Methods and apparatus for evaluating packaging materials and determining wrap settings for wrapping machines

1. A method for determining a wrap force at which to wrap a load with packaging material, the method comprising:

dispensing packaging material to a load;

intentionally forming a tear in a portion of the packaging material;

identifying a first wrap force at which the tear exhibits a first behavior;

identifying a second wrap force at which the tear exhibits a second behavior; and

selecting a first intermediate wrap force between the first wrap force and the second wrap force, for wrapping the load.

2. The method of claim 1 , wherein forming a tear in a portion of the packaging material includes extending a punch into a path of the dispensed packaging material.

3. The method of claim 1 , wherein identifying a first wrap force at which the tear exhibits a first behavior includes performing one or more wrap cycles, each at a different wrap force, until the first behavior is exhibited.

4. The method of claim 1 , wherein identifying a second wrap force at which the tear exhibits a second behavior includes performing one or more wrap cycles, each at a different wrap force, until the second behavior is exhibited.

5. The method of claim 1 , wherein selecting a first intermediate wrap force includes averaging the first wrap force and the second wrap force.

6. The method of claim 1 , wherein the first behavior is the beginning of the propagation of the tear in the packaging material.

7. The method of claim 1 , wherein the second behavior is the propagation of the tear to a rope or rolled cable of the packaging material.

8. The method of claim 1 , further comprising:

identifying a third wrap force at which the tear exhibits a third behavior; and

selecting a second intermediate wrap force between the second wrap force and the third wrap force.

9. The method of claim 8 , wherein the third behavior is the propagation of the tear to a rope or rolled cable of the packaging material, and the beginning of stretching of the rope or rolled cable.

10. A method for determining a payout percentage at which to wrap a load with packaging material, the method comprising:

dispensing packaging material to a load;

intentionally forming a tear in a portion of the packaging material;

identifying a first payout percentage at which the tear exhibits a first behavior;

identifying a second payout percentage at which the tear exhibits a second behavior; and

selecting a first intermediate payout percentage between the first payout percentage and the second payout percentage, for wrapping the load.

11. The method of claim 10 , wherein forming a tear in a portion of the packaging material includes extending a punch into a path of the dispensed packaging material.

12. The method of claim 10 , wherein identifying a first payout percentage at which the tear exhibits a first behavior includes performing one or more wrap cycles, each at a different payout percentage, until the first behavior is exhibited.

13. The method of claim 10 , wherein identifying a second payout percentage at which the tear exhibits a second behavior includes performing one or more wrap cycles, each at a different payout percentage, until the second behavior is exhibited.

14. The method of claim 10 , wherein selecting a first intermediate payout percentage includes averaging the first payout percentage and the second payout percentage.

15. The method of claim 10 , wherein the first behavior is the beginning of the propagation of the tear in the packaging material.

16. The method of claim 10 , wherein the second behavior is the propagation of the tear to a rope or rolled cable of the packaging material.

17. The method of claim 10 , further comprising:

identifying a third payout percentage at which the tear exhibits a third behavior; and

selecting a second intermediate payout percentage between the second payout percentage and the third payout percentage.

18. The method of claim 17 , wherein the third behavior is the propagation of the tear to a rope or rolled cable of the packaging material, and the beginning of stretching of the rope or rolled cable.

19. A method of determining a number of relative revolutions between a packaging material dispenser and a load for wrapping the load with a first packaging material, the method comprising:

wrapping a test load with the first packaging material at a selected wrap force setting;

determining an incremental force exerted by each wrap of the first packaging material on the test load;

determining a partial containment force for a wrapped load at a selected area of the wrapped load;

obtaining one or more characteristics of the load;

obtaining one or more characteristics of the first packaging material;

determining a total containment force for wrapping the load based on the partial containment force, the one or more characteristics of the load, and the one or more characteristics of the first packaging material; and

determining the number of relative revolutions for wrapping the load based on the total containment force and the wrap force exerted by each wrap of first packaging material on the test load.

20. The method of claim 19 , wherein obtaining one or more characteristics of the load includes obtaining a height of the load.

21. The method of claim 19 , wherein obtaining one or more characteristics of the first packaging material includes obtaining an effective height of the first packaging material.

22. The method of claim 19 , wherein determining a total containment force includes dividing a height of the load by an effective height of the first packaging material to obtain a first value.

23. The method of claim 22 , wherein determining a total containment force includes multiplying the first value by the wrap force exerted by each wrap of first packaging material on the test load.

24. The method of claim 19 , wherein wrapping the test load with the first packaging material at a selected wrap force setting includes wrapping the test load at a wrap force setting selected between a first wrap force setting at which a tear formed in the first packaging material exhibits a first behavior, and a second wrap force setting at which a tear formed in the first packaging material exhibits a second behavior.

25. The method of claim 24 , wherein:

the first behavior is the beginning of the propagation of the tear in the first packaging material; and

the second behavior is the propagation of the tear to a rope or rolled cable of the first packaging material.

26. The method of claim 19 , wherein determining the number of relative revolutions for wrapping the load includes dividing the total containment force by the wrap force exerted by each wrap of the first packaging material on the test load.

27. The method of claim 19 , further comprising:

determining a weight of packaging material for wrapping a load by:

determining a weight of each wrap of packaging material on the test load, and

determining the weight of packaging material for wrapping the load based on the number of revolutions and the weight of each wrap of packaging material on the test load.

28. The method of claim 19 , further comprising:

determining a number of relative revolutions between a packaging material dispenser and a load for wrapping the load with at least a second packaging material different from the first packaging material;

determining a weight of each of the first packaging material and the second packaging material by:

determining a weight of each wrap of packaging material on the test load, and

determining the weight of packaging material for wrapping the load based on the number of revolutions and the weight of each wrap of packaging material on the test load;

obtaining cost per weight values for each of the first packaging material and the second packaging material; and

determining packaging material costs for wrapping a load with each of the first packaging material and the second packaging material based on the cost per weight values and the determined weights for the first and second packaging materials.