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user review -
Early Analysis Reduces Lead Times for Sydney Olympics
Athletes' Beds
| By Laura Carrabine, Editor |
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Background
Dunlop Bedding, a division of Pacific Dunlop and the largest Australian
manufacturer of beds, was the provider of 24,000 beds that made
their debut at the Sydney 2000 Olympic Games athletes' village.
These "bunkable" beds were designed for use as single beds or stacked
to form bunks, with the option of extending the length of the beds
by 300mm for use by the taller athletes. In addition to meeting
the functional and structural requirements, Dunlop Bedding was also
looking for a fresh, modern shape and color. Dunlop Bedding decided
to manufacture the bed frames in powder-coated steel and the bedhead
panels in translucent plastic with a choice of several bright colors.
Viscount Plastics is a member of the Pacifica Group
and the largest injection molding company in Australia. Viscount
Plastics (Victoria) was chosen by Dunlop Bedding to project manage
the design and manufacture of tooling and to produce 48,000 bedhead
panels for these beds. Viscount recommended polypropylene homopolymer
as the material for the bedhead panels, as it met the requirements
for safety, aesthetics, low weight, low maintenance, ease of assembly,
and cost effectiveness.
The Project
As the translucent bedhead panel is a highly visual
part, a critical requirement was that there could be no visible
defects or warpage. "We have utilized the analysis expertise of
Moldflow's consultants for a number of years now, with filling,
cooling, and warpage analyses being important tools in the part
and mold design phases. We decided that the ability to verify and
optimize tool and product designs early in this project should help
us to reduce lead time to manufacture, avoid start up problems,
and reduce reject rates," said Mr. Vadim Gershon, Product Development
Manager, Viscount Plastics. In this project, Moldflow's consultants
were employed at the product design stage in order to optimize the
part and tool design and to verify cycle time and processing conditions.
"We wanted to ensure that we could reduce lead times of the first
acceptable samples, so that Dunlop Bedding would have enough time
to tune the other components to fit the bedhead (if necessary),
and supply beds in time for the Olympic Games," said Mr. Gershon.
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Moldflow Part Adviser software was used to verify
the gate design and location suggested by Viscount and to assess
the fill pattern. "The Part Adviser analysis confirmed that the
area of the part at the end of the longest flow path would fill
for the proposed cavity layout and wall thickness with the choice
of polymer and gate location," said Mr. Derek Hain, Senior Consultant,
Moldflow. The original design of the bedhead called for a three-piece
assembly. Viscount's engineering team suggested the use of sliding
cores driven by hydraulic cylinders, which would allow a one-piece
bedhead panel to be manufactured. Several iterative analyses were
undertaken, and it was found that the panels could be produced as
a single part instead of three separate components.
Further analyses using Moldflow’s MPI/Flow, MPI/Cool
and MPI/Warp were undertaken to verify cycle times and to ensure
the design specifications for dimensional tolerance, aesthetics,
and negligible warpage were met.
"MPI/Cool was used to verify and optimize cooling
line layouts and confirm that the processing conditions suggested
by Viscount Plastics could be used," Mr. Hain said.
The results from MPI/Warp indicated that there would
be very little warpage, as the fill pattern and the cooling lines
had been optimized by then. "The predicted warpage was negligible
and could be further reduced with fine tuning of the injection molding
machine settings and tool temperatures during manufacture," Mr.
Hain added.
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The Outcome
The initial mold trials showed that the actual
cycle time was very close to that predicted by Moldflow's software,
and the parts produced had met design specifications. "Preliminary
work conducted jointly by Viscount's engineering team and Moldflow,
as well as excellent toolmaking by Centre Tooling, has allowed us
to achieve a near-perfect part at the very first die trial. We have
probably saved at least one tool rework and subsequent die trial,
which could have cost us several thousand dollars and increased
lead time by up to 20 percent," said Mr. Gershon.
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