Method and apparatus for testing stretch film

An apparatus for testing the properties of stretch film comprising:

• first and second means for anchoring a roped web of stretch film at two locations;
• means for moving the first and second anchor means away from each other for stretching an intermediate portion of the roped web a first distance in a first direction between the first and second anchor means;
• means for engaging and displacing the intermediate portion of the roped web a second distance along a second direction transverse to the first direction and relative to the anchor means;
• and
• means for measuring the tension force in the stretched roped web when it is displaced in the second direction.

An apparatus for alternatively testing the relative stretchability, relative restretch force and relative moldability of stretch film comprising:

• first and second means for anchoring a roped web of stretch film at two locations;
• means for moving the first and second anchor means away from each other for stretching an intermediate portion of the roped web a first distance in a first direction between the first and second anchor means;
• means for securing peripheral portions of a sheet of stretch film and for exposing a central portion of the sheet of stretch film for deformation in a second direction transverse to the first direction;
• means for displacing the intermediate portion of the roped web a second distance along the second direction and relative to the anchor means, and for alternatively displacing the central portion of the sheet of stretch film relative to the peripheral portion of the sheet of stretch film a third distance in the second direction;
• and
• means for measuring the tension force in the stretched roped web when it displaced in the second direction, and for alternatively measuring the tension force in the sheet of stretch film when it is displaced in the second direction.