3D CAD Design
3D wire framing was the next step in CAD wherein 2D sections were given depth to extrude. Sections were revolved around an axis and swept along trajectories to create 3D forms. Surface modeling was another advancement wherein surface skins were created using typical wire framing three dimensional commands. Solid modeling was the biggest advancement in 3D CAD. [read more]
Urethane Prototypes
Cast urethanes (polyurethanes) are often used to produce prototype parts where properties similar to those of finished plastic injection molded parts are needed. Most commercial products, medical devices and consumer goods utilize parts made from injection molded polypropylene (PP) or polyethylene (PE) plastics. These production parts can be cost effectively and easily simulated on a prototype scale or limited low volume production basis using cast urethanes. A wide range of material properties can be achieved with prototype urethanes in order to evaluate a product on a number of criteria. Urethanes are available in many colors and have various optical properties. In many cases a production quality finish or high level of aesthetic quality is desired at the prototype stage. There may be a need to determine the safety and durability of a product as well certain product performance features.
The most common urethane casting process utilizes a "master pattern" or replica of the finished design made from either a rapid prototype process such as SLA or in some cases a hand crafted process. Liquid RTV silicone is then poured over the master pattern which flows in and around the part surfaces, taking a significant level of detail due to it's high viscosity. The cured silicone mold is then split and master pattern is removed leaving the cavitated or negative volume of the part behind. The RTV mold is then used to cast the urethane prototype parts which often require very little cleanup. After some minor post finish processing, painting in some cases, these prototype urethane parts are ready to be unveiled. Whether a product is being studied for DFMA (design for manufaturablility and assembly), being evaluated for it's "curb appeal" or being unveiled at a trade show, focus group or sales meeting, a urethane prototype can often expedite the overall time to market and often times can pay huge dividends when time is of the essence.