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December 7, 1998

6 Min Read
With an egg for inspiration, CAD brings refrigerator to life

ArticleImage1610.jpgThe natural look and color of bio-design transforms the mundane refrigerator into the Oz, an Italian creation. The interior design's fit and function was demanding as well.

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If there is one basic thing refrigerators have in common, it is that they are more or less boxes, visually rectangular with 90° angles even if they have been radiused. The Oz refrigerator introduced this past summer by Zanussi, Italy's largest appliance maker, is different; it does not have a square corner on it other than where it meets the floor. Even its color is innovative. But the innovation is not confined to its design; it extends to production as well.

The 4-ft-high Oz began as an idea of Roberto Pezzetta, the director of Zanussi's Industrial Design Center, and his goals are clear and eloquently stated: "Oz is a bio-design . . . natural as opposed to artificial, passionate rather than rational." It is intended to convey warmth and harmony. "Bio-design prefers the continuity of curves to the discontinuity of straight lines and right angles."

Materials, shape, color, topology, and everything else are selected and designed to support this kind of user interface. Pezzetta specifically notes the ability of rubber and plastic to achieve this, as opposed to metal, and his design inspirations include ". . . the safe sensation of a bivalve shell, and the perfect life-protecting sanctuary of the egg."

From Concept to CAD
While this may sound like the ideas of an "artistic" designer with no link to the real world, Pezzetta and Zanussi are very aware of the realities of technology and the need to be competitive in the appliance market.

From its beginning, this project had very clear directions regarding materials and production technology. It was not an artistic project but something to be manufactured-with the bonus that Zanussi is willing to cross generally accepted boundaries and limits. Consequently, Oz is the first refrigerator with an exterior made of polyurethane. After establishing the viability of the new refrigerator design in 2-D CAD and building a carved model, Zanussi turned to a collaborator, CAD Service, also located in Northeastern Italy, to bring the Oz into 3-D reality. Maurizio Simonin, co-owner of CAD Service, notes with a smile that although Oz looks simple, achieving the high level of surface finish and general perfection of form required by Pezzetta provided real challenges to both the designer and the CAD software.

Seated at his workstation, Gianfranco Pezzutti, the designer responsible for the Oz project, nods his agreement and brings up an image of the door to illustrate. The Catia-Cadam software running on a Silicon Graphics workstation provides several specific tools for achieving and certifying surface smoothness. Using a simulation of reflected lines of light on the door's surface and zooming in to show fine detail, Pezzutti moves through the multiple iterations needed to achieve Zanussi's demanding aesthetic goals.

Pezzutti had to remain highly aware of the Oz design goals during the entire process of transforming the idea into a 3-D file. He had to always consider protective and security aspects, and user-friendliness while making it all function.

An example is the recess near the top of the door that forms the grip needed to open it. This had to be functional, ergonomically suited to the human hand, and positioned to require minimum effort. Also, notes Pezzutti, the opening has to smile, or at least give the impression of a smile, to support user-friendliness. Pezzutti made a separate parametric model of that grip/smile and worked with it until everyone agreed it looked happy and inviting.

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The challenge of surface blending and elaborate contouring was partially met by extensive computer modeling.

CAD Service's primary objective is to reduce drastically the time-to-market for a given product through state-of-the-art computer-based design and planning services. Its sister company, CSR Italia, was formed in 1987 to provide complete hardware/ software/support solutions to businesses seeking CAD capability. CSR is now one of only seven

Catia-Cadam Competency Centres (C4) certified by IBM/Dassault Systems in Italy. In addition to Catia, it offers solutions that can include Solidworks, Cadkey, Mastercam, and WorkNC on IBM, Silicon Graphics, Intel, and Hewlett-Packard platforms.

CAD Service never forgot its basic objective of reducing time-to-market. In the case of the Oz, roughly 20 percent was sliced off the projected time cycle while, at the same time, the quality of the design was maximized. Besides the injection molded body and door exteriors, attention had to be paid to fit, function, safety, and energy efficiency in every part of the unit, right down to the motor housing. Pezzutti showed how the automatic fault'checking features of the Catia software were used to help design the interior freezer door. The automatic interference detection feature in the software flashed warnings when the freezer door and the external door were not clearing properly and continued until the components achieved perfect fit. The weight of the door is carried on a spherical roller that moves across the floor as the door opens and closes. This provides smooth operation and reduces loading on the hinge but is also a safety and quality feature because the hinge can carry the door by itself. The design also meets Zanussi's requirement that a small child accidentally caught inside the refrigerator can easily push the door open.

Production Preparation
A refrigerator, even a compact model like the Oz, is too big an item to permit multiple prototypes. Even the fastest prototyping system takes considerable time and money when making something of this size. As an alternative, the software must create 3-D images so realistic that the manufacturer can make sound judgments as development proceeds.

The Oz is part of a family. Waiting in the wings are Zoe, a yellow washing machine, and Teo, a red kitchen stove/oven unit, each with the same rounded lines and friendly aspect.

Design of the molds, molding of the door and body exteriors, painting, and assembly is done by GMP Poliuretani, a specialist in PUR production. It is also accustomed to producing pieces this large or larger, such as medical device housings and furniture. The two aluminum molds for the Oz exteriors have the capability to produce 30,000 to 40,000 pieces. The Oz door and body exteriors are injection molded at low pressure (less than 10 bar), which greatly reduces the clamp force requirements for the press. The parts are molded on a 100'ton press designed and built by SEM Engineering, a division of GMP. GMP also has a moldmaking division, GMP Stampi. Painting of the refrigerator's unique "water/ice blue" finish is done in-house, and GMP provides full assembly and packaging of the finished refrigerator.

Contact Information
CAD Service/CSR Italia
Maurizio Simonin
Fiume Veneto (PN), Italy
Phone: +39 (0434) 560400
Fax: +39 (0434) 560383
Website: www.tolomeo.it/csr
E-mail: [email protected]
GMP Poliuretani SpA
Guido Furlanetto
I-31046 Oderzo (TV), Italy
Phone: +39 (0422) 718 911
Fax: +39 (0422) 718 965
Website: www.gmp-poliuretani.com
E-mail: [email protected]

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