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Solid‐phase backward extrusion of thermoplastics
Author(s) -
Okine Richard Kafue,
Suh Nam P.
Publication year - 1982
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760220502
Subject(s) - extrusion , materials science , composite material , polypropylene , die (integrated circuit) , slab , flange , thermoplastic , polystyrene , polycarbonate , plasticity , phase (matter) , structural engineering , polymer , chemistry , organic chemistry , engineering , nanotechnology
The backward extrusion process was studied as a means of forming projections and ribs on flat sections of thermoplastic parts. The simplified, open‐die axisymmetric and plane‐strain extrusion cases were mainly considered. The results were applied to the development of a continuous solid‐phase‐forming process. Commercial‐grade polycarbonate (PC), polypropylene (PP), and polystyrene (PS) were used in the investigation. The projection height and extrusion loads in the unconstrained extrusion were measured as a function of the initial temperature of the material, the load hold time, and geometric variables. Cold dies were used in the experiments, and the samples were kept below their melt temperatures. The dimensional recovery of the flange section of the formed samples was also measured as a function of the hold time for given initial temperature and geometric variables. The slab and the upper‐bound methods‐in plasticity analysis were used to theoretically derive the projection heights and forming loads. The degree of correlation between the predictions and the experimental results depended on the estimates used for the frictional factors at the interfaces between the deforming material and the dies.