VFFS motion comparison
The motion system changes how film is advanced, how the horizontal seal is made and how much time is available for product dosing and sealing. Select the route from the real product, bag, film and accepted-output requirement rather than from a catalogue speed alone.
Buyer guidance
Intermittent machines stop the film while the cross-seal jaws close. Continuous or box-motion systems move the jaws with the film for part of the cycle. Either architecture can be appropriate; the decision depends on product fall time, bag length, seal dwell, film behaviour, required output and the connected dosing and inspection equipment.
In an intermittent cycle the film indexes by the programmed bag length and then stops. The horizontal jaws close to make the top seal of one bag and the bottom seal of the next before the film advances again. The stopped web creates a clear period for sealing and cutting, which can simplify setup for varied bag lengths, slower dosing cycles and applications where the required accepted output does not justify a continuous-motion platform.
A continuous-motion system keeps the film moving while the horizontal jaws travel with it during the sealing phase. The relative movement between jaw and film is controlled so pressure and heat can be applied while the web continues through the machine. This can reduce the stop-start limitation of the film path, but it places greater importance on synchronisation between dosing, film transport, jaw motion, registration, discharge and downstream handling.
The bagger cannot seal until product has cleared the seal area. Powders may need time for the dose to settle and for airborne product to clear; granules may bounce or bridge; fragile pieces may require a controlled drop; liquids and pastes need nozzle shut-off and drip control. Measure the complete dose-and-clear cycle with representative product. A faster film motion cannot compensate for a dosing system that has not finished cleanly.
Seal performance depends on the film construction, sealant layer, jaw temperature, pressure, contact time, cooling and contamination. Longer bags also change the film index or jaw travel required. Printed film adds a registration requirement. Confirm the intended film reel, repeat length, vertical-seal style, horizontal-seal width, cut position and any tear notch or hole punch during the trial rather than assuming that the motion type alone determines quality.
Compare the number of packs that meet the agreed dose, dimensions, registration, seal, cut and coding checks while the whole line is running. Record start-up waste, planned stops, reel changes, product refill events, rejected packs and downstream interruptions. This separates genuine production benefit from a peak cycle count measured without the real product and connected equipment.
Decision aid
| Selection factor | Intermittent motion: questions to test | Continuous or box motion: questions to test |
|---|---|---|
| Product dosing | Does the dose complete and clear the seal area within the stopped-web cycle? | Can dosing remain synchronised while the web and jaws continue to move? |
| Film and seal | Is the available stationary dwell suitable for the chosen film and seal width? | Can travelling-jaw contact produce a repeatable seal on the actual film? |
| Bag format | Are the required bag lengths and changeovers practical within the index range? | Does jaw travel and control suit the intended bag length and repeat? |
| Accepted output | Does the complete line meet the saleable-pack target with normal stops? | Does higher motion capability still deliver accepted packs after inspection and discharge? |
| Maintenance and skills | Can operators set index, jaw and registration parameters consistently? | Are motion control, synchronisation and specialist maintenance supported? |
Quotation preparation
Buyer questions
It can remove part of the stop-start limitation, but accepted output still depends on dosing, product clearance, sealing, registration, inspection and downstream handling.
No. Suitability depends on the application and machine design. The useful comparison is repeatable accepted output with the real product and film.
Possibly, but sealing behaviour, friction, tracking and contact time must be checked on the proposed machine configuration.
Record dose completion, product clearance, bag dimensions, registration, seal integrity, cut position, coding, rejects, stops and saleable output.
No. Augers, weighers, volumetric systems and pumps are selected around the product; their cycle must then be coordinated with the bagger motion.
Application review