Packaging material evaluation and apparatus therefor incorporating split take up drum and/or specific containment force measurement

A stretch wrap packaging material test apparatus, comprising:

• a take up drum configured to receive a web of packaging material, wherein the take up drum is rotatable about a rotational axis thereof to wind the web of packaging material about the take up drum, and wherein the take up drum includes:
• a take up drum drive configured to rotate the take up drum about the rotational axis thereof;
• first and second drum members respectively spanning first and second arcuate portions of the take up drum;
• and
• a force sensor positioned between the first and second drum members to sense a containment force imparted about the take up drum by the web of packaging material wound about the take up drum;
• a packaging material delivery system disposed upstream of the take up drum and configured to convey the web of packaging material from a packaging material roll to the take up drum during rotation of the take up drum, wherein the packaging material delivery system includes:
• upstream and downstream pre-stretch rollers configured for rotation at different rates of rotation to pre-stretch the web of packaging material prior to winding the web of packaging material about the take up drum;
• and
• upstream and downstream pre-stretch drives respectively configured to rotate the upstream and downstream pre-stretch rollers during rotation of the take up drum;
• and
• a controller coupled to the take up drum drive and the upstream and downstream pre-stretch drives to control rates of rotation of the take up drum and the upstream and downstream pre-stretch rollers, the controller further coupled to the force sensor to record the containment force sensed by the force sensor during rotation of the take up drum and the upstream and downstream pre-stretch rollers.

A stretch wrap packaging material test apparatus, comprising:

• a take up drum configured to receive a web of packaging material, wherein the take up drum is rotatable about a rotational axis thereof to wind the web of packaging material about the take up drum, and wherein the take up drum includes:
• a take up drum drive configured to rotate the take up drum about the rotational axis thereof;
• a substantially cylindrical outer surface about which the web of packaging material is wound;
• a first drum member spanning at least a first arcuate portion of the take up drum and supporting at least a first portion of the substantially cylindrical outer surface;
• and
• a force sensor coupled to the take up drum to sense a containment force imparted about the substantially cylindrical outer surface of the take up drum by the web of packaging material wound about the take up drum, the force sensor configured to sense the containment force at least in part by sensing an applied force to the first drum member;
• and
• a packaging material delivery system disposed upstream of the take up drum and configured to convey the web of packaging material from a packaging material roll to the take up drum during rotation of the take up drum.

A method of determining containment force for a stretch wrap packaging material, the method comprising:

• supplying a web of packaging material from a packaging material roll to a take up drum using a packaging material delivery system disposed upstream of the take up drum;
• rotating the take up drum about a rotational axis thereof to wind the web of packaging material about the take up drum;
• and
• sensing a containment force imparted about the take up drum by the web of packaging material wound about the take up drum using a force sensor positioned between first and second drum members respectively spanning first and second arcuate portions of the take up drum.

A method of evaluating a stretch wrap packaging material, the method comprising:

• conveying the packaging material from a packaging material roll to a take up drum through a packaging material delivery system that applies a controlled stretch to the packaging material prior to the packaging material being wrapped around the take up drum;
• varying the controlled stretch while conveying the packaging material from the packaging material roll to the take up drum to determine an incremental containment force applied to the take up drum by the packaging material wrapped around the take up drum at varying amounts of controlled stretch;
• and
• determining a specific containment force for the packaging material at each of the varying amounts of controlled stretch using the determined incremental containment force at each of the varying amounts of controlled stretch.