 0.1mm, max deviation
= 0.02mm
SLA QuickCast 2.0 No.1
epsilon 90 = 0.2mm, 44% of error values within +/- 0.1mm, max deviation
= 0.4mm
SLA QuickCast 2.0 No.2
epsilon 90 = 0.1mm, 70% of error values within +/- 0.1mm, max deviation
= 0.3mm
Phill
Professor Phill Dickens
De Montfort University
Leicester
England
Marshall Burns wrote:
>
> Dear Dan,
>
> Okay, but it would be interesting to know what are the tolerances that
> you guys who are actually using the various machines are accustomed to
> getting from them? Some people say that an important reason for choosing an
> SLA today is that the machine is mature and gives good accuracy. How good?
> And can it be as good as Sanders?
>
> Marshall
>
> DANIEL CHARLES DAVIS wrote:
>
> > Marshall,
> >
> > That's what I get for answering before my morning coffee. Two
> > thousands......twenty thousandths.......what's a few thou between
> > friends. Sorry for any confusion caused by my brain failure.
> >
> > This thread is timely for me as I was just going over tolerances here
> > for some plastic parts. I'm sure you realize that in the auto industry,
> > especially Asia, our tooling is held to 0.1-0.2mm (or even looser) for
> > 90+% of what we make. That leads me to wonder: how many consumer
> > product industries REALLY need to hold accuracy to 0.05mm overall? Of
> > course that can get us into a whole debate regarding engineering
> > practices ala Taguchi methods and "robustness." This is the wrong forum
> > for that although I would be happy to discuss in private.
> >
> > Regards,
> > Dan Davis
> > Head, RP&M Division
> > PROTON Berhad
> > Hicom Industrial Estate
> > Batu Tiga, PO Box 7100
> > Shah Alam, 40918 Selangor MALAYSIA
> > +60 3 515-2380
> >
> > > ----------
> > > From: Marshall Burns[SMTP:marshall@ennex.com]
> > > Sent: Friday, June 05, 1998 10:36 AM
> > > To: DANIEL CHARLES DAVIS
> > > Cc: 'James Theoharris'; 'RP-ML'
> > > Subject: Re: Too many SB's & a little late
> > >
> > > Dan,
> > >
> > > Would you please clarify? You seem at first to be implying that
> > > machines
> > > other than the Sanders can hold 0.002 inch tolerance. But then your
> > > data
> > > talks about holding 0.010 to 0.014 inch. Accuracy has always been a
> > > complex
> > > issue. What point are you actually making here?
> > >
> > > Marshall Burns
> > >
> > >
> > >
> > > DANIEL CHARLES DAVIS wrote:
> > >
> > > > Hmmmm, two thousandths of an inch. Are you saying that all RP
> > > equipment
> > > > except Sanders is only accurate to that or is this only the Actua?
> > > >
> > > > Of course the Actua (and Z-Corp and other concept modelers) will not
> > > > hold tooling tolerances. If we are talking about SLA & LOM, we
> > > > consistantly hold 0.25-0.35mm (0.010-0.014 inch) tolerance evben on
> > > full
> > > > envelope parts. I have many CMM printouts to support that. Maybe
> > > the
> > > > folks in question just don't know how to dial in their machines?
> > >
> > >
> > >
> > > --
> > > Marshall Burns
> > > Marshall@Ennex.com
> > >
> > > *****************************************************************
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> > > *****************************************************************
> > >
> > >
> >
> > For more information about the rp-ml, see http://ltk.hut.fi/rp-ml/
>
> --
> Marshall Burns
> Marshall@Ennex.com
>
> *****************************************************************
> ***** ENNEX(TM) CORPORATION
> ***** Fabbing the Future(TM)
> *****************************************************************
> ***** 10911 Weyburn Avenue, Suite 332, Los Angeles, U.S.A. 90024
> ***** Phone: +1 (310) 824-8700. Fax: +1 (310) 824-5185
> ***** E-mail: Fabbers@Ennex.com. Web site: http://www.Ennex.com
> *****************************************************************
>
> For more information about the rp-ml, see http://ltk.hut.fi/rp-ml/
For more information about the rp-ml, see http://ltk.hut.fi/rp-ml/
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