What is B-FILMCAD 2?

B-FILMCAD 2 is a software package for simulating tubular blown film processes (from die to frost line). It predicts bubble thickness, film temperature and machine direction (MD) and transverse direction (TD) strain rates and stresses, as well as the inflation pressure profile in systems with venturis. It can be used for the analysis, control or optimization of blown film processes.

B-FILMCAD 2 is a completely new version of the software. It comes in the form of a custom Microsoft Excel spreadsheet, which takes advantage of the familiar and flexible interface of Excel and the power of the Excel Solver. Numerical inputs and outputs appear on a single worksheet, and following solution of the model equations the output plots are created automatically for customization and printing by the user.

What is needed to solve problems?

No knowledge of the mathematical methodology of the simulation is required to use the program. As in all simulation programs, good process knowledge is required to identify the appropriate processing and material parameters. The user must provide geometric data on the extruder die and the air ring, and line operating conditions including mass flow rate, blow-up ratio, final film thickness and frost line height. The bubble shape profile is computed based on the given inputs.

What material parameters are needed?

A special viscosity function is used within B-FILMCAD 2 which is a modified form of an exponential viscosity function. It is used to describe the behavior of viscosity over a wide temperature range from flowing melt to solidification. Good viscosity data over this wide temperature range are needed. As well, the user must provide values of melt density and heat capacity.

How can we evaluate the performance of different polymer grades or the performance of a blown film line?

Material differences are incorporated in the viscosity model. Different materials, of course, exhibit different stress relaxation times. Production rate, blow up ratio (BUR) and cooling can easily be changed in B-FILMCAD 2 for the prediction of bubble characteristics under different operating conditions.

How do the predictions compare to experimental data and real-life situations?

The B-FILMCAD 2 predictions have been found to be in reasonable agreement with experimental data available in the open literature including those of Gupta, Farber and Dealy, Butler and Tas. An experimental research program involving industrial production lines is currently underway.

Click to see screens from the B-FILMCAD 2 spreadsheet

Return to the List of Programs

References

V. Sidiropoulos, J.J. Tian and J. Vlachopoulos, "Computer Simulation of Film Blowing", J. Plast. Film Sheet, 12, 107-129 (1996). Revised from Tappi J. 79(8), 113-118 (1996).