Flow wrapping forms a continuous tube of film around the product and fuses it shut with heat-sealed seams; overwrapping folds a sheet of film around a rigid product and tacks the folds down with heated plates. The first gives you a sealed, often airtight pillow pack at high speed on almost any product shape. The second gives you a tight, carton-like wrap on flat, straight-edged items at a fraction of that speed, and only when the product or its box is stiff enough to fold against.
That is the whole decision in one line: if the film is the primary pack, flow wrap; if a carton is already the primary pack and the film is there for finish and tamper evidence, overwrap. Shrink wrapping covers the shapes neither handles.
Flow wrapping is horizontal form-fill-seal. Film runs off a single roll and is formed into a tube around products moving along an infeed conveyor; a pair of heated wheels seals the tube lengthwise, and rotating cross-seal jaws seal and cut between one product and the next. What comes off the discharge is a pillow pack — a fin seal down the back and a crimped seal at each end.
A common horizontal flow wrapper runs 50 to 150 packs a minute; high-speed machines reach 300 or more. The rated figure assumes products arriving flat and at a steady pitch. A product that rolls, stands tall, or arrives in clumps drops the real number well below the nameplate, because the cross-seal jaws have to close in the gap between products, not on them.
The long seal is a fin seal by default. A lap seal, where the film edges overlap flat against the product, needs film that seals on both faces, and most flow wrappers cannot make one — treat it as an option to confirm, not a given.
Overwrapping wraps a rigid product in a sheet of film by pushing the product through the film, folding the film around it, and pressing the folds closed with heated plates. There is no tube and no crimped seal: the film folds like a parcel — an overlap along the base, envelope folds at the ends — and heat only tacks the overlaps down. The result is the tight, square wrap on a cigarette pack, a tea carton or a perfume box, usually with a tear tape for opening.
Because the machine folds against the product’s edges, it needs flat, straight-edged items — cartons, boxes, lidded trays — and it is almost always a secondary layer over a primary pack rather than the primary pack itself. Films are heat-sealable BOPP or paper-based alternatives.
Speed depends on how many formats the machine has to handle. A general-purpose fully automatic carton overwrapper runs up to about 60 packs a minute. Dedicated single-format machines built for cigarette packs run 630 to 1,000 packs a minute — faster than most flow wrappers — but only because they do one pack size and nothing else. For a tea, cosmetics or confectionery line that changes carton sizes, the 60-a-minute class is the realistic comparison.
The two methods differ in how the film closes, and every other row in the table follows from that: fused seals give flow wrapping its barrier, its speed and its tolerance for shape; folded overlaps give overwrapping its carton-grade finish and its limits.
| Feature | Flow Wrapping | Overwrapping |
|---|---|---|
| Basic process | Continuous form-fill-seal | Film folded around product |
| Typical machine | Horizontal flow wrapper | Overwrapping machine |
| Film supply | Continuous roll | Roll-fed or cut film |
| Package shape | Pillow-style pack | Neat folded wrap |
| Longitudinal seal | Fin seal (lap seal on some machines and films) | Folded overlap |
| End closure | Heat-sealed cross seals | Folded and/or heat-sealed |
| Product protection | High | Moderate to high |
| Airtight package | Often possible | Usually less suitable |
| Packaging speed | Very high | Moderate on general-purpose machines; very high on single-format machines |
| Appearance | Functional, modern | Premium, carton-like |
| Irregular products | Generally more flexible | Best with regular shapes |
| Common products | Food, bakery, bars, hardware | Cartons, cosmetics, cigarettes, tea |
| Tamper evidence | Yes — a heat-sealed pouch whose seams cannot be resealed | Common, but only with a tight fit and non-resealable folds |
Airtight is the row that matters most for food. A fin seal and two cross seals are fused film to film, so a flow-wrapped pack can hold a gas flush; an overwrap’s end folds are tacked, not fused, and air moves through them freely. Overwrapping is a dust-and-presentation layer, not a barrier.
A torn overwrap is the tamper-evidence format consumers recognise, but a folded wrap is not tamper-evident by itself. The FDA’s compliance guide for OTC drug packaging accepts a film wrapper only if it fits tightly and its overlapping end flaps cannot be opened and resealed without visible evidence; cellophane with overlapping end flaps it names as not effective.
Shrink wrapping is the option for the shapes the other two refuse. The product is loosely sealed in polyolefin, polyethylene or PVC film and passed through a heat tunnel, where the film shrinks tight to whatever is inside, irregular edges and sharp corners included.
What you give up is the seal and the finish. A shrink pack is tight but not airtight — the film has to vent as it shrinks, and the seams stay visible — so it is neither a barrier pack nor a carton-quality wrap. It also holds the product at tunnel heat for the length of the tunnel, which rules it out for chocolate and anything else that softens.
Where it beats both is bundling — a multipack of cartons, a tray of cans — and giving a rigid container the tight fit that makes a film wrapper tamper-evident; the FDA guide’s own example of how to get that fit is a shrink-type process.
Choose by what the film has to do for the product.
The choice also fixes what stands beside the machine. An overwrapper needs the carton to fold against, so it only ever stands downstream of a cartoner; on a line that is not yet cartoning, it is the second machine you buy, not the first.
Flow wrapping seals; overwrapping folds. That one mechanical difference gives flow wrapping the barrier, the speed on machines you can buy for a mixed line, and the tolerance for odd shapes, and gives overwrapping the carton-grade finish on products that already have a box. Decide by what the film must do for the product, then size the machine to the packs a minute your infeed can actually hold.
