Re: RP vs 5-axis mill

Date: Thu Jun 05 1997 - 15:59:50 EEST

Don Wilde,

In a message dated 97-06-04 17:34:36 EDT, you write:

<< A 5-axis is a pretty amazing widget, and it's good for a lot of
 things, but there are some pieces that just can't be made, even with
         As far as advantages/disadvantages, a mill is a subtractive
 device. You waste all the metal you cut. RP >> metal part systems like
 our Soligen Direct Shell Production Casting cast their parts, with all
 the advantages and disadvantages of that distinction. Another challenge
 you face is holding the work, especially for a complex-surface piece like
 a manifold.
         If you use a mill for production, you end up with tool wear
 problems which cut down the repeatability of the product's dimensions.
 Cast parts, once gated properly, are more consistent.
         Ideally, you want both, because you need to machine the mating
 surfaces to tighter tolerances than sand or investment castings can hold.

This is a thread with a lot of interesting potential - but (to me)
surprisingly few comments.
In what might be viewed as a "devil's advocate" role here, I'll speculate;

1. Compensation methods have been, and are being, developed so that in spite
of tool wear, temperature change, etc., etc. 5-axis machine precision will
remain a moving target - for RP to catch up with.

2. "Waste" is a complex issue, involving both cost of the original material
and the potential for recycling (not to mention environmental issues of
solvent washes and cutting coolants, etc.) Subtractive methods aren't always
the obvious losers here.

3. No question about workholding, work access, intricate geometry, for a
good number of items.

4. In the area of "easy art-to-part," the general layer-by-layer fabrication
method has given "additive" software wizards a great advantage over the
5-axis guys. But, this may simply be the "moving target," which the 3-axis
and 5-axis tool path programmers may be catching up on over coming years.
 [Recognizing that no matter how fast good your software is or how fast your
spindle turns, there are challenges which simply cannot be overcome by
programming, and rotating an end mill, etc.]

5. There are also, of course, the potentials which Brock Hinzmann is
wondering about:

<Subj: RE: updated webb page announcement
<Date: 97-06-05 00:04:14 EDT
<From: (Brock Hinzmann)

>From an attempted "objective" viewpoint, it seems that subtractive methods
will maintain serious competitive advantages for a remarkably large
percentage of general "fabrication" work (meaning creating shaped material) .
 The additive methods are adding tremendous capabilities, but it's going to
be a very interesting competition and evolution. Especially interesting how
the additive and subtractive interact and stimulate...

Norm Kinzie
Laminar Systems, Inc.

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