The role of plug design in determining wall thickness distribution in thermoforming

Peter Martin, P. Duncan

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)


An experimental investigation has been carried out into the effects of changes in plug design on the wall thickness distribution of thermoformed products. Plugs were machined with a series of geometrical variations and their effects on the process were measured. The overall results show that the plug has a crucial role in controlling the wall thickness distribution in thermoforming. Larger plugs tend to distribute more material to the base of the product, but the introduction of a small sidewall taper, base radius, or a reduction in plug diameter tend to lead to more balanced distributions. However, larger changes in any of the variables tend to destroy these benefits. It has also been demonstrated that the frictional and thermal properties of the plug are important in determining the deformation response of the sheet material. There is a clear evidence of slip in the sheet during plug contact and, although the cooling effect of the plug appears to be minimal, cooling in the highly deformed regions away from the plug appears to be a significant factor.
Original languageEnglish
Pages (from-to)804-813
Number of pages10
JournalPolymer Engineering and Science
Volume47 (6)
Issue number6
Publication statusPublished - Jun 2007

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Polymers and Plastics
  • Materials Chemistry


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