﻿ Moving Boundary Analysis
Manufacturing Solutions

# Moving Boundary Analysis

L = Billet Length

L1 = Butt Length (Typically 0.5 inches)

L2 = Pocket Length

## Flat die without pockets (L2 = 0)

 • Extrusion direction should be positive Z-axis.
 • Mesh such that Z=0 at the front end of the billet.
 • If L1 is the butt length, define a mesh such that it has at least two elements in between Z = 0 (die face) and Z = -L1/2. These elements will not move during the analysis.

## Flat die with pockets (L2 > 0)

 • Extrusion direction should be positive Z-axis.
 • Mesh such that Z=0 at the front end of the billet.
 • If L1 is the butt length, define a mesh such that it has at least two elements in between Z = 0 (die face) and Z = -L1/2. These elements will not move during the analysis.

## Hollow Die

 • Extrusion direction should be positive Z-axis.
 • Mesh such that Z=0 at the front end of the billet.
 • If L1 is the butt length, define a mesh such that it has at least two elements in between Z = 0 (die face) and Z = -L1/2. These elements will not move during the analysis.
 • Collapsed elements in the billet become very thin in the extrusion direction. This might lead to bad element-grading in the butt area. Therefore, it is advisable to occasionally refine elements in L1 area in the Z-direction.
 • If using higher-order elements (Hex20 or Hex27), Butt's boundary should match element faces (element faces should fall at Z= -L1).