For manufacturing plastic pipes, there is a use of a process called profile extrusion. This process is used to generally produce plastic products with continuous cross-sections. Typical examples include decorative molding, drinking straws, plastic evestroughing, window trimming and numerous variety of other products polymers that are melt into the hollow mold cavity under application of high pressure. A typical profile extrusion process works like this. The plastic is first fed in a pellet form into the Extruder. The material gets conveyed forward continuously by a rotating screw inside a heated barrel. Here it is being softened by heat and friction. The softened plastic is subsequently forced out via a die, directly into the cool water. The product gets solidified here. Afterwards it is conveyed onwards into the take-off rollers. It is actually the take-of-rollers which does the pulling act of the softened plastic from the die. The die is basically a metal plate that is placed at one end of the extruder. It has a section cut out of its interior. This cutout, along with the speed of the take-off rollers, plays a determining factor in the cross-section of the product being manufactured.

Many grades of thermoplastic can be extruded based on the application. The two primary categories are rigid and flexible extrusions. Flexible materials are needed for profiles that are required to serve as seals (for example say refrigerator gaskets) while rigid thermoplastics are needed if structural integrity is required. Typical examples include rigid polyvinyl chloride, guttering and siding. The next section takes a look at the materials available.


Features of Profile Extrusion

• Low Part Cost
• Low Tool Cost
• High Production Capability
• Shorter lead times in production
• Uniform cross section of parts
• Multiple materials/durometers are possible in the same part

Materials for Profile Extrusion
Generally two classes of materials are manufactured into profiles. This of course depends upon the application and needs of the final product. These two classes, rigid and flexible profiles, are differentiated based on the starting material and final properties of the profile.

Rigid profiles are typically hard and relatively inflexible, often found in building applications. They can be manufactured using different resins. Flexible profiles on the other hand are flexible. The parts get bent easily, and are often soft (Typical durometer hardness range for them is from 50–95 ascertained by Shore A test). They are also easily compressible and generally used as internal components of items. The following table summarizes a variety of resins that are used in the profile extrusion.

Resins for flexible applications	Resins for rigid applications
Plasticized PVC	ABS
TPO (thermoplastic olefins)	Polycarbonate
Thermoplastic rubbers	Non-Plasticized PVC
Thermoplastic Urethanes	Polypropylene
LDPE	HDPE

Typical examples of Profile Extrusion
The following examples illustrate clearly illustrate the broad possibilities of Profile extrusion.

• Window profiles
• Sealing sections
• Modular drawer profiles
• Decorative trims