Prof. Bernard & Catherine,
Below is a short summary of a presentation I use at seminars/trade fairs
in Asia for marketing the Proton Rapid Prototyping & Manufacturing
Centre (RPMC). I have left out any explanation of the RP processes as
everyone on this list should know what they are.
None of this is "rocket science," but commercial use of this text is not
authorized without my permission.
*********
INTRODUCTION
The Proton RPMC can make both rapid prototype (RP) patterns and
short-run production-intent prototype parts. How do we choose the
methodology and processes for the development of each?
RP PATTERNS
Before one can make an informed decision regarding RP, one must know the
speed and limitations of traditional manufacturing processes as well as
the capabilities of the RP processes. This experience cannot be fully
learned in school or accurately simulated in a computer program as there
are too many "gray" areas.
At the Proton RPMC, we have three choices for the manufacturing of
prototype patterns: SLA, LOM & hi-speed CNC (which I consider an RP
process). We use a high level decision criteria that includes, in order
of importance: a) final use of pattern, b) part geometry, c) scheduling
and d) cost. You may notice we leave out accuracy. This is because the
RPMC can achieve the same standard overall accuracy (~0.2mm) regardless
of the process used. If a special (tighter) tolerance is required that
need can be assessed further, but it is not the normal course of action.
When considering a) the final use, one must know the durability of each
pattern (e.g., number of shots a DirectAIM tool can accept) and the
expected lifetime of the pattern (i.e., how long the pattern will be
dimensionally stable).
Assessing geometric considerations (b) requires the knowledge of RP
material strength and RP machine manufacturing limitations -- sometimes
machining is a better way to go. It is also related to d) cost (e.g.,
LOM or CNC are better to build large solids vs. SLA due to material
expense).
Scheduling (c) matches the needs of the customer with the speed and
availability of the machine, which also directly relates to d) cost.
The costing and speed even some geometric considerations can be answered
using a build time estimator and equations to determine the material
usage. Naturally, as one gains experiencethe dependence upon these
tools lessens (i.e., I can look at a part and determine the optimum
machine to use, but some of my staff yet cannot).
PRODUCTION-INTENT PROTOTYPE PARTS
As far as prototype manufacturing processes go, one has to consider both
plastic parts and metal parts.
At the Proton RPMC, plastic prototypes can be made in one of two ways:
using soft tooling or short run production-like tools. Considering a)
customer requirements, b) delivery time and c) cost (once again in order
of importance) allows the RPMC to make the assessment.
RPMC customer requirements are generally comprised of material
specifications and build methods. As a standard operating procedure, we
try to go the route of vacuum casting with polyurethane (PUR) and RTV
silicone molds, as this is the fastest and lowest cost option. There
are many, many PURs on the market that are engineered to simulate a
multitude of thermo-plastics. However, the RPMC must work closely with
the test engineer and materials engineer (often the same person) to
determine whether the PUR part will work for the intended product
life-cycle testing. Also to consider is the build method, which refers
to whether the part is a homogeneous or a layer laminated part. For
most testing, an ABS part from an FDM or a nylon part from an SLS cannot
be used as the mechanical properties are not the same as for a
homogeneously built part.
If the PUR material is deemed unacceptable, the RPMC then turns to short
run production-like tools such as Al & "soft" steel, epoxy, spray metal
or DirectAIM. The decision of which of these methodologies to use is
based upon a) the required lead time, b) number of parts required and
c)cost.
The Proton RPMC creates metal parts either directly (e.g., QuickCast,
DSPC or TekCast) or indirectly (e.g., sand cast tools built on the LOM
or CNC). The decision criteria are a) geometric complexity, b) number
of parts required and c) cost.
*******
I hope that this helps. Cheers.
--- Regards, Dan Davis PROTON Rapid Prototyping & Manufacturing Center Hicom Industrial Estate Batu Tiga, PO Box 7100 Shah Alam, 40918 Selangor MALAYSIA +60 3 515-2380 phone/fax> -----Original Message----- > From: Catherine Minich [SMTP:cminich@astro.ocis.temple.edu] > Sent: Wednesday, September 23, 1998 9:46 AM > To: Alain BERNARD > Cc: rp-ml@bart.lpt.fi > Subject: Re: comparison between RP processes > > I, too, would be interested in this information. If you intend to > respond > privately, please include me in your response. > > Thank-you, > Catherine Minich > Tyler School of Art > Metals/Jewellry/CAD-CAM > > On Tue, 22 Sep 1998, Alain BERNARD wrote: > > > Dear RP collegues, > > > > One of my students is doing a study on the comparison between RP > processes > > in order to be able to choose how to produce some functional parts. > > What are the criteria and the associate processes to go from product > > specification or from CAD files to part manufacturing (plastic or > metallic)? > > Have you seen such study recently ? > > > > Looking forward to reading you, > > > > Best Regards, > > > > Prof. A. BERNARD > > > ---------------------------------------------------------------------- > -- > > Prof. Alain BERNARD Tel : + 33 (0)3 83 > 91 27 29 > > Professeur des Universites + 33 (0)3 83 > 91 20 09 > > CRAN ESA CNRS 7039 Fax : + 33 (0)3 83 > 91 23 90 > > UHP Nancy I - ESIAL > > BP n° 239, 54506 - VANDOEUVRE Cedex - FRANCE > > ATTENTION ! NEW E-MAIL ! > > e-mail : alain.bernard@cran.u-nancy.fr > http://www.cran.u-nancy.fr > > > ---------------------------------------------------------------------- > -- > > > > 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/
For more information about the rp-ml, see http://ltk.hut.fi/rp-ml/
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