Film and Sheet Extrusion

Metallurgy and materials Engineering, University of Punjab, Lahore

1. Film and sheet extrusion Muhammad Ahmad 14-MME-S1-309 Metallurgical & materials engineering

2. Introduction Extrusion the forcing of a plastic or molten material through a shaped die by means of pressure . The most common product form is thin film, either flat or tubular. Other extruded products include pipe and tubing, coated paper or foil, monofilaments and textile fibers, flat sheet (anything over 0.010 inch (0.25 mm)), wire and cable covering, and a great variety of profiles such as window frames, gaskets, channels and house siding. The products can be cut to length or rolled up as needed.

3. Raw materials Standard materials extruded are Nylon (6 & 66 & MDS), Acetyl, HDPE,LDPE, PP,   PE,   PS, PVC,  acrylonitrile butadiene styrene and polycarbonate. .015” to .030” .010” to .015” Acetyl Co-polymer .025” to .062” .015” to .025” .010” to .015” Nylon 66 & Nylon 66 MDS filled .025” to .125” Nylon 6 & Nylon 6 MDS filled .025" to .187" .015" to .025" .005" to .015" Polypropylene & FR Polypro .035" to .250" .015" to .035" Low Density Polyethylene .040" to .250" .015" to .040" .010" to .015" High Density Polyethylene Thicknesses Material Extruded Materials

4. Extruded materials Standard Thickness Tolerances of Extruded Thermoplastic Sheets +/- .007” .187” .126” +/- .005” .125” .094” +/- .003” .093” .047” +/- .002” .046” .005” Tolerance To From

5. Stages of extrusion Feeding from hopper Melting Exit from die Cooling Cut off

6. Process Sheet thickness The layer thicknesses are controlled by the relative speeds and sizes of the individual extruders delivering the materials. Cooling Cooling is achieved by pulling material through a set of cooling rolls, usually 3 or 4 in number. Running material too fast creates an undesirable condition called "nerve" which is basically inadequate contact time given to dissipate the heat present in the extruded plastic. In sheet extrusion, these rolls not only deliver the necessary cooling but also determine sheet thickness and surface texture. Calandering  the molten strand is forced between two  calender  rollers, thus producing films , flakes or sheets  .

7. Overview ……

8. Thank you