Extrusion is a process that forces plastic or molten material through a shaped die under pressure to form various products like thin films, tubing, pipes, and profiles. Common materials that are extruded include nylon, polyethylene, polypropylene, and polyvinyl chloride. The extrusion process involves feeding material into a hopper, melting it, forcing it through a die, cooling it with rollers, and cutting it to final lengths or widths. Sheet thickness is controlled by the speeds and sizes of the extruders delivering the materials, while cooling is achieved through rollers over a set number of passes to adequately dissipate heat without creating defects. Calendering may also be used to force the mol

2. Muhammad Ahmad
14-MME-S1-309
Metallurgical & materials engineering

3.  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.

4.  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
ThicknessesMaterial
Extruded Materials

5. Standard Thickness Tolerances of Extruded
Thermoplastic Sheets
+/- .007”.187”.126”
+/- .005”.125”.094”
+/- .003”.093”.047”
+/- .002”.046”.005”
ToleranceToFrom

6. 1. Feeding from hopper
2. Melting
3. Exit from die
4. Cooling
5. Cut off

7.  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 .

9. Thank you