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Shrink film used to be the norm before stretch wrap was invented. Most goods these days are stretch wrapped as the cost is lower and it takes very little time to complete the task, plus is does away with using an open flame.
Shrink film is available in perforated bag on a roil form of different heights, according to your load height (remember to add another 600 mm for the top overlap and another 200 mm if capturing the pallet also).
Various film gauges are available, but they need to be 100um minimum. The reason being that as you apply heat, the film shrinks as it absorbs the heat. Thin film can ignite easily.
The secret is NEVER to keep heat in one place. It is necessary to keep the gas gun moving at all times. You will have to move over the same spot many times, putting a little heat into it every time. A broad brush movement, as you move around the pallet is the answer to uniform shrink wrapping.
You will see the film change from limp to taught as the flame hits it. The aim is to pull taught broad swathes, rather than linger in one spot.
If you are capturing the load to the pallet, then allow excess film to fall below the pallet, and have the load pallet sitting on one or more pallets that are not square to the load pallet, so that the corners of the load pallet are exposed.
Using your hardwood stick (you can wet it if you prefer), push the corners under the pallet, then apply heat to seal the flaps together. If you shrink the body of the load first, the corners will rise up past the pallet. Optionally, you can fold the plastic under the pallet corner then staple them before applying heat.
Shrink film also comes as a perforated or continuous gusset on a roll, The gusset allows the roll to present no longer than 1200 mm wide. Unfolding it, presents as a square of 1200 mm.
If on a continuous roll, you will need to seal the top cut end. Pulling the amount you need off the roll, cut, then lay it down on a clean floor, find a hardwood beam and lay it 50 mm below the top edge. This prevents the various edges from moving apart, as they cannot move past the wooden bar. Using your gas gun, spread the flame between the folds, using a stick of hardwood, to push the various layers together until they seal as one line. Be careful not to touch the hot melted plastic. Wait a few moments until it cools, before you check for seal integrity.
Optionally, you can spread the film out to its full width and seal the top edge that way. Each has its merits.
Gas guns are supplied with or without the necessary hose and regulator. The gas bottle is the same type as used with your barbeque. Your local gas supplier can also supply you with hoses (pick a long one, to save you moving the gas bottle around). Ask for the appropriate fittings, regulator, blow back valve, pressure gauge – as required. Tell them what you need it for, as they may recommend a hose spiral covering to prevent wear and tear, or a sturdier hose. It is also a good idea to have a spare gas bottle on hand for when that first one runs out – usually mid wrap!
REMEMBER, that you are dealing with a powerful open flame, so provide personal protection such as welders gloves, safety goggles, long pants, appropriate footwear, etc., along with a tested fire extinguisher.
Also be aware to keep others away from the area you are working in by erecting a portable barrier, with a warning sign: DO NOT ENTER – OPEN FLAME AREA. Never use in a confined space and where fumes from chemicals can start a blaze or where litter can catch fire.
People have been burnt as an operator inadvertently swung around a gas gun to greet a visitor, or his phone has rung and he has forgotten to turn off the gas gun that is still playing on the load.
Film can catch fire, so have a watered rag on hand to instantly smother the area. If an area of film is holed, you can patch it up using a large oversized section of film to cover the hole then gently seal the hole edges.
Goods and factories can catch fire, so be aware and very careful about using gas guns. If unsure, please talk to us about the job and possible options.Get In Touch