Vacuum-assisted processing

Key words vacuum assisted resin transfer molding (VARTM), vacuum-assisted process (VAP), modeling, defects, compaction. 

Li W, Krehl J, Gillespie Jr. J W, Heider D, Endrulat M, Hochrein K, Dunham M G, Dubois C J (2004) Process and performance evaluation of the vacuum assisted process, J Compos Mater 38 1803-1814,... 

FIGURE 1.231 Stitching template for stitching integration of load input elements 1.8.4.3 Molds for Vacuum Assisted Processes... 

The venting of the mold can also be important for the process control. In vacuum-assisted processes, the vacuum pump stays active during the entire injection process and is protected from penetrating matrix material by a resin trap. If a plastic tube is used for this venting line, the moment the resin flows out of the mold can be easily recognized. If more lockable exits of a cavity are used, an online flow path control can also be realized in ciosed mold concepts. The construction of a closed injection mold with two fixed moid haives is dependent on which effort for the actual application is justified or necessary for the process-related implementation. 

Resin transfer molding With vacuum assisted RTM, this process can be called infusion molding. RTM usually uses liquid TS plastics that is transferred or injected into an enclosed mold usually at low pressures of about 60 psi (410 kPa) in which reinforcement... 

Why would we use a plug assist process instead of a vacuum forming process ... 

Liquid Composite Molding (LCM) is the common name for several similar processes for the manufacturing of polymeric fiber reinforced composites. Widely used processes that belong to this class are Resin Transfer Molding (RTM), Vacuum-Assisted Resin Injection (VARI), and Structural-Reaction Injection Molding (S-RIM). 

Giberson, R. T. 2001. Vacuum-assisted microwave processing of animal tissues for electron microscopy. In Microwave Techniques and Protocols (R. T. Giberson andR. S. Demaree, eds.), pp. 13-23. Humana Press, Totowa, NJ. 

Subsequent to freeze stabilization, wet books can be thawed and air dried with or without interleaving or they can be vacuum dried in heated chambers (5). The moisture in frozen books can be sublimed by freeze drying (10) or removed by a vacuum/thaw/outgassing process (8), with microwave energy (6, 14), with dielectric energy (6), or by solvent extraction with or without vacuum assistance (5). 

RTM can also incorporate vacuum to assist plastic melt flow. With vacuum-assisted RTM the process is called infusion molding.300 This process could be identified as a take-off to the Marco process.3... 

The vacuum assisted liquid molding process has been used for the manufacture of large composite parts. In this process, a preform is placed in an open mold and a plastic vacuum bag placed on top of the mold. A vacuum is created in the mold using a vacuum pump. A resin source is connected to the mold. As vacuum is drawn through the mold, resin infuses into the preform. Application includes the fabrication of large products with complex geometry such as panels of allcomposite buses, railroad cars, and vehicle components. 

Thermoforming has close similarities with vacuum forming, except that greater use is made of air pressure and plug assisted forming of the softened sheet. The process is invariably automated and faster cycle times are achieved than in the vacuum forming process. Only thermoplastic sheet can be processed by this method. 

In order to find the domain of LCVD, it is necessary to compare various vacuum deposition processes chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma chemical vapor deposition (PCVD), plasma-assisted CVD (PACVD), plasma-enhanced CVD (PECVD), and plasma polymerization (PP). All of these terms refer to methods or processes that yield the deposition of materials in a thin-film form in vacuum. There is no clear definition for these terms that can be used to separate processes that are represented by these terminologies. All involve the starting material in vapor phase and the product in the solid state. 

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