Technical Details

The following gives the various shrink ratios available. These are often dependant upon the blow-up ratio achieved when producing the film and the actual width of the end product. The most popular shrink is SBZ for SWS and SCY for CFS. It is almost impossible to supply a film with the characteristic of SDW due to the nature of the production process. Most films can be supplied either High or Low slip

Shrink in Transverse Direction Shrink in Machine Direction Slip Level
SA - Less than 10%
SB - 10%-20%
SC - 20%-35%
SD - 35% and above
W - Less than 40%
X - 40%-50%
Y - 50%-60%
Z - 60% and above
EL - Extra Low
N - Normal
H - High Slip
E. G. Shrink Film coded SBZEL would have 10%-20% shrink in Transverse Direction 60% and above shrink in Machine Direction and Extra Low Slip.

 

Property

Most films without additives give a reasonable clarity but, as the thickness increases, the clarity decreases. Where a high clarity thin film is used, the packaged property can be clearly seen. The clarity is also affected by any additives, such as Linear LDPE, which will reduce the clarity. Also, if coloured film is required, the thicker the film then a better opacity of film can be achieved. It is virtually impossible to obtain a 25micron film that is totally opaque.

Films are mainly supplied as either Low or High Slip. High slip film is more suitable to films that require easy opening for packaging such as produce bags. Low slip films are often used in shrink or other applications where the product needs to be palletised or stacked with stability is a safety requirement. It is recommended that the customer ensures the correct slip level of film required before ordering.

 

Yield and Sizing

The table below gives an indication of the film yield for various thickness of material. Any other thickness can be calculated on a pro-rata basis.

The second table enables the actual weight of film required for each pack. This is a useful tool to use when calculating the actual cost of the film used for each pack.

Prices are available for all our products on request.

Should you have any questions or require further information please phone 0161 428 4251 (fax 8329) or e-mail trevor@polythene-films.com.

Thickness
Mu

25
30
40
50
60
Yield
M²/KG

43.38
36.15
27.15
21.69
18.08
Thickness
Mu

70
80
90
100
120
Yield
M²/KG

15.49
13.56
12.05
10.85
9.04
Thickness
Mu

150
180
200
250
Yield
M²/KG

7.23
6.03
5.42
4.34

PACK SIZING:
Use the following methods to
determine the film size needed
for your pack.

A WIDTH
B LENGTH
C HEIGHT

Sleeve-Wrap Packing using Sheet Film
WIDTH OF FILM= A + ¾C
LENGTH OF WRAP= 2(B+C) + 10% Shrink Allowance
TOTAL FILM USE PER PACK (kg)=
Width of Film (M) x Length of Wrap (M)
Yield (M²/Kg)


Overwrap Packing using Centre-Fold Film

WIDTH OF FILM = (A+C) + 10% Shrink Allowance
(This gives Centre-Fold Width)
LENGTH OF WRAP= (B+C) + 10% Shrink Allowance
TOTAL FILM USE PER PACK (kg)=

2 x Centre-Fold Width (M) + Length of Wrap (M)
Yield (M²/Kg)
Film cost per pack - Film used per pack (KG) x Price (Pence/Kg)

 

 





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