POM Earns U.S. Patent for Closed-Loop Optical Feedback System

8 November 2000
POM Earns U.S. Patent for Closed-Loop Optical Feedback System
              Exclusive system allows unmanned fabrication using
          company's laser-based Direct Metal Deposition(TM) process

    DETROIT, Nov. 8 The POM Group, Inc., announced today that
it has been awarded a United States Patent for the closed-loop optical
feedback system it uses with its DMD(TM) (Direct Metal Deposition) process.
U.S. Patent No. 6,122,564, "Apparatus and Methods for Monitoring and
Controlling Multi-Layer Laser Cladding," makes it possible to create fully
dense metal parts using powdered metal and an industrial laser, without the
need to physically monitor the deposition process.
    "By offering this capability as part of our DMD solution, we're able to
reduce customer lead-times by speeding the time it takes to go from idea to
finished component," said Jyoti Mazumder, POM's chief executive officer and
co-inventor of the closed-loop optical feedback system.  "This is achieved
through the system's ability to automatically and continuously maintain
specifications during the deposition of a part."
    DMD is POM's trade name for its laser-based fabrication technology that
produces 100% dense metal products "from the ground up" using powdered metal
-- directly from a CAD file.  A significant advance in metalworking, DMD
rapidly produces molds, dies and other metal components with superior material
properties, in less time, than is possible with traditional fabrication
technologies.
    The overall DMD technology is the result of blending five common
technologies: lasers, CAD, CAM, sensors and powder metallurgy.  The DMD
process creates or reconfigures a part by focusing an industrial laser beam
onto a metallic workpiece or preformed part, creating a molten pool of metal.
A stream of metallic powder is then injected into the melt pool, increasing
the size of the molten pool.  By moving the laser back and forth under CNC
control, tracing out a pattern defined by the CAD geometry, the new or
modified part is built ... line by line, one layer at a time.
    With this process and its translating laser energy source, the molten pool
solidifies at a rapid rate, resulting in a fully dense, refined
microstructure.  The DMD(TM) process results in parts with physical properties
that exceed those of conventional wrought of cast materials, providing
superior quality and increased strength.
    By tying closed-loop optical feedback capability to the DMD process, the
size and composition of the molten pool is automatically monitored, controlled
and corrected to keep dimensions accurate throughout the deposition.
    "Unlike vision systems -- which can see what's going on, but do nothing to
correct -- our closed-loop system takes the information it sees and gives it
back to the machine," explained Mazumder.  "Without this capability, one would
have to stop the machine periodically and manually correct the areas in which
specifications went out of control.  And in today's market, even the smallest
time delays can jeopardize a manufacturer's competitiveness."
    POM, based in Plymouth, Mich., is the world's first companies to introduce
a commercially viable, reliable, laser-based direct metal fabrication
processes capable of producing prototype and production tooling using premium
tool steel metals that are mandated for all plastic injection molding and die
casting markets.  A minority owned and operated service bureau and OEM, POM
provides DMD process equipment as well as finite element analysis, CAD/CAM,
fabrication and repair services.