Draw Down Ratio Calculator

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

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Draw Down Ratio Formula

The following formula is used to calculate the Draw Down Ratio (area-based for annular flow). 

DDR = (DD^2 - DT^2) / (PD^2 - CD^2)

• 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

1. First, determine the diameter of the extrusion die.
   • The diameter of the extrusion die is calculated to be: 5.
2. Next, determine the product outer diameter.
   • The product outer diameter is measured to be: 2.
3. Next, determine the outside diameter of the tip.
   • The outside diameter of the tip is found to be: 3.
4. Next, determine the core diameter.
   • This is measured to be: 1.
5. 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) = ( )