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Sheet bowing in thermoforming
Author(s) -
Vodak P.B.,
Mix A.W.,
Giacomin A.J.
Publication year - 2011
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.22029
Subject(s) - thermoforming , bowing , dimensionless quantity , materials science , slab , thermal expansion , temperature gradient , mechanics , composite material , structural engineering , physics , engineering , philosophy , theology , quantum mechanics
Sheets to be thermoformed are often heated unevenly, with a higher temperature above the sheet. This results in upward bowing of the sheet, and this is caused by thermal expansion. We combine the analytical solution for the temperature gradient in a slab heated by radiation with a relationship developed from the cylindrical geometry of the sheet as it bows. We thus derive a dimensionless equation for sheet bowing as an implicit function of time for both top and dual heating. We thus uncover a new dimensionless group which we call sheet bowability . We find good agreement between our theory and our new top‐heated sheet bowing measurements. We provide a worked example so that the engineer can see how to apply our results. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers