Plastic forming and processing refers to the manufacturing of plastic products. In plastic processing, products are produced through the processing and fabrication of plastic semi-finished products, molded parts, films, or plastic fibers. Plastic raw materials are usually supplied in the form of granules, powders, sheets, or films.
During the processing, plastics in granular or powdered form are typically heated and subjected to casting, spraying, calendering, extrusion, pressing, blow molding, or foaming. Therefore, the forming process is particularly crucial in plastic processing. Furthermore, if additives are incorporated into plastics to achieve or enhance specific properties, it is referred to as compounding.
Various plastic processing methods
As mentioned above, the forming process is crucial in plastic manufacturing. There are various methods that need to be distinguished. Some of the more important methods are described below:
Extrusion
During the extrusion process, plastic is fed into the barrel where the screw operates through a hopper, and this constitutes an extruder. The pitch of various sections of the screw varies. They are respectively used for melting, homogenizing, venting, and compression. Extruders can be used in multiple aspects. They can be used for producing granules, recycling plastics, and manufacturing profiles, sheets, textile fibers, and films. In film production, the extruder is equipped with a slot die and/or used in conjunction with a calender. If it is a multilayer film, several extruders are often required to simultaneously produce film products.
Rolling
Calendering is a plastic forming process that requires a series of rollers to complete or flatten plastic sheets. It is primarily used in the production of films, thin plates, and flooring materials.
Rotational molding
Rotational molding is a special production process used to manufacture large, hollow, seamless plastic parts. During the production process, melted plastic particles are deposited on the inner surface of the rotational molding mold as they cool. Due to the characteristics of the rotational molding mold, different wall thicknesses can be achieved even within a single mold.
Foaming
Foaming can be divided into three categories. In chemical foaming, the gas that causes the material to foam is released during the polymerization process. In physical foaming, a low-boiling liquid is added to the reaction mixture, which evaporates during the polymerization process, thus forming typical bubbles. Finally, in mechanical foaming, gas is injected into the plastic melt while stirring.
Injection blow molding mold
In blow molding, a thermoplastic preform expands within a mold. Compressed air causes it to adhere to the inside of the mold and holds it in place as it cools. This process is primarily used to produce items such as bottles, buckets, and automobile fuel tanks.
What is injection molding?
However, injection molding stands as the primary and most widely used forming process in plastic processing. It is an excellent manufacturing technique, especially suited for mass production. Typically, any mass-produced parts made of glass, rubber, metal, or plastic are produced through injection molding. The process is straightforward: melted plastic is injected into a mold, allowed to cool, and then the plastic product is ejected. It comprises four stages: mold clamping, injection, cooling, and ejection.
As the cooling stage occupies the most time, it also serves as a lever to enhance production efficiency. This is the secret weapon of injection molding: copper! Due to its unique properties, copper-based alloys such as aluminum bronze or beryllium bronze can shorten cycle times, boosting production efficiency by up to 80%! This can save companies 10-40% of production costs.
Therefore, reducing cycle time is only one of the reasons for cost savings in aluminum bronze. Other reasons include reducing the rate of defects. In addition, the excellent thermal conductivity of copper-based alloys can greatly reduce warping and deformation. This is due to the advantage of improved cooling, as molds made of aluminum bronze distribute heat more evenly than steel molds.
