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Die imbalance: An unbalanced die can result in the extrudate leaving the die at
varying speeds leading to deformation.
Co extrusion: The main challenge in the co extrusion process is to ensure a perfect
interface between the two materials.
Die Deformation: Die deformation takes place due to high internal pressure: this is
true while extruding wide and thin films.
All die surfaces must be free from defects otherwise unwanted patterns will appear
on the extruded product. Also overheating the melt is to be avoided at all costs, or the
product will not form properly on solidification. Once solid, the product material can
be wound, spun, or cut in defined lengths depending upon its intended end-use
USEFUL EXTRUSION CALCULATION
1) To calculate weight of film & bags
Film thickness is measured in Microns or gauge by dial guage
100 micron = 0.10 mm = 400 gauge
w = width of tubing in cms.
g = thickness of film in gauge weight in gms.
1. LDPE & LLDPE FILM = 0.48 x w x g
2. HDPE & HM HDPE = 0.50 x w x g
3. P. P. (TQPP) = 0.47 x w x g
4. Plasticised PVC (Transparent) = 0.68 x w x g
5. Rigid PVC film = 0.72 x w x g
2) Weight of bags in kgs. / 1000 bags =
Length in inches x width in inches x gauge
3300
3) Weight Of Polythene Film Roll Of 1000 Metres Length In Kilograms
THICKNESS
Standard Width of Films in In mms Microns
Gauge 25 30 40 50 60 75 100 125 175 200
Appx. 100 125 150 200 250 300 400 500 700 1000
Inches
1800 72 41.1 49.68 62.1 82.8 103.5 124.2 165.6 207 289.8 414
1500 60 34.5 41.4 51.75 69.0 86.25 103.5 138.0 172.5 241.5 345
1200 48 27.6 66.12 41.4 55.2 69.0 82.8 110.4 138 193.2 276
1100 44 25.3 30.36 37.92 50.6 63.1 75.84 101.2 126.2 176.8 253
100 40 23.0 27.6 34.5 46.0 57.5 69 92.0 115.0 161 230
900 36 20.7 24.84 31.05 41.4 51.75 62.1 82.8 103.5 114.9 207
600 24 13.8 16.56 20.7 27.6 34.5 41.4 52.2 69 96.6 138
500 20 11.5 13.8 16.56 23.0 28.75 39.5 46 57.5 80.5 115
300 12 6.9 8.28 10.35 13.8 17.25 20.7 27.6 34.5 48.3 69
250 10 5.75 6.9 8.62 11.5 14.37 19.75 23 28.75 40.25 57.5
DAVE TECHNICAL SERVICES 120
