Computer-aided design and optimization of profile extrusion dies for thermoplastics and rubber: a review

Abstract

A review is provided of issues and techniques in design and optimization of profile extrusion dies for thermoplastics and rubber, with particular emphasis on unplasticized polyvinyl chloride and rubber compounds. Traditional profile die design methods are contrasted with computer-based ones, with respect to efficiency and economic benefits. The main types of die construction are outlined. Physical phenomena relevant to the design and performance of dies are summarized, including: rheology and kinematics of the flow, wall slip, extrusion instabilities, residence time and degradation, extrudate swell, draw-down, and thermal effects. Approaches and strategies for die design are explained, including: flow balancing – with guidance from analytic flow results, the Avoid-Cross-Flow strategy, use of flow separators, and designing for extrudate swell. Published computer simulations of die flow used to assist with design are reviewed. Introducing automatic die design, the structure and elements of a computerized design optimization environment are set out. Key components and options within this are described, including: objective functions, constraints, design variables, optimization algorithms, design parameterization and flow domain meshing, and optimization strategies. Published implementations of computerized profile die design optimization are described. Automatic design optimization is compared with the work of a designer assisted by flow simulations in the industrial environment, showing how substantial reductions in demands on the designer's time are possible. The nature and potential of robust design is outlined, with techniques for its implementation. Conclusions are drawn as to the present state of the art in computer-assisted profile die design and optimization, and potential advances.

Optical coherence tomography based particle image velocimetry (OCT-PIV) of polymer flows

“…Mathematical modelling of polymer flow is of particular interest in extrusion die design, where the melt flow must be balanced to provide a more uniform velocity across the die exit [1]. Moreover, this flow balance must be achieved with a minimal pressure drop.…”

“…polypropylene or polyethylene, usually assume wall adhesion. Therefore, the measurement of the velocity distribution, as well as the degree of wall slippage is important for choosing correct boundary conditions in flow simulations [1,2].…”

Variation and artificial neural network prediction of profile areas during slant type taper profiling of triangle at different machining parameters on Hastelloy X by wire electric discharge machining

“…[1][2][3][4] These components have application in the manufacture of precision parts like injection mould dies, blanking dies, injection nozzles etc. [5][6][7] The traditional guide adjustment mechanism for tapering causes the wire to bend which increases wire cut, causes guide wear, incomplete flushing, etc. As the wire is flexible, it is subjected to deformation and many other parameters also cause imprecisions during machining.…”

Improving the automated optimization of profile extrusion dies by applying appropriate optimization areas and strategies

“…By this the number of real iterations can be reduced [4] For example the Finite Element Analysis (FEA) can be used to numerically solve the flow through the die. With such an approach several dies can be tested and only the best is chosen for further examinations.…”

“…Especially the focus lies on combining flow simulation with automated geometry deformation of the flow channels to improve the homogeneity of the melt flow [4,5,6,7,8,9,10,11,12].…”