Polyamide (PA) is a versatile, technical plastic — almost everyone knows it under the brand name nylon. Detailed information on the properties and production of polyamide can be found here on the ENNEATECH website. Due to its high strength, toughness and abrasion resistance, PA is used to produce sophisticated components that we encounter everywhere in everyday life. There is a wide range of applications for polyamide because, in addition to its good mechanical properties, the plastic also scores points for its high resistance to heat, weathering and chemicals. This makes PA an ideal candidate for a wide range of components in a colorful bouquet of industries.
Processing methods under the magnifying glass
But how are polyamide components actually made? As PA is thermoplastically malleable — i.e. it becomes liquid when heated — it can be “shaped” in different ways. The choice of process depends on the type of polyamide, the component geometry and the desired application. The most common processing methods are injection molding, extrusion and blow molding.
Injection molding
Extrusion
After injection molding, extrusion is the most important processing method for polyamides. The heart of the system is the extruder, which melts the material and then presses the melt through a shaping tool in sufficient quantities at the required temperature and pressure. Depending on the shape of the tool, pipes, profiles, fibers, films and sheets are produced.
The polyamide sheets or rods produced during extrusion can be shaped using CNC machining centers or lathes. These remove material from the compact plastic blanks and thus form, for example, gear wheels, plain bearings, guide bushes, load carrier strips, sealing and sliding rings. These components are often installed in machines and systems, invisible from the outside. Nevertheless, they ensure the reliable operation of machines and devices. Find out more here.
Extruded sheets and films can also be processed using thermoforming. In this process, a heating unit heats the sheet or film to just before the melting point. A tool with the desired shape then moves into the soft material, which is pulled over the mold by compressed air and/or vacuum. In this way, sheets are used to produce cladding parts for caravans, construction vehicles or machines, but thermoformed components can also be found in buses, trains or airplanes in the back shells of seats or side panels. Packaging, load carriers or trays are made from film.
Blow molding
There are different types of blow molding: extrusion blow m olding and injection blow molding. In continuous extrusion blow molding, plastic granulate is melted in an extruder and formed into a tubular preform through a ring-shaped nozzle. This tube emerges continuously from the nozzle. As soon as the preform has reached the desired length, it is transferred to an open blow mold. The mold closes around the tube. Compressed air is blown in through a blow pin, which presses the plastic against the inner walls of the mold. After cooling, the mold opens and the finished hollow body is removed.
In addition to continuous blow molding, the process can also be mapped with an injection-molded preform. The process is divided into several steps: First, the preform is produced in the injection molding process. This resembles a test tube with an already formed bottle neck. The injection-molded preform is heated and then inserted into the blow mold and inflated. The blow molding process is used to produce hollow technical parts from polyamide that have to withstand high mechanical and thermal loads. These include air ducts, fuel tanks or coolant pipes in vehicles. Find out more here.
