Heat-shrink vs stretch wrapping: the energy and film maths

Most shrink-versus-stretch comparisons stop at the roll price, the one number that settles nothing. Wrapping a pack or a pallet costs three things: the energy to run the process, the material that ends up on the load, and the minutes of machine and operator time it takes. Change the method and all three move. What follows uses the published figures for Toreto's pack-wrapping machinery and the measurements from Toreto's own wrap tests; you supply the electricity tariff and the wage.

Heat-shrink needs a tunnel held above the film's shrink temperature for as long as the line runs. Cold stretch wrapping needs a motor and a film carriage. The published figures for the AW12 and AW24 systems put the draw at around 2 kW against roughly 15 kW for the heat-shrink line they replace: about 86.7% less. The figures are indicative and confirmed at quotation.

The arithmetic is yours to finish. Take the difference — roughly 13 kW — and multiply it by what you pay per kilowatt-hour and by the hours the tunnel is hot. Use the hours it is hot, not the hours it is producing. A tunnel that must be at temperature before the first pack, and stays there through breaks and changeovers, spends much of its day drawing power with nothing inside it.

That is where the warm-up shows up twice: once as energy nobody packed anything with, and once as the half hour at the start of a shift when the line cannot run. A cold wrapper starts when the operator does.

Shrink film is specified for what it has to survive. It must hold its shape through the heat, shrink evenly rather than tearing at the corners, and come out of the tunnel with enough body left to protect the pack. Those requirements put a floor under the gauge before anyone has thought about containment.

Stretch film gets its holding force from elongation and cling instead, so the same result can be built from far less material. On the pack wrappers the published figure is around 50% less film than heat-shrink, again indicative. That halving is material on the pack, and it repeats on every pack, every shift, for the life of the machine.

The pallet end of the operation shows the same effect, measured rather than estimated. In August 2026 Toreto ran the same pallet on the same machine at the same power stretch and tension settings, weighed the film off each wrap and measured how hard it held. Solid 23µ film at 250% held 9.9 kg/sq in using 200 g of plastic, at about €0.48 a pallet.

Reinforced 16µ Supersonic — and Aerosonic, its perforated twin, built from the same materials — held 10 kg/sq in on 66 g, at about €0.32. More containment, a third of the plastic. These are Toreto's own measurements, and the cost per pallet moves with film price and pallet size.

The line that matters for a machinery decision is the one about revolutions. The reinforced films went on in roughly half the revolutions of the solid film, so the wrapper spent about half as long on each pallet. Same machine, same shift, about twice as many pallets out of it. Film specification is a throughput decision, not only a purchasing one.

Machine time and operator time rarely appear in a film comparison, and they are usually the largest line in it. Toreto measured that too, in the United Kingdom in August 2026, on a pallet that had arrived machine-wrapped with several film failures. The film was cut off and weighed: 181 g, £0.60 of film, two minutes of labour at £0.20 a minute — £1.00 to wrap that pallet.

Rewrapped by hand from the Hyper Wrap System dispenser, the same pallet took 151 g, £0.54 of film and one minute of labour: £0.74. That is 26% off the cost, in half the time. Be precise about where the saving sits — 50% fewer metres went onto the load, because the film is stronger and wider, while the weight fell only from 181 g to 151 g.

Half the wrap time is either twice the pallets per shift or the same pallets with fewer people on the job. Either way it lands in the labour line rather than the film line, which is exactly why a comparison built on roll price alone gets the answer wrong.

None of this makes the tunnel obsolete. If the sealed skin is part of the product — a printed shrink sleeve, a tamper-evident pack conformed to an awkward shape, a pack that has to keep water out on its own — heat does something stretch film does not. Replace it there and you have removed the thing the customer was paying for.

The useful question is narrower than shrink versus stretch. It is whether, on this pack and this line, the tunnel earns the heat, the warm-up and the floor space. On plenty of trayed and bundled goods the answer is no, and it has been no for years without anyone doing the sum.

It takes an afternoon. Weigh the film off one finished pack and one finished pallet, so you argue in grams, not opinions. Take the tunnel's rating and log the hours it is hot, not the hours it produces. Price labour by the minute, the way Toreto's field test did. Then run the same pack both ways and compare the totals, not the roll prices. If the tunnel draws for hours it never packs in, they will not be close.