What is Yield Strength?

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Yield Strength is the amount of stress a material can withstand before it begins to permanently deform or change shape. It is the point at which a material stops returning to its original shape after a force is removed.

In the packaging industry, yield strength is important when assessing the durability and performance of materials such as plastic films, steel strapping, metal components and rigid packaging materials.

How Does Yield Strength Work?

When force is applied to a material, it initially stretches or bends elastically, meaning it returns to its original shape once the force is removed.

However, when the force exceeds the material's yield strength, permanent deformation begins to occur.

For example, when steel strapping is tensioned around a pallet, it must withstand the applied force without permanently stretching or losing its ability to secure the load.

Why is Yield Strength Important in Packaging?

Yield strength helps determine whether a packaging material can withstand the forces experienced during packing, handling, storage and transportation.

• Steel Strapping: Helps determine how much tension can be applied before permanent stretching occurs.
• Plastic Packaging: Provides an indication of how a material responds to stress before permanent deformation.
• Rigid Packaging: Helps assess resistance to permanent bending or distortion under load.
• Packaging Machinery: Important when selecting metal components that must withstand repeated mechanical forces.

Yield Strength vs Tensile Strength

Although related, yield strength and tensile strength measure different material properties.

Yield strength is typically measured in megapascals (MPa) or pounds per square inch (psi).

In simple terms: Yield strength measures how much stress a packaging material can withstand before it permanently changes shape, helping determine its suitability for different packaging applications.