Contact pressure molding

Contact molding Also called open molding or contact pressure molding. It is a process for molding RPs in which the reinforcement and plastic are placed in a mold cavity. Cure is either at room temperature using a catalyst-promoter system or by heating... 

TSs has experienced an extremely low total growth rate, whereas TPs have expanded at an unbelievably high rate. Regardless of the present situation, CM and TM are still important, particularly in the production of certain low-cost products as well as heat-resistant and dimensionally precise products. CM and TM are classified as high-pressure processes, requiring 13.8-69 MPa (2,000 to 10,000 psi) molding pressures. Some TSs, however, require only lower pressures of down to 345 kPa (50 psi) or even just contact (zero pressure). 

Like the snap back process, billow forming is a sheet pre-stretch process used with a male mold. The sheet is clamped across a pressure chamber and is billow pre-stretched by applying a low magnitude positive air pressure to the chamber. The male mold is then moved into the stretched sheet until the clamp seals on the mold periphery. Contact between the mold and controlling the rate at which the pressure chamber is vented to compensate for the advancing mold can regulate the sheet. 

Low-cost molds for contact and low-pressure molding can be made from reinforced TS polyester or epoxy compounds with glass fiber and/ or mineral filler reinforcement. These constructions have also been used to make prototype molds for compression and injection molding, with the advantages that they can be produced quickly and at low cost (often in-house) and can readily be modified. Latest technology uses blocks of resin-based compounds that can be machined by computerized instructions, for production of protot5 e molds. 

Land area The area of those surfaces of a mold that contact each other when the mold is closed, measured in a plane perpendicular to the direction of application of the closing pressure. 

Topaq This mold pressure analysis system is used in conjunction with the companies Pressurex stres- indicating films. It provides a perspective of the distribution and actual magnitude (psi) of pressure between any contacting or impacting surfaces. Films change colors in proportion to the amount of pressure applied. A... 

Blow molding is now a highly developed process with many variant forms (Fig. 10.31). At its most basic, the process involves melt processing a thermoplastic into a tube that is generally referred to as a parison. While still in a heated ductile plastie state, the parison is clamped between the halves of a eooled mold, so that the open top and bottom ends of the parison are trapped, compressed, and sealed by the mold faces. A blowing tube is also trapped in one of the parison ends, creating a chaimel through which air pressure is introduced within the sealed parison. Air pressure eauses the parison to expand like a balloon, so that it takes the form of the mold cavities. Contact with the eooled mold chills the thermoplastic to its solid state, so the form is retained after the mold is opened and the part removed. 

After reaching a mold temperature of 120 °C, we slowly bring the molds in contact with each other with a linear speed of 0.5 mm/min and apply pressure to the heated PMMA. Even though the different sized cones come in contact with the top surface of the PMMA at different moments in time as the molds are brought in contact with the PMMA, the PMMA remains more or less flat on the bottom mold. 

The mold is usually prepared with orifices to permit air trapped between the sheet and the mold to escape and ensure uniform, close contact of the plastic with the mold surface. By clamping the sheet beyond the perimeter of the piece, plastic may be drawn from the peripheral areas into the mold, ensuring uniformity. Both pressure and vacuum are employed to force the softened plastic sheet into the mold. 

Packaging. The beer in pressure tanks is transferred to bottling, canning, and racking, or in some cases, to road tankers. During this filling operation it is important that the beer does not come into contact with oxygen, does not lose carbon dioxide, and is not contaminated by molds, yeasts, or bacteria. 

Contact molding Process whereby layers of resin-impregnated fabrics are built up one layer at a time onto the mold surface forming the product. Little or no pressure is required for laminate curing. 

Molding, contact pressure Method of molding or laminating whereby... 

This low pressure process, also known as elastic reservoir molding, consists of making basically a sandwich of plastic-impregnated open-celled flexible polyurethane foam between the face layers of fibrous reinforcements. When this plastic composite is placed in a mold and squeezed, the foam is compressed, forcing the plastic outward and into the reinforcement. The elastic foam exerts sufficient pressure to force the plastic-impregnated reinforcement into contact with the heated mold surface. Other plastics are used. 

Contact Molding. Spray-up Pressure Bag Filament Winding Continuous Pultrusion Premix/ Molding Compound Matched Die Molding with Preform or Mat... 

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