Neither sealing motion is universally better
Rotary jaws travel continuously around a circular path and meet the film for a relatively short part of each revolution. Box-motion or long-dwell systems move the jaws with the film for a longer sealing contact before opening and returning. Manufacturer terminology and mechanical arrangements vary, so the proposed jaw motion, usable pack envelope and test conditions should be confirmed from the actual machine.
The correct choice is the one that produces an accepted seal with the selected film while clearing the product and supporting the required good-pack output. A nominal machine speed alone does not prove this.
Rotary-jaw considerations
Rotary motion is commonly assessed for regular products and films that seal within the available contact time. Continuous movement can support a compact, fast wrapping cycle, but product height, bag length, jaw diameter, cut position and film temperature window must work together.
Box-motion considerations
Longer contact may be useful for films or seal requirements that benefit from additional dwell and controlled pressure. The motion may also offer different clearance around taller packs. The trade-off can include a different mechanical cycle, footprint, complexity or maximum duty, depending on the machine. These are model-specific matters and should not be inferred from the term “box motion” alone.
Variables that should decide the comparison
- production film construction, sealant layer and verified sealing window;
- pack height, length, width and product clearance near the end seals;
- required seal appearance, strength and leak-test method where applicable;
- printed-film registration and permitted cut-position variation;
- product temperature, crumbs, moisture, dust or residue that may enter the seal;
- sustained good-pack output using the final infeed;
- format range, changeover and jaw access for cleaning or maintenance.