Cransford Polythene Ltd.

Request a quote

Polythene Industry Tolerances.

Polythene film is manufactured by special extruder machines, the raw pellets are heated to 150°c or more until they become semi-liquefied at which point it is forced out of a circular die under pressure. The film is blown into a bubble and forms a vertical sausage shape that cools and is then rolled flat by counter rotating rollers at the top of the bubble.

The film then cools further and is wound onto a mother roll for converting into bags or to be sold as film on roll.

Bubbles, be they polythene or the type children blow with a detergent mixture are not the easiest of things to replicate let alone make them exactly the same size over and over again. A whole raft of variables will affect every batch, these include ambient and extruder temperature, polymer blend, machine speed, there are a lot of variables for the operator to factor in.

While every effort is made to make each batch the same it is inevitable they will be slightly different, we always aim for exact measurements but factors will at times mean this isn’t possible.

Width, +/- 3mm (0.125”) or 2% whichever is greater.

Length, +/- 6mm (0.25”) or 2% whichever is greater
Please note the length is measured cut to cut so with most end weld bags this includes the bottom skirt of approximately 8mm.

Material thickness, micron or gauge, +/- 10% of the target thickness.

Quantity, +/- 10% of the ordered quantity, this will vary for small batch orders and can be up to 20%.

It’s important to remember industry tolerances in order to make sure that your packaging will suit your product, and being aware that there may be very slight differences between batches.