![]() Castings were created both with molded wax patterns and with SLA QuickCast patterns supplied by 3D Systems.Ĭosts and timing were recorded at each step of the casting process so that an accurate comparison could be made. ![]() A double suction impeller about 15 inches in diameter (pictured right) was chosen for the study. Tech Cast and 3D Systems worked together on a study to quantify the advantages of their process. It also minimizes the material in the pattern, resulting in an almost ash-less burn that enables a cast to be created quickly and without a lot of additional steps. The resin-based patterns from Quickcast are hollow with a unique internal honeycomb structure that allows the pattern to collapse internally as it expands with temperature. The cost of QuickCast patterns is typically a small fraction of what tooling costs and they are available in less than a week, so fully machined impellers are available within three weeks. With Quickcast patterns, castings can be created without the time-consuming process of creating tooling to produce wax patterns, allowing the design to be evaluated in days instead of months. QuickCast patterns were the first direct pattern (patterns created via a 3D printing process) and are by far the most popular direct pattern technology in North America. ![]() Tech Cast uses SLA QuickCast 3D printed patterns to eliminate the need to create or modify tooling for each iteration. Tech Cast has pioneered a process that drastically reduces both the cost and time required per iteration so that pump manufacturers can go through several versions in less time than they previously could go through a single casting in the past, and spend less money in the process. They can’t afford either the time or cost required for the extra iterations to achieve optimum performance. As a result, pump manufacturers only iterate until they achieve acceptable performance. It simply isn’t practical to repetitively modify or rebuild tooling to evaluate design changes. The tools often require cores, either soluble or ceramic, to create the internal flowpaths, requiring that two tools be built. Tooling costs, especially for large impellers like those that Tech Cast manufacturers, can be very high and lead times long. In practice, however, optimizing performance in this manner has been prohibitively expensive. Consequently, achieving optimum performance is an iterative process: create a design, build the impeller, test its performance, tweak the design, and repeat the process until an optimum design is reached. Current analytical tools will give a rough estimate of pump performance, but actual performance is only determined experimentally. The fluids being pumped are often multi-component and the flow velocities and volumes are high. Designing a pump impeller that performs well is a challenge.
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