Stretch Film Terminology

Dart Drop: A commonly used test to measure the puncture strength of a stretch film. It's conducted by dropping a semi-circular shaped object onto the film.

Elastic Recovery: The ability of a stretch film to recover to its original shape after being stretched.

Film Memory: The ability of the film to return to its pre-stretched form. Enabling the film to maintain a tight load during transportation.

Banding: Banding is the act of applying multiple wraps of stretch film to a certain area of a load to reinforce and/or unitize a number of layers or products.

Stretch Ratio: The ratio of the final length of the stretched film to its original length, indicating the degree of elongation.

Necking: The localized thinning of the film during stretching, typically occurring in areas of higher stress concentration.

Elongation at Break: The percentage increase in length of the film at the point of rupture compared to its original length.

Cast film: Molten plastic extruded over full width of a die, then cooled and crystallized over a drum. Cast film typically is quieter, more transparent, and glossier than blown film because of this process.

Machine Direction (MD): The direction of the stretch film's orientation during manufacturing, typically aligned with the direction of travel on production equipment.

Transverse Direction (TD): The direction perpendicular to the machine direction, affecting the film's width.

Cling: Cling is a bonding agent added to stretch film to increase the stickiness quality of the film. This is desirable to allow the layers of stretch film applied to bond to the previous layers effectively creating a single wall of stretch film. Depending on the desired effect the bonding agent is applied to one or both sides. It is most commonly applied using co-extrusion where the bonding agent is a layer that is co-extruded during the manufacturing process.

Resin Grade: The type and quality of resin used in stretch film manufacturing, affecting film properties such as clarity, strength, and elongation.

Coextrusion: The process of combining multiple layers of different polymers to create a stretch film with enhanced properties, such as barrier properties or puncture resistance.

Gauge: Refers to the thickness of the stretch film, usually measured in micrometers or mils.

Gloss: The amount of light reflected from a film's surface. Cast stretch films tend to have a higher gloss than blown stretch films.

Haze: The cloudiness or lack of transparency in the stretch film, often measured as a percentage using a haze meter.

Residual Elongation: The amount of stretch retained by the film after relaxation, influencing load-holding force and stability.