Optimization of High Speed Wire Drawing Using Finite Element Analysis

Open Access
Cunningham, Daniel J
Graduate Program:
Engineering Mechanics
Master of Science
Document Type:
Master Thesis
Date of Defense:
November 11, 2008
Committee Members:
  • Ivica Smid, Thesis Advisor
  • Wire Drawing
  • Finite Element Analysis
The process of pulling a wire through a series of conical shaped dies which incrementally reduces its cross sectional area is known as wire drawing. These wire drawing dies are subjected to extremely high stresses while at the same time expected to survive long service lifetimes. Finite element modeling is used to model the interactions of these materials throughout the wire drawing process. These models show that during the drawing process the wire at the exit of the die can reach local stresses of roughly 150% of its yield strength. The required drawing force and die stress are monitored at many different drawing conditions. As the drawing speed of the wire is increased there must also be an increase in die approach angle in order to maintain a minimal stress state. The bearing length and reduction ratio of the die must be optimized for different hardening exponents. Brittle materials with low hardening exponents contain strain gradients throughout the thickness of the wire which results in tensile stresses in the outer edges of the wire and compressive stresses near the center. Materials with higher hardening exponents contain less significant strain gradients but exhibit more elastic rebounding after drawing. Optimized die geometries are specific to a desired application and understanding the relationship between the die geometry and the resultant stress states allows improvements on existing drawing techniques as well as the possibility for drawing new materials.