The image above represents the apparent shear stress | slit die.

To compute for apparent shear stress | slit die, three essential parameters are needed and these parameters are **height of die (h), pressure gradient (ΔP)** and** flow length (L).**

The formula for calculating the apparent shear stress | slit die:

τ_{app} = ^{h . ΔP} / _{2L}

Where:

τ_{app} = Apparent Shear Stress | Slit Die

h = Height of Die

ΔP = Pressure Gradient

L = Flow Length

Let’s solve an example;

Find the apparent shear stress | slit die when the height of die is 7, pressure gradient is 12 and the flow length is 16.

This implies that;

h = Height of Die = 7

ΔP = Pressure Gradient = 12

L = Flow Length = 16

τ_{app} = ^{h . ΔP} / _{2L}

τ_{app} = ^{7 . (12)} / _{2(16)}

τ_{app} = ^{84} / _{32}

τ_{app} = 2.625

Therefore, the **apparent shear stress** is **2.625.**

**Calculating the Height of Die when the Apparent Shear Stress, Pressure Gradient and the Flow Length is Given.**

h = ^{τapp x 2L} / _{ΔP}

Where:

h = Height of Die

τ_{app} = Apparent Shear Stress | Slit Die

ΔP = Pressure Gradient

L = Flow Length

Let’s solve an example;

Find the height of die when the apparent shear stress | slit die is 32, the pressure gradient is 10 and the flow length is 8.

This implies that;

τ_{app} = Apparent Shear Stress | Slit Die = 32

ΔP = Pressure Gradient = 10

L = Flow Length = 8

h = ^{τapp x 2L} / _{ΔP}

h = ^{32 x 2 (8)} / _{10}

h = ^{32 x 16} / _{10}

h = ^{512} / _{10}

h = 51.2

Therefore, the **height of die **is **51.2.**

Continue reading How to Calculate and Solve for Apparent Shear Stress | Slit Die | Polymer & Textile