120 Inch Diameter Contoured
Aluminum Chandelier Base For New Theater Lobby Produced
By Acme Metal Spinning -- Process Solves One-Of-A-Kind Manufacturing
production methods for large, one-of-a-kind metal parts can pose
problems in terms of turnaround time, quality and economy. But
there are contract manufacturers out there who find one-, two-
or four-of-a-kind work challenging and an important aspect of
Acme Metal Spinning, a well-known 100
year old metal spinning company, recently fabricated a large,
primary outer ring structure for a unique, one-of-a-kind theater
lobby decorative lighting chandelier.
Now hanging in the recently opened Pacific
Theater of San Diego, California, the elegant light fixture is
an interesting example of creative design and modern manufacturing
processes. Housing 16 F50BX lamps and 8 two-lamp electronic dimming
ballasts, the 6 foot diameter pendant is an energy efficient
design, producing sufficient lumens to light the lobby area with
a soft, pleasant glow. It is suspended 108 inches from the theater
ceiling by 4 large brass chains. Its graceful contours, subdued
colors and soft lighting blend beautifully into the coved ceiling
Pacific Theater, San Diego lobby
chandelier by Advent Lighting features metal spun 120 inch dia.
x 4" deep trim pan outer ring.
The light pendant was manufactured by
Advent Lighting Corporation of Greenville, Wisconsin, manufacturer
of specification grade architectural lighting. The theater pendant
project began with KMA Architects and Engineers of San Diego,
who originated the concept. Advent Lighting was then called in
to produce the actual pendant assembly.
Because of the chandelier's size, the
outer trim pan ring was necessary to provide the support structure
for holding eight acrylic panels in place which formed the light
fixture's globe. The ring, along with an aluminum T-bar, provided
the base structure which gave the fixture the needed strength
and rigidity for holding the l8 lamps and wiring assembly.
METAL SPINNING PROCESS SELECTED
TRIM PAN OUTER RING STRUCTURE
Since the chandelier was a one-of-a-kind
undertaking, methods to produce the large outer component were
limited. Extrusion processes couldn't handle the large width
to length size material requirements. The seamless, smooth contours
would be difficult to create using hand fabricating techniques.
And because only one finished part was needed, stamping processes
requiring expensive permanent tooling were ruled out, further
limiting the manufacturing options. Advent Lighting decided to
call in Acme Metal Spinning of Minneapolis, Minnesota to see
if they could produce the needed outer ring.
"Metal spinning was the most practical
method to use," reported Bruce Johnson, president of Acme
Metal Spinning. "It's fast, provides a very attractive finished
appearance and can be produced as a single part without the need
for expensive, permanent tooling."
To fabricate the part, Acme began with
two 130 inch square sheets of .190" thick aluminum. Cut
to form a semi-circle, the two parts were welded together at
the ends to form a donut-shaped flat piece of aluminum. Weld
beads were ground smooth. Then Acme designed and produced a laminated
wood tooling pattern. This is a standard process used in the
metal spinning industry to produce tooling. What made this particular
part and the tooling for it unique was its large size. Acme designed
the tooling on its CAD system. The laminate wood structure was
constructed and assembled with everyday woodworking tools and
then machined to size on a 140" diameter lathe. Two workers
were required to move and position the tooling fixture using
forklift and overhead crane.
Chandelier's finished trim pan
outer ring shown in wood tooling pattern.
Once complete, the tooling was mounted
in a Lieco 140 inch capacity spinning machine, one of the largest
machines of this type in the United States. This process required
just under 6 hours while the actual spinning process took only
about an hour for the one part. The spinning operation combined
rotation and force. Roller-like tools are pressed against the
whirling blank as it turns on the lathe, flowing and forming
the material around the wooden tooling pattern which was cut
in the shape of the finished part. The finished part had a smooth,
consistent finish, including the near invisible welds and required
no additional finishing operations by Acme.
Lieco hydraulic spinning lathe
used to produce the trim outer ring is CNC controlled.
Following shipment to Advent Lighting,
the part was sprayed with a bronze paint, assembled and made
ready for hanging in the Pacific Theater. According to Acme,
this was the largest light fixture component it has ever produced.
FOUR-OF-A-KIND METAL SPUN ELEVATOR
DOMES ADD VISUAL DRAMA AND ELEGANCE
Exquisite lobby design esthetics in public
buildings using metal spinnings isn't limited to lighting fixtures.
The use of metal spinning for architectural adornment - functional
and decorative - reach as far as the designers imagination. Case
in point, large domes produced by Acme which were trimmed into
halves to form the top end caps for two elevators in a Mid Eastern
country hotel lobby.
The domes were produced from 3/16"
thick, type 304 stainless steel blanks measuring almost 8 feet
in diameter. As with the aluminum chandelier base, tooling was
designed on Acme's CAD system. The wooden tooling was machined
on a 140 inch diameter lathe.
Acme's spinning lathe for this job was
customized to enhance the part size and overall finish quality.
Acme used an annealing process during production to help relieve
material stress and work hardening. Once shaped, the 72"
dia. x 36" deep domes were polished to a number 4 finish,
reflecting light with an unusual brilliance, adding a celestial
look and feel.
Four final 8 foot diameter domes
were prepared for shipping.
Besides architectural and light fixture
components, Acme produces air-moving, food processing, agricultural
parts and cryogenic tanks. Its specialties are hemispherical
and large diameter spinnings.