The foam industry is rapidly consolidating and becoming increasingly driven by cost factors. Time-to-market is key for the design of foam products, such as flexible insulation products, which Armstrong manufactures for the heating, cooling, and plumbing markets. Die-making is a barrier in decreasing time-to-market, particularly with the demand for cheaper, lighter, and custom profiles. More an art than a science, die-making still depends almost entirely on trial and error.

CFD helped to reduce the number of die iterations leading to a cut in cost and time-to-market.

Working together, Armstrong and Fluent have shown how CFD can augment the traditional trial-and-error design process.

In this project, partially funded by the European Commission, Armstrong Insulation Products provided geometrical and rheological data. Fluent provided POLYFLOW software and expertise in simulation of foam production and extrusion. The research team's goal was to show that CFD simulation can predict the die geometry necessary for achieving the desired shape. As such, CFD provides a valuable "first guess" from which to start the die-making process, ultimately reducing overall time and increasing performance.

Two foam profiles were studied - one simple and one complex. The single bubble growth model in POLYFLOW was used. This model divides the foam into spherical microscopic unit cells of equal and constant mass, each made up of a liquid envelope and concentric spherical gas bubble. This model describes important qualitative features of a real system of numerous bubbles growing in close proximity. Rheological data provided by Armstrong allowed for fitting a power law for the viscosity, while the foaming model parameters were chosen in order to have the right densities at the inlet and outlet, and to obtain reasonable bubble sizes.

Estimated return on investment on an annual basis from using modeling for die design

Fluent used POLYFLOW's unique automated design tool to calculate the optimal die geometry. The design was built and tested. Some differences existed between the numerical results and the experimental shape, but it took minimal trial-and-error to adjust the die and obtain the desired result. The benefits of this approach were clearly shown as the cost of die design and time-to-market were significantly reduced. The return on investment for using POLYFLOW for die design assistance quickly becomes significant when the number of dies produced per year exceeds 3 of complex shape or 10 of a more simple geometry.

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