Shrink Wrapping vs Stretch Wrapping for ASEAN Packing Lines: Heat, Humidity and Containment Force

Shrink or Stretch? Usually You Need Both

Shrink wrapping and stretch wrapping are not two ways of doing the same job. Shrink film bundles the **sales pack or multipack** and needs a heated tunnel at 130–170 °C. Stretch film unitises the **pallet**, cold, with no heat at all. The only place a genuine either/or exists is at pallet level — shrink hooding versus stretch wrapping or stretch hooding — and there stretch wins on running cost precisely because nothing is heated.

For an ASEAN packing line, two numbers decide the project:

1. **The shrink tunnel, not the sealer, is the electrical load.** On a full-servo shrink packer we list, the packing machine draws 4.75 kW while its shrink tunnel draws 13.5 kW — the tunnel is roughly three quarters of the connected load. 2. **Stretch film containment force must be specified at arrival, not at the wrapper.** Published 30-day testing on 20.3-micron machine films measured an average **41% containment loss at 38 °C against 26% at 23 °C** — and 38 °C is a normal afternoon inside an ASEAN warehouse or a dry container.

Two Different Jobs in One Line

| Level | Method | Heat? | What it is actually for | |---|---|---|---| | Primary / multipack | Shrink film (POF, PVC, PE) | Yes, 130–170 °C tunnel | Retail bundle, tamper evidence, print display, dust seal | | Unit load (pallet) | Stretch film, spiral wrapped | No | Holding cartons to each other and to the pallet in transit | | Unit load (pallet) | Shrink hood | Yes, gas or electric shrink frame | Weather protection plus containment, outdoor storage | | Unit load (pallet) | Strapping | No | Compressing rigid, heavy or slippery loads |

Most enquiries that arrive as "shrink or stretch" are really two purchases: a shrink bundler for the pack, and a pallet wrapper or strapper at the end of the line. A [strapping machine](/en/products/chengyi-intelligent-packaging-equipment-cy-101a-fully-automatic-strapping-machine) at 1.0 kW and ≤2.5 seconds per strap is a different order of cost from a 13.5 kW tunnel, and for dense rigid loads it often does more for stability per baht spent.

Where the Real Either/Or Is

At pallet level the comparison is consistent across industry sources: heat shrink hooding costs more to run than both spiral stretch wrapping and stretch hooding, because the film must be heated and because a shrink bag has to be larger than the load perimeter before shrinking, consuming more material. Shrink hooding earns its place where loads sit outdoors or travel uncovered; inside a factory-to-container flow — most ASEAN export packing — stretch is the default.

Why the Tropics Change the Answer

Film Relaxes When It Is Hot

Containment force is not a constant. It decays after wrapping, and faster when warm. In the 30-day study above, most of the loss happened in the **first two hours** at 23 °C, while the high-performance film at 38 °C kept relaxing for **seven days**. So a load that measures correctly in an air-conditioned QC room can reach the port meaningfully looser. Verify containment force on a load that has sat in ambient conditions, not on one straight off the turntable.

Cartons Get Weaker When It Is Humid

Corrugated board loses compression strength with moisture. Published strength-retention curves put a box at roughly **68% of its rated compression strength at 80% RH** — about a third gone — and a swing from 40% to 90% RH can cost around half the stack strength. ASEAN ambient humidity sits in exactly that band for most of the year.

Put the two together and you get the tropical squeeze: **the film is asked to carry more of the load exactly when it holds less.** This is why a wrap pattern copied from a temperate-climate parent plant tends to fail here, and why pallet-level containment and [rack load assumptions](/en/news/pallet-racking-selection-asean-warehouse) need to be revisited together rather than separately.

The Shrink Tunnel Is the Cost Centre

Real specifications from machines we list, as published on their product pages:

| Machine | Throughput | Power | Note | |---|---|---|---| | [Full-servo high-speed shrink packer](/en/products/chengyi-intelligent-packaging-equipment-cy-590-full-servo-high-speed-shrink-packaging-machine) | 30–150 pcs/min | 4.75 kW packer **+ 13.5 kW tunnel** | Thin/flat products: L 60–320, W 10–200, H 5–35 mm; film ≤590 mm | | [High-speed sealer + tunnel line](/en/products/ali-store-10-80-packs-min-automatic-high-speed-sealing-shrink-packaging-machine) | 10–80 packs/min | 13.5 kW total | Max pack 500 × 400 × 125 mm; 380 V 3-phase; air ≤0.5 MPa; 600 + 600 kg | | [Side-sealing shrink wrapper](/en/products/ali-store-automatic-eco-friendly-side-sealing-shrink-wrapping-machine-for-bottled-water-ju) | 50 packs/min | 220 V supply | 530 kg, 1800 × 940 × 1670 mm; product 100–500 × 5–320 × 5–180 mm |

Three things buyers routinely miss in that table:

• **Supply type differs by machine.** One needs 380 V three-phase, another runs on 220 V. Confirm phase, frequency and breaker size against your actual plant supply before signing, not after the crate lands.
• **Compressed air is a separate utility.** A sealer specified at ≤0.5 MPa still needs a compressor sized for it — a second capital line item.
• **The tunnel's heat goes into your building.** 13.5 kW of nameplate heating is about 46,000 BTU/h — roughly 3.8 tons of refrigeration — if the line sits in conditioned space. That is arithmetic on the nameplate at full duty rather than a measured figure, and real duty cycle is lower; but it is the right order of magnitude to hand to whoever is [sizing your chiller](/en/news/industrial-chiller-sizing-tropical-asean). Vent the tunnel outside where the layout allows.

Choose the Film Before You Choose the Machine

Shrink tunnels are commissioned around one film family, and the ranges do not overlap cleanly: **PVC 130–160 °C, POF 140–150 °C, PE 140–170 °C**. A machine set up and accepted on PVC will not simply run PE at the same settings.

Film choice is increasingly a compliance question, not only a cost one:

• **POF is the default for food contact.** PVC releases irritant fumes when heated and is widely avoided for food packaging; POF formulations are made for direct contact and give better clarity. If you pack food, specify POF in the contract and require the supplier's food-contact documentation — the same evidence discipline as for [vacuum packaging film](/en/news/vacuum-packaging-seafood-export-asean).
• **Regional plastics policy is tightening.** Thailand's Plastic Waste Management Action Plan Phase II (2023–2027) sets out EPR for plastic packaging with a 30% producer waste-reduction target by 2029; Indonesia announced in August 2025 an intention to mandate EPR by 2029 alongside a single-use plastics ban targeted for end-2026. These are roadmaps and announced intentions, not settled obligations on industrial transport packaging — check the current position with local counsel before assuming your film qualifies.

Buying Notes and Common Pitfalls

• **"Meets ASTM D4649" means very little.** D4649 is a *guide* for selecting and using stretch films, its own annex test methods are explicitly not ASTM standards, and no containment-force tool is ASTM-approved. Ask for measured containment force, film gauge, pre-stretch setting and wrap pattern instead of a standard number.
• **Pre-stretch is where film cost is won.** Machine film run at 200–300% pre-stretch cuts applied film per pallet substantially — vendors cite about 600 m dropping to 300 m on a 30-wrap pallet at 200% — but yield claims come from film sellers, so validate on your own loads and wrapper.
• **Do not buy tunnel width for a product you do not run.** Film width caps pack size (≤590 mm and 630 mm above). Oversized tunnels burn energy on air.
• **Write the acceptance test into the PO:** throughput at your pack size, seal quality after a full shift at line temperature, measured power draw, and — for pallet wrapping — containment force measured on a load conditioned at ambient.
• **Spare parts are the long-term cost.** Sealing knives, Teflon belts and heating elements are consumables on a tropical duty cycle. Price them with the machine.

Conclusion

Treat shrink and stretch as two decisions, not one. Budget the tunnel's electricity and heat rejection honestly, pick the film family before the machine, and specify pallet containment force on a load that has already sat in the heat. Browse [shrink wrapping machines](/en/products?category=pm-shrink-wrapping) for current models, see [our China sourcing service](/en/china-sourcing) if you want factory verification and consolidation handled, or [contact us](/en/contact) with your pack dimensions, throughput and plant supply for matched options.