Machine Design

Basics of Solids Operators

The ability to construct accurate, easily modified models is helping make manufacturers more competitive.

Some versions of solid-modeling software use primitives or boundary representations as the building blocks for modeled parts. With primitives, elementary shapes are combined in a building-block fashion to create a new shape. Boolean logic commands, such as union, difference, and intersection, aid in forming new shapes. With boundary definitions, 2D surfaces are swept through space to trace out volumes. Most systems offer several types of sweeps to help create a variety of shapes.

Advantages of solid modeling
The complexity involved in designing sculpted travel bags and luggage made Paris, France-based manufacturer Delsey go to a 3D solid-modeling CAD system to speed its product-development cycle. According to Michel Aumasson, Delsey R&D director, "One of the most significant design challenges in this industry is working with designs that have no 90° angles. Each piece sports sleekly molded surfaces with attached accessories, such as buckles, straps, handles, and zippers. SDRC's I-DEAS software and Wavefront's high-end graphics product let us surmount these engineering tasks and create realistic, accurate solid models that help us present products to marketing and moldmakers."

Back when the firm designed in 2D, "It was quite difficult to explain to moldmakers how complex surfaces would be correctly molded," says Aumasson. "New products would take up to 2 years to bring to market. The new technology, however, has helped us develop three new bags in just 25 months. Over time, we anticipate the system will help reduce that cycle by at least 15% more."

The Epoca, a suitcase with built-in wheels for easier transport, was designed exclusively with I-DEAS. "In the past," says CAD specialist Patrick Menard, "We had to make a lot of modifications at the prototype stage of design which caused delays and higher costs. Since the installation of the CAD system, these headaches have been significantly reduced."

Adds Aumasson, "The ability to make corrections on-screen means fewer mistakes down the line. And the capability to evaluate multiple iterations to obtain optimum designs is truly one of the biggest benefits to implementing the system." Menard also uses PC-based software to add details such as fabric patterns to his designs. "Our customers are really impressed with the realistic images we present for product evaluations. They know that what they see is what they will get," explains Menard.

According to Menard, "Using I-DEAS and Wavefront technologies, I gain time to explore new design possibilities." The I-DEAS package has let Menard create a customer-driven library of parts, saving time whenever he begins a new project. "This standardization of parts speeds design construction and allows me time to be creative."

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