Drawdown Ratio Calculator - Calculator Academy

Calculate extrusion drawdown ratio, missing die, tip, product or core diameter, and draw ratio balance from four diameter inputs.

Draw Down Ratio Formula

The following formula calculates area-based Draw Down Ratio for annular extrusion. Use consistent diameter units, with die greater than tip and product greater than core. Select a solve mode to calculate DDR, a missing diameter, or DDR with draw ratio balance (DRB = (DD/DT)/(PD/CD)). These geometric ratios alone do not determine process suitability.

DDR = (DD² - DT²) / (PD² - CD²)

Where DDR is the Draw Down Ratio (unitless)
DD is the diameter of the extrusion die
PD is the product outer diameter
DT is the outside diameter of the tip
CD is the core diameter (for example, the product inner diameter or the diameter of the wire/conductor being coated)

How to Calculate Draw Down Ratio?

The following example problems outline how to calculate Draw Down Ratio.

Example Problem #1

First, determine the diameter of the extrusion die.
- The diameter of the extrusion die is calculated to be 5.
Next, determine the product outer diameter.
- The product outer diameter is measured to be 2.
Next, determine the outside diameter of the tip.
- The outside diameter of the tip is found to be 3.
Next, determine the core diameter.
- This is measured to be 1.
Finally, calculate the Draw Down Ratio using the formula above:

DDR = (DD² – DT²) / (PD² – CD²)

The values given above are inserted into the equation below and the solution is calculated:

DDR = (5² – 3²) / (2² – 1²) = (25 – 9) / (4 – 1) = 16/3 = 5.33

Example Problem #2

The variables required for this problem are provided below:

diameter of the extrusion die = 10

product outer diameter = 7

outside diameter of the tip = 6

core diameter = 4

Test your knowledge using the equation and check your answer with the calculator above.

DDR = (DD² – DT²) / (PD² – CD²) = ( )