Different Friction Coefficients at Different Positions of Superplastically Formed Parts

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

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Author(s)

Detail(s)

Original languageEnglish
Pages (from-to)741-746
Journal / PublicationMaterials Science Forum
Volume304-306
Online published23 Feb 1999
Publication statusPublished - 1999
Externally publishedYes

Conference

Title2nd International Conference on Towards Innovation in Superplasticity
Location
PlaceJapan
CityKobe
Period21 - 24 September 1998

Abstract

The current study is to discuss that the degree of lubrication might be significantly different at different positions of a SPFed product. Numerous comparisons between experimental and predicted thickness profiles for open-die free bulging or close-die forming were made, using simulations based on systematic combinations of m, n and μ values. Current results suggest that the experimental thickness profiles fit best with the simulated distribution when using m=0.5 together with µ=∞ for the die entry portion and µ=0.01 for the bottom region. It we use the same friction coefficient for all positions, the predicted thickness profiles can never be close to the experimental ones. It was latter found that the lubricant powders would slide down along with the deformed sheet, from the upper die entry position down to the bottom center. The lubrication effect after the onset of SPF becomes different at different positions. There is almost no lubrication at the die entry (hence µ~∞) and near complete lubrication and free sliding at the central bottom region (hence µ~0). The discrepancy in experimental and predicted thickness profiles might not simply due to the wrong estimation of m-values, but could also be owing to different lubrication effects at different positions.

Research Area(s)

  • Friction Effect, Lubricant Powders, Superplastic Forming

Citation Format(s)

Different Friction Coefficients at Different Positions of Superplastically Formed Parts. / Chen, T.-R.; Huang, J.C.; Hwang, Y.M. et al.
In: Materials Science Forum, Vol. 304-306, 1999, p. 741-746.

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review