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Rheology in Polymer and Rubber Processing
Published in B. R. Gupta, Rheology Applied in Polymer Processing, 2023
In compression moulding the components are formed by introducing in the mould, a preheated and preformed shape approximately having the shape of the cavity and compressing and heating it. The melt flows under pressure to fill the mould cavity and then the cross-linking or setting takes place to produce the component shape. The polymer used may be a thermoplastic, partially polymerized thermosetting polymer, a rubber compound containing curatives or a thermoplastic elastomer. After the preformed shape is placed in the mould and the moulds are closed, the material receives heat from the platens and the melt flows in to the cavity to fill it completely before the curing reaction starts.
Plastics
Published in Sherif D. El Wakil, Processes and Design for Manufacturing, 2019
Compression molding is used mainly for processing thermosetting polymers. The process involves enclosing a premeasured charge of polymer within a closed mold and then subjecting that charge to combined heat and pressure until it takes the shape of the mold cavity and cures. Figure 8.9 shows a part being produced by this process.
Enhancement of Impact Strength in Jute Fiber-Reinforced Polypropylene-Spent Coffee Ground Composites
Published in Jose James, Sabu Thomas, Nandakumar Kalarikkal, Yang Weimin, Kaushik Pal, Processing and Characterization of Multicomponent Polymer Systems, 2019
Specifically designed to facilitate the replacement of metal components with polymers (and other composites), the compression molding process is a method of molding in which a preheated polymer is placed into an open, heated mold cavity. The mold is closed with a top plug and pressure is applied to force the material to contact all areas of the mold. Throughout the process heat and pressure are maintained until the polymer has cured.
Processing of PLA/pineapple fiber based next generation composites
Published in Materials and Manufacturing Processes, 2021
Ujendra Kumar Komal, Manish Kumar Lila, Inderdeep Singh
Therefore, several factors have to be considered before selecting a specific processing route. A few of these are; part geometry, size, properties of the constituents, and the number of products.[27] As mentioned, the geometry of the component is crucial in selecting a suitable processing route. The composite products with constant cross-section profiles are generally manufactured using pultrusion and extrusion processes. However, pultrusion is generally employed to fabricate polymeric composites with reinforcement in the form of a continuous strand. However, the extrusion process is preferred for fabricating the short fiber-based composites.[28,29] Compression molding is generally used to fabricate composite products having flat surfaces in which the reinforcement is usually in the woven (unidirectional and bidirectional) form, whereas injection molding is recommended for manufacturing composites incorporating short fibers. With natural fibers, there is also a constraint on the fiber length.
Advanced robotics and additive manufacturing of composites: towards a new era in Industry 4.0
Published in Materials and Manufacturing Processes, 2022
Hetal Parmar, Tayyab Khan, Fausto Tucci, Rehan Umer, Pierpaolo Carlone
In compression molding processes, the reinforced polymer is precisely shaped by compression between two halves of a mold under high pressure,[26–29] material temperature during forming and curing is monitored, and controlled. It is commonly used to shape composite parts from thermoplastic prepregs.[30] As an alternative, a laminate of chopped fabrics and resin paste can be used.[31] In liquid composite molding processes, the liquid resin flow is driven by means of pressure gradients applied within a mold, where the fibrous reinforcement has been previously disposed.[32–34] Depending on the specific variant of this process, other variables can be controlled, such as resin polymerization, material thickness, and void content.[35–37] Pultrusion and filament-winding processes are commonly referred to as continuous processes for FRPs.[38] The pultrusion process is the most effective choice to produce constant cross-section profiles,[39] for instance as structural elements in buildings, bridges, and civil structures.[40] In this process, the orientation of the fiber, the shape of the profile, and the resin polymerization reaction are precisely controlled.[39,41,42] Filament winding is based on the automated deposition of wet fibrous bundles or prepreg tapes on a rotating tool called a mandrel.[2] The rotation of the mandrel and the movement of the depositing head determine exactly the fiber orientation.[43,44] The most challenging aspect in filament winding is the reproduction of concave shapes which, in most cases, cannot be generated by adopting the typical geodesic paths for tape deposition.[45–47]
Mechanical properties of carbon fiber paper reinforced thermoplastics using mixed discontinuous recycled carbon fibers
Published in Advanced Composite Materials, 2018
Haowen Wei, Wataru Nagatsuka, Hooseok Lee, Isamu Ohsawa, Ken Sumimoto, Yi Wan, Jun Takahashi
Compression molding was chosen as the forming method in this study since it is characterized by cost efficiency and the possibility to realize parts with complex geometries. However, the discontinuous rCF and PA6 fibers were expected to cause many voids during melting. Therefore, sufficient compression molding pressure for CPT was determined first. The mold used in this study was 110 mm in width and 110 mm in length. To produce a 2-mm-thick CPT plate, 20 layers of CP were necessary. These were dried at 90 °C for over 6 h by a drier with a vacuum pump before molding.