System and method for forming protrusions in a substrate used to manufacture absorbent articles

A method of altering a portion of a substrate, comprising:

• providing a first device;
• providing a second device comprising a source of vibration energy;
• forming a nip between the source of vibration energy and the first device;
• conveying the substrate, through the nip;
• and
• altering a portion of the substrate, in the nip, to create a pattern of altered areas, wherein the altered areas have a pattern balance, and wherein the pattern balance comprises at least one of:
• a rate of change of an average area of the substrate altered in the nip being less than a threshold value across the portion of the substrate, wherein the threshold value of the rate of change of an average area of the substrate:
• is the difference between an average area between a first nip area and a second nip area, divided by the average area at the first nip area and multiplied by 100;
• and
• is between about −50% and about 50%;
• and
• a rate of change of a simple area of integral areas within the altered area being less than a threshold value across the portion of the substrate, wherein the threshold value of the rate of change of a simple area of integral areas is between about −20 mm2 and about 20 mm2.

A method of creating protrusions in a portion of a substrate, comprising:

• providing a first device;
• providing a second device comprising a source of vibration energy;
• forming a nip between the source of vibration energy and the first device;
• conveying the substrate, through the nip;
• creating the protrusions in a portion of the substrate in the nip to create an area of the protrusions;
• and
• flattening a portion of the area of the protrusions to create intermittent areas of the protrusions in the substrate.