How to Read a Stretch Film Data Sheet

A stretch film data sheet is a short document, and every line on it changes something on your wrapping line. Here is what each one is telling you.

Length And Width

How much film is on the roll and how wide the web is. Together they give you the area on the roll, which is where any cost per pallet calculation starts. Width also decides how many passes it takes to cover a load height.

Average Thickness

Measured before stretching. The applied film on a pallet is thinner than the sheet figure because it has been elongated. This is why comparing two films on thickness alone is misleading if one is prestretched and the other is not.

Prestretch

How far the film is elongated. On a prestretchable grade this happens on your wrapper, so it is a machine setting. On a prestretched grade it happens in production, so the film arrives at its final dimensions. A prestretch figure of 230 percent means one metre of film covers far more than one metre of pallet face.

Elongation At Break

The point at which the film fails. The relationship between this and the prestretch figure is the most useful thing on the sheet. JMSH01 is prestretched to 230 percent with a break at 250 percent, a working margin. JMSH02 is prestretched to 50 percent with a break at 55 percent, a much narrower margin because most of the stretch has already been used.

Tensile Stress At Break

The pulling force the web takes before it parts, quoted in kilograms. This is the number that most closely tracks how heavy and irregular a load the film will hold. JMSH01 is 26 kg. JMSH02 is 15 kg.

Number Of Holes

On a ventilated film, the perforation count across the web. Both Jiamei grades carry thirteen. This is what separates a ventilated film from a solid one of the same gauge.

Weight Per Metre And Weight Per Roll

Weight per metre converts directly into plastic per pallet once you know your pass count and prestretch. Weight per roll tells you what an operator has to lift and how long a roll lasts. A 440 m manual roll at 1.37 kg is a different object from an 11 kg machine roll.

Tolerances

The most under used column. Width to five percent, thickness to two microns and weight per metre to five percent give your goods inwards team a concrete check. If a delivery is outside those figures it will not behave like the sample you approved, and you have a basis for saying so.

Reading Two Sheets Side By Side

A Short Checklist For A New Supplier

1. Does the sheet quote tolerances as well as nominal values?
2. Is the prestretch figure a machine setting or already applied?
3. What is the gap between prestretch and elongation at break?
4. What is the tensile stress at break, and does it suit your heaviest load?
5. What does one metre weigh, and what does that mean per pallet at your pass count?
6. Which roll formats exist, and do they run on your wrapper and your mandrel?