From: Marshall Burns (
Date: Mon Jun 12 2000 - 21:25:38 EEST

>I've heard about a system called COLAMM from the Japanese company Mitsui
>but I can't find any informations about it.
>Can anybody provide me with infos about that system?
>Dipl.-Ing. Holger Löffler

Dear Holger,

    Below is an excerpt from my book on the Mitsui COLAMM. Remember, this
was published in 1993, so it's not quite up to date.

Best regards,
Marshall Burns
President, Ennex Corporation
Los Angeles, USA, (310) 397-1314

Excerpt from "Automated Fabrication" by Marshall Burns
Copyright (c) 1993, Ennex Corp. All rights reserved.

The COLAMM: Mitsui

    The Mitsui Engineering and Shipbuilding Company of Tokyo, Japan, began
offering a photopolymer fabricator called the COLAMM (Computer-Operated,
Laser-Active Modeling Machine) in 1991. The company reports having sold one
unit to a job shop. Data on the machine were not received in time for
inclusion in Chapter 2. A brief description is given here of the technique
used in that system and of some other interesting work that has come out of
the Mitsui labs.

    The COLAMM is unique in that objects are built from the top down, rather
than bottom up. This “ascending suspension” method is illustrated in Figure
2-11. The first (top) cross section of the object is created by scanning,
from below, a thin layer of resin between a transparent window plate and the
underside of a suspension plate. The chemistry of the materials involved is
such that the cured polymer adheres to the suspension plate, and not to the
window plate. The first layer is thus affixed to the suspension plate, which
is raised by an increment to allow a new layer of resin to flow onto the
window for scanning. The object is thus built suspended from the ascending
suspension plate.

    This technique may allow faster laser scanning by curing the resin at an
interface with glass, not air, since isolation from oxygen improves
photosensitivity of the resin. (For more on this subject, see Photocuring
through a Contact Window below.) However, since the object grows in
suspension and each layer must therefore support all new layers below it,
the method probably requires some kind of supporting mechanism, as shown in
Figure 2-11, in order to be practical for shapes with narrow necks.

    In the late 1980s, Mitsui explored several alternative approaches to
photopolymer-based automated fabrication before deciding to focus
exclusively on the technique described above. The following ideas were
described in Mitsui patent applications, but the company has stated that it
does not intend to pursue these directions in the near term.

    One Mitsui idea combines photocuring with robotically guided extrusion.
Photopolymer resin is ejected from a nozzle and immediately cured by
incident light. What makes this idea most interesting, however, is that the
nozzle is fed from various input ports, so that it is capable of ejecting a
variety of resins or mixtures of resins. The results can be variations in
color and other physical properties.

    Other proposals from Mitsui involve modifying the profile of the
incident light beam to cure rectangular blocks rather than the parabolic
“bullets” formed by a Gaussian laser, passing the incident light through a
screen resulting in the microscopic dispersal of cured regions in an uncured
matrix, and mixing the photocuring resin with short fibers or other filler
material to reduce curing distortion.

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