RE: rp definition

From: Brock Hinzmann (
Date: Sat Feb 03 2001 - 02:31:01 EET

The purpose of defining something will alter the definition you choose to

>From a practical point of view, Jeff's broader definition is good. Rapid
should be that which is relatively more rapid than the alternatives, for
the given application. Prototyping should create a prototype that fits the
definition of a prototype for the end user, which much of what we consider
on the RP-ML to be prototyping is not.

>From a market research point of view, Terry has to narrow the definition
down to something he can get his arms around. Furthermore, from a
consulting point of view, he must be able to point out what is new and what is
changing and what his clients should do about it. Which isn't to say that
nothing new is happening in CNC machining, but most people know what they can
do with it (sic). What is different is the appearance of new methods for
realizing arbitrary physical objects directly from virtual objects (CAD).

For many years, people in this forum have argued that neither rapid nor
prototyping are sufficient to describe the new machines (to Sheba's point),
but they agreed on a term for the sake of continuing discussion and
sharing of information. Perhaps that was a mistake. I am beginning to hear
complaints that corporate managers use the technology to shorten the time for
producing a model/prototype, but have failed to use it optimize the design
of their products by realizing, in the same amount of time, a larger
number of variations on the objects envisioned by creative people working in
CAD. They can see and measure whether they are getting more rapid
prototyping than they were previously, but they are not necessarily getting better
products, however you define >>better<<.

Perhaps the name and definition are partly to blame.

Brock Hinzmann
Technology Navigator
SRI Consulting Business Intelligence

Jeff Katz wrote:
>What's wrong with using CNC machining to do "Rapid Prototyping?" In
>cases, depending on material and finish level, CNC machining is actually
>more "rapid" then RP. If the question is how do you rapidly produce
>directly from 3D CAD data, CNC should logically be included in the
>classification, otherwise it's an arbitrary distinction.
>We lump CNC and EDM in with all the others in our Rapid Manufacturing
>marketplace. If you really want to distinguish SLA, SLS, FDM, etc.
>CNC, you really need to change the name from Rapid Prototyping to
>Prototyping or even Fabbing. Right, Marshall?
>Jeff Katz
>773.477.7374 x203
>Fast, Free, Secure
>-----Original Message-----
>Message text written by Elaine Hunt
>>The Rapid Prototyping Report in 1992 defined RP as
>The Fabrication of a physical, three dimensional part of arbitrary shape
>directly from a numerical description (typically a CAD model) by a
>highly automated and totally flexible process.
>Does this definition define what you do with rapid prototyping? Should
>be expanded and if so how would you change it?<
>I've been using the following to briefly define/describe RP:
>Rapid prototyping (RP) is a relatively new class of technology used for
>building physical models and prototype parts from 3D computer-aided
>(CAD) data. Unlike CNC machines tools, which are subtractive in nature,
>systems join together liquid, powder and sheet materials to form complex
>parts. Layer by layer, RP machines fabricate plastic, wood, ceramic,
>metal objects based on thin horizontal cross sections taken from a

>Terry Wohlers
>Wohlers Associates, Inc.
>OakRidge Business Park
>1511 River Oak Drive
>Fort Collins, Colorado 80525 USA
>Fax 970-225-2027

For more information about the rp-ml, see

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