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Blow extrusion of plastic film. The manufacture of plastic film for products such as food packages, shopping bags, and continuous sheeting is achieved using a blown film line. [5] This process is the same as a regular extrusion process up until the die. There are three main types of dies used in this process: annular (or crosshead), spider, and ...
During an extrusion process it is essential to consider the surface finish of exposed product surfaces. As a general rule, the narrower an exposed surface, the more uniform its finish becomes. Webs, flanges and abrupt changes in metal thickness may show up as marks on the opposite surface of an extrusion, particularly on thin sections. The ...
A plastic extrusion machine extrudes plastic in a continuous profile. The main machine is usually called the host, and its accompanying equipment are called the plastic auxiliary equipment. Plastic extruders can make plastic film/wrapping, packing tape, corrugated sheets, plastic lumber, pipes, tubes, insulated wire, monofilament and nets.
Die swell is an expansion of the melt as the pressure is released, and is dependent on polymer chemistry and die design. After curing, the solid, continuous part is drawn onto a take-up roller or cut into transportable lengths, depending on the type of part. This process may vary significantly depending on the type of die and extrusion process. [1]
Plastic films are usually thermoplastics and are formed by melting for forming the film. [2] Cast – Plastics extrusion can cast film which is cooled or quenched then wound up on a roll. Extruded film can be stretched, thinned, or oriented in one or two directions. Blown or tubular process forces air into an extruded ring to expand the film ...
The direct spinning process avoids the stage of solid polymer pellets. The polymer melt is produced from the raw materials, and then from the polymer finisher directly pumped to the spinning mill. Direct spinning is mainly applied during production of polyester fibers and filaments and is dedicated to high production capacity (>100 ton/day).
Mixing elements or convey elements are used in various formations. Extrusion is common in the application of adding colorant to molten plastic thus creating specific custom color. Extrusion is also a process used in fused filament deposition 3D printers, whereby the extruder is often composed of a geared motor pushing plastic filament through a ...
Co-kneaders and twin screws (co- and counter rotating) as well internal mixers are the most common used compounders in the plastic industry. [3] The extrudate, which look like long plastic strands, are then cooled in a water bath, or by spraying as the conveyor belt moves it to the granulator. The granulator breaks the strands into the desired ...