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[September 2001]
Eljer Takes Up CAD for Surface Modelling
Eljer Plumbingware, one of the US majors in vitreous china bathroom ware, has gone beyond 2D and 3D CAD and has even moved past solid modelling, to focus on surface modelling with Delcam's PowerSHAPE. Delcam explains that for the stylised and ergonomic surfaces of sinks, pedestals, bidets and WCs, no other form of CAD works quite so well. It states that 2D is too simplistic, 3D wireframes lack sufficient design information and solid modelling is undesirable because of its difficulty in manipulating complex geometry.
"The CAD issue for us comes down to the speed and familiarity of hand modelling, which we still use extensively, contrasted with the quality and consistency of designs done with CAD," said Jim Neumann, Manager of Manufacturing Support for Eljer in Dallas. "We find that quality and consistency translate directly into higher yields in the factory."
Dave Scope, a design engineer for Eljer, adds: "With PowerSHAPE, we get a better, cleaner model. The turns and radiuses between surfaces are much better, and the surfaces themselves much smoother. The old way, doing models by hand, gave us slightly irregular shapes."
Sinks, WCs and bidets are modelled about 12.5% oversize to accommodate slip casting's high shrinkage. From the CAD model, a case master model is made. In the factory, production moulds are generated continually from this master tooling.
"If the model is not right in the beginning, the fired piece will sag and crack," said designer Robin Coven. "We have to be able to change the model's geometry dynamically and quickly. PowerSHAPE lets us do that just by clicking and dragging surfaces. For that, we make extensive use of PowerSHAPE's Intelligent Cursor. We use it for everything and it really saves us a lot of time.
"the biggest short-term benefit is that models can be revised while they are still on the computer screen. The biggest long-term benefit is the greater number of A-grade pieces coming from the kiln."
ENDS