Re: Applications
From:
Ian Gibson (University of Hong Kong)
Date:
Friday, March 17, 1995
From: Ian Gibson (University of Hong Kong)
To: RP-ML
Date: Friday, March 17, 1995
Subject: Re: Applications
>this lull I would like to probe for some insights from this group.
I agree there does seem to be somewhat of a lull in proceedings, where is
everyone?
> - Concept Models
> - look, feel, show to client
> - Design Verification
> - form and fit
I have no problem with the above although I do believe that there should be some mention of the words parallelism and iteration, I said iteration (bad
joke). Part of the difficulty in explaining the technology to those
uninformed and sceptical industrialists that remain out there revolves
around the philosophical changes to company structure affected by RP. What
I mean is that you are providing a tool that does not just replace another
tool, it can allow designers and developers the flexibility to evaluate a
variety of designs beyond the concept stage in much more depth than
previously possible for anyone other than the big budget designers.
> - Testable Parts
> - form, fit and some function
Here I am starting to have problems. What is a testable part? Just how
close are the test results to the real thing? Perhaps we should split this
category into 2 separate areas, one that shows an accurate representation
of test data, the other that shows a correlative representation of test
data. In other words the ABS from FDM machines can be used to represent an
accurate ABS part in terms of thermal behaviour but would not give accurate
drop test results due to interfacial separation of plastic beads. However a
positive drop test result would mean that the true ABS part is going to be
more than satisfactory.
> - Patterns for "Soft" Tooling
> - RTV, spray metal, etc.
> - Patterns for Metal Casting
> - investment, sand, flask, etc.
> - Hard Tooling for Manufacturing
Here we must also be honest. This is RP as part of a manufacturing process.
In other words, in conjunction with other machine based processes. Doug Van
Putte at Kodak described using Quickcast parts which were then
milled, surface ground and wire EDMed. I dont dispute that RP is a valid
part of this chain, but it does give me problems in terms of distinguishing
the above two (or perhaps three since RTV mouldings, etc. can be used
to master wax patterns) categories. What are these patterns going to be
used for? Can we really make parts that dont require further machining? Id
like to hear about it.
>Are there better ways to segregate these? What is missing?
Missing? What about parts that would be extremely difficult or impossible
to build using other approaches? What about the mechanisms that dont
require assembly, or the direct translation of CAT scans? They kind of fit
into the above categories but may also represent subcategories.
The reason I mention this is twofold. People have been ranting on about
conservative attitudes and then directed their attention at unimportant
issues like names. My view is that the conservatives amongst us are
ignoring the fact that microfabrication (or nanotechnology, or LIGA, or
????, you think we have difficulties with names?) techniques have been
around for some time. Okay some say that RP is time saving, but surely its
real benefit is that it is geometrically independent? The same can be said
about microfabrication. Eventually someone will come up with a MF system
with a direct CAD input that allows you to make items that could never have
been dreamed of before.
Secondly, when are we going to stop thinking in layers? We design
parametric CAD systems that allow us to think in terms of features and
characteristics and then we constrain the output to build the parts in
layers. Surely there must be something fundamentaly wrong in the
mechanics of this approach? Shouldnt we be looking at building
parts in an omnidirectional way? Crystals grow from a central seed. People
can steer the growth of crystals to build simple structures like turbine
blades. When are we going to see an RP system that builds in the same way?
I feel better for that.
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