How to calculate what the weight of a specific spec product should be:

DIFFERENCES BETWEEN BLOWN AND CAST STRETCH FILMS

Differences Between Blown Blown Stretch Film And Cast Stretch Films

Differences between blown and cast stretch films is the process in which they are produced and manufactured. These differences also make a big impact on the usability of the film and its pricing. Cape Town affordable stretching film’s limits, different blown film and stretch films and pallet wrap film manufacturers.

Wrapping Machine Industry Standard Profiles

Wrapping Machine Industry Standard Profiles

FILM PROPERTIES BLOWN STRETCH FILM CAST STRETCH FILM
  Excellent holding properties in use. Will stretch after application so
LOAD RETENTION Will not stretch much further after application. palletised loads can be less stable.
       
  Good material memory to return    
FILM MEMORY to original size. Less material memory than blown fi lm.
       
  Has increased stretch and can wrap    
FILM YIELD more pallets with the same length. Not as much stretch as blown fi lm.
       
  Manufacturing process creates greater    
PUNCTURE RESISTANCE resistance to breakage of fi lm. Tearing can occur when fi lm is highly stressed
       
  1 sided cling, useful for higher load retention Can have cling on both sides that can cause
CLING OF FILM and prevents pallets sticking together in transit. pallets to stick together
       
  Not fully clear which can make barcode Perfectly clear, makes reading and scanning in
  scanning harder. However fi lm has lower warehouse light easy, but a higher gloss makes
VISUAL CLARITY gloss thus reducing refl ections. reflections which can reduce barcode read rates.
       
NOISE WHEN UNROLLED Can be very loud when releasing from the roll. Very quiet when unwound from the roll.

HOW TO CALCULATE WHAT THE WEIGHT OF A SPECIFIC SPEC PRODUCT SHOULD BE:

 

WIDTH

x

THICKNESS

x

LENGTH

x

SG

= WEIGHT

in meters

in millimetres

in meters

(specific gravity)

 

 

 

 

 

 

 

 

 

EXAMPLE: 450mm X 20µm X 1000m roll is 0.45 X 0.02 X 1000 X 0.92 = 8.28kg plastic.

 

The weight of the core should then be added for the total roll weight.

 

DIFFERENCES BETWEEN BLOWN AND CAST STRETCH FILMS

 

FILM PROPERTIES

BLOWN STRETCH FILM

CAST STRETCH FILM

 

Excellent holding properties in use.

Will stretch after application so

LOAD RETENTION

Will not stretch much further after application.

palletised loads can be less stable.

 

 

 

 

 

Good material memory to return

 

 

FILM MEMORY

to original size.

Less material memory than blown fi lm.

 

 

 

 

 

Has increased stretch and can wrap

 

 

FILM YIELD

more pallets with the same length.

Not as much stretch as blown fi lm.

 

 

 

 

 

Manufacturing process creates greater

 

 

PUNCTURE RESISTANCE

resistance to breakage of fi lm.

Tearing can occur when fi lm is highly stressed

 

 

 

 

 

1 sided cling, useful for higher load retention

Can have cling on both sides that can cause

CLING OF FILM

and prevents pallets sticking together in transit.

pallets to stick together

 

 

 

 

 

Not fully clear which can make barcode

Perfectly clear, makes reading and scanning in

 

scanning harder. However fi lm has lower

warehouse light easy, but a higher gloss makes

VISUAL CLARITY

gloss thus reducing refl ections.

reflections which can reduce barcode read rates.

 

 

 

 

NOISE WHEN UNROLLED

Can be very loud when releasing from the roll.

Very quiet when unwound from the roll.

 

 

 

 

 

Referenced from Optimisation of pallet wrapping film use (https://www.slideshare.net/BobGiles/pallet-optimisation-64943165)

 

WRAPPING MACHINE INDUSTRY STANDARD PROFILES

 

 

 

 

 

 

A PROFILE

 

A pallet load with load footprint the same size as the pallet, with uniform shape and no protrusions.

 

 

 

 

 

 

B PROFILE

 

A pallet load with load footprint different to the size of the pallet with the load slightly irregular shaped.

 

 

 

 

 

 

C PROFILE

 

A pallet load where the load footprint is significantly different to the size of the pallet and the load is highly irregular with many sharp edges or protrusions.

 

CRITERIA

MANUAL WRAPPING

SEMI-AUTOMATIC

FULLY AUTOMATED

 

 

 

 

 

 

Cost effective in most throughputs

 

Throughput

Limited by ability of labour

greater than 100 pallets per day

Requires large throughput

 

 

 

 

PROFILE A

Suitable

Suitable

Suitable

 

 

 

 

PROFILE B

Suitable

Suitable

Suitable

 

 

 

 

PROFILE C

Suitable

Not Recommended

Not Recommended

 

 

 

 

Flexibility

Highly Flexible

Flexible

Infl exible

 

 

 

 

Consistency of

Wrapping pattern

 

 

application

dependant on operator

High

High

 

 

 

 

Film damage & Waste

High

Low

Low

 

 

 

 

 

Referenced from Optimisation of pallet wrapping film use (https://www.slideshare.net/BobGiles/pallet-optimisation-64943165)

 

MULTI-LAYER CAST MATERIAL

 

The assumption that a high number of layers in multi layered fi lms makes it stronger, is incorrect. The importance rests on what is put inside the layers rather than the number of layers. Coextruding layers with a single polymer increases the throughput of the production, but does not affect the properties.

 

Read more on multi-layer cast material: http://www.ptonline.com/articles/stretching-film’s-limits.

Semi-Automatic machine criteria