An Overview of Plastic Processing – types of Processing & Machines

In this article, we will know various types of processing machines used to make the wide range of plastic products in use throughout our lives. So you can understand how plastics processing works with the help of various machines & technology.

Injection Molding Process –

First of all, let’s talk about the Injection molding process because it is widely used in plastic products production. This process is used to make plastic parts using two-part molds that, when closed, are injected with melted plastic to form individual parts.

In injection moulding process, the Material gravity flows into the injection machine screw where it is melted by the compressing motion of the screw and then inject it into the mold to form the part or parts. After that mold is quickly cooled by cooling pumps, letting the parts solidify. The mold opens to release the parts and the mold closes again to repeat the cycle, over and over again.

Molding cycles can last anywhere from one second for tiny parts made in tiny molding machines, to minutes for large parts made in presses the size of a building.

Extrusion Moulding Process –

In Plastic Processing, Extrusion processes use the same plastic melting operation as injection molding, but there is no mold, and the resin compressing screw rotates constantly, and product is created continuously.

Extrusion uses a die, a hollow form that molten plastic is pushed through, to create its specific shape and thickness. A water bath or spray chamber then cool the extruded shape and often provide pressure and or vacuum controls to properly size the product as it passes through. Belts or cleated pullers apply smooth tension on the product and keep it moving in pace with the extruder. Here cutter or saw create the final product length, or a winder creates spools of the final product.

Blow Moulding Process –

A mixture of extrusion and injection molding is found in the blow molding process, where plastic is continuously extruded into a tube shape and then clamped at a mold and blown into its shape with compressed air.

It’s a process that often operates in a shuttle movement with a set of molds. Each mold takes a turn grabbing a section of extruded tube called a paracin and shuttling it to one side to blow it into a bottle shape, letting it cool, and then releasing it to be filled with product or shipped. Each mold alternates with a second mold doing the same thing for maximum productivity.

Co-Extrusion Moulding Process –

Extruding two or more materials through a single die so that materials merge or weld together into a single structure before cooling called co-extrusion. multiple extruders for what is called co-extrusion. Co-extrusion is used to create bottles made up of multiple layers, and each layer possesses special characteristics like suitability for food contact, an outside color for brand awareness, ultraviolet light protection for long shelf life of the product, a layer of regrind for economical reuse of scrap, and many times, barrier and adhesive layers are included to separate and bond layers for a tough cohesive bottle.

A high volume form of blow molding uses many molds mounted onto a continuously-rotating wheel mechanism. The extruder creates a hollow tube, and as the wheel rotates, each of its molds will open, grab a paracin from the extruder die, blow the paracin into a bottle, allow it to cool, and then place it onto a conveyor, producing a continuous stream of finished bottles originating from that continuous flow of plastic from the extruder. These wheel machines can also produce co-extruded bottles containing layers designed to meet the needs of the product and to use reclaimed material for maximum economy and recycling benefits.

The very popular sails of plastic bottles for carbonated beverages has created a unique process for blow molded bottles made specifically from polyethylene terephthalate or PET. For PET blow molding, bottles are first created in a test tube shape, injection molded pre-form, and then, in a separate operation, reheated and blown into their final shape. This two-stage process creates bottles that we, as consumers, know to be thin-walled yet capable of containing gaseous carbonated beverages without losing pressure or exploding, even if they are dropped.

Blown Film Extrusion Process –

In the blown film extrusion process, thin plastic material for products like garbage bags or the sheeting used in construction industry and packaging are produced. A very thin die opening, which is often fed by multiple extruders, faces upward in a round shape. A tall, thin continuous bubble is produced vertically by this process, and it’s cooled as it flows upward, typically feet or more, where it is then folded and brought back down and placed onto rolls, or converted into popular film products. And all these processes from injection molding to film extrusion rely on Conair products to support their productivity and efficiency.

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