Flexible bag moldings

An air inflated-pressurized flexible-type envelope can replace the plunger. This process provides higher glass content and decreases chance of voids. Limitations include extensive trimming and only one good surface. 

This refers to many different fabricated RP processes such as contact/ low to high-pressure laminates, and continuous laminations. It usually identifies flat or curved panels using high pressure rather than contact or low pressure. It is a product made by bonding together two or more layers of laminate materials. The usual resins are TS such as epoxies, phenolics, melamines, and TS polyesters. A modification of this process uses TPs. The type of materials can be endless depending on market requirements. Included are one or more combinations of different woven and/or nonwoven fabrics, aluminum, steel, paper, plastic film, paper, etc. 

In industry, for almost a century these laminates are used for their electrical properties, impact strength, wearing qualities, chemical resistance, decorative panels, or other characteristics depending on laminate construction used with or without a surfacing material. They are used for printed circuit boards, electrical insulation, decorative 

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Compression Molding Flexible Plunger Flexible Bag Molding Laminate Hand Lay-Up Vacuum Bag Molding Vacuum Bag Molding and Pressure Pressure Bag Molding Autoclave Molding Autoclave Press Clave Wet Lay-Up... 

Veneers laid up on a flat table. Complete assembly is positioned in a mold at one time used primarily on curved surfaces to be molded by the flexible bag process. 

Wet- and dry-bag are two techniques for isostatic molding which are principally identical but operationally different. The wet-bag process is similar to the basic molding procedure in which the mold is submerged in the pressurization fluid. In the dry-bag technique, the mold and the bag are fixed in place and the functions of the mold and the pressurization vessel are combined. The pressurization fluid is introduced through a high-pressure liquid supply system behind the flexible bag (Fig. 5.17). The mold assembly is designed to withstand this pressure. The term dry-bag contrasts the absence of submerged mold and wet mold assembly. 

Figure 5.17 Mold for the production of a beaker using an outer flexible bag and inner rigid part.

Bag Molding Bag molding is essentially an extension of the lay-up process. The lay-up structure is covered by a flexible airtight bag and either an external pressure is applied or vacuum is created inside the bag-mold enclosure. This improves the properties of the resultant composite by driving out volatile substances and increasing the volume fraction of reinforcement. 

In vacuum-bag molding the reinforcement and the resin mixed with catalyst are placed in a mold, as in the hand layup method, and an airtight flexible bag (frequently rubber) is place over it. As air is exhausted from the bag, atmospheric air forces the bag against the mold (Figure 2.46). The resin and reinforcement mix now takes the contours of the mold. If the bag is placed in an autoclave or pressure chamber, higher pressure can be obtained on the surface. After the resin hardens, the vacuum is destroyed, the bag opened and removed, and the molded part obtained. The technique has been used to make automobile body, aircraft component, and prototype molds. 

To ensure release of bleeder material from a bag-molded cured part and to form a flexible diaphragm (bag) over the lay-up during the cure of the TS plastic, a parting... 

Vacuum bag molding is a modification of hand lay-up, in which the layup is completed and placed inside a bag made of flexible film, and all edges are sealed. The bag is then evacuated, so that the pressure eliminates voids in the laminate, forcing excess air and resin from the mold. By increasing external pressure, a higher glass concentration can be obtained, as well as better adhesion between the layers/plies of laminate. Some items for the process can be disposable. 

Design factor Bag molding Flexible plunger molding Vacuum injection molding Matched die molding Comp, molding... 

Isostatic pressing is a compaction technique through the application of a uniform hydrostatic pressure to the powder confined in a flexible rubber container. There are two modes of isostatic pressing (i) wet-bag pressing and (ii) dry-bag pressing. In wet-bag isostatic pressing, the powder is filled in a flexible rubber mold, which is then submerged into a pressure vessel filled with oil as fluid, as shown... 

Bag molding (blanket molding)—A method of molding or bonding involving the application of fluid pressure, usually by means of air, steam, water, or vacuum, to a flexible cover which, sometimes in conjunction with the rigid die, completely encloses the material to be bonded. 

RIFT or vacuum resin infusion is a hybrid of RTM and vacuum bag molding. In RIFT, one mold face of RTM is replaced by a flexible polymeric bag and resin is introduced into the mold by vacuum only. The process is better known in the USA as SCRIMP, which is a patented process. During resin infusion, the initial dry fiber compaction affects the permeability to resin flow and is time dependent, but when the resin enters the fibers, it appears to act as a lubricant and leads to further compaction. 

Bag molding Consolidation of prepreg in a mold by application of fluid pressure through a flexible membrane. 

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