Strapping is a common packaging method which is widely used in goods handling and transportation. It is used as a protective packaging method and for securing goods and pallet loads.
Strapping and banding are commonly used as packaging means, why?
Strapping Machines can generally be divided into two categories:
These machines can apply either a vertical or a horizontal strap around a pack or pallet. In some cases, packs or pallets are strapped vertically as well as horizontally.
Machines to strap individual packs are available in semi-automatic, automatic or automated versions. They generally run Polypropylene strap from 5mm to 12mm. Semi-Automatics are stand-alone machines and the operator feeds the strap manually into the machine and operates the start button to strap the pack. In the case of Automatic and Automated machines, the package is placed inside an arch and the strap is then fed around an arch and applied to the pack automatically. With Automatic machines, the operator places the package inside the arch, whereas with Automated machines the pack is indexed into the arch by a conveyor.
Pallet Strapping machines, which could be stand-alone or integrated into a packaging line feed the strap around an arch and apply it to the pack automatically. They generally run Polypropylene strap (PP) from 5mm to 12mm or Polyester Strap (PET) from 9mm to 16mm.
Manual and Battery Operated Hand Tools are also available for low volume usage.
Nowadays most strap is produced using PP or PET (both of which are both recyclable), however this has only been the case from the 1990’s. Before plastic strap became available from the 1960’s onwards, Woven Strap or Steel strap were the main materials used to strap packs or pallets.
Woven Strap is generally made from polyester or rayon yarns woven together and bonded in a hot melt process, and is sometimes referred to as corded strapping. Woven strap is usually applied by hand using buckles to tension it to the pack, and is mainly used where lighter tension is required.
For high tension applications such as bricks, concrete blocks, timber and tiles, steel strap used to be the material of choice, however since the 1990’s Steel has been largely superseded by PET. The advantages of PET compared to Steel are as follows:
PP Strap is generally made from virgin polymer (although some manufactures add regrind which can lead to issues with splitting) and is available in a variety of colours. Commonly available widths are 5mm, 6.5mm, 9mm, 12mm, and the strap is usually embossed. High Elongation PP (typically 25-35%), which renders the strap less stiff, is useful for smaller packs especially with sharp corners).
PET used to be made from virgin polymer, but over the last 10 years the trend has been towards using recycled PET bottles to make PET strap hence it is often referred to as RPET. Commonly available widths are 9mm, 12mm, 15.5mm, 16mm, and the strap is available either in smooth or embossed variants. PET strap is generally green in colour.
As well as being available in different widths and gauges, plastic strap is available with different breaking strengths according to whether a lighter or a heavier tension is required. When selecting the right strap, it is important to know the dimensions and weight of the pack and how it will be stored and transported.
Some companies purchase pre-printed strap either to enhance company branding or to comply with traceability regulations. Alternatively it is possible to print in-line directly onto the strap meaning that dates and batch codes can easily and quickly be entered into the printer.