In the realm of composite product development, compression molding reigns as a renowned and well-established technique. This closed molding process operates under the influence of high pressure, resulting in a diverse array of composite products. The process, illustrated in Figure 1, hinges on the utilization of two precisely matched metal molds to craft composite products.
Here’s a breakdown of the compression molding process:
- Within the compression molder, the base plate remains stationary, while the upper plate is mobile.
- Reinforcement and matrix materials find their place within the metallic mold, and the entire assembly is positioned within the compression molder.
- Heat and pressure are meticulously applied, tailored to the specific requirements of the composite, and for a designated duration.
- As pressure and heat take effect, the materials situated between the molding plates flow, adopting the precise shape of the mold cavity with remarkable dimensional accuracy, contingent upon mold design.
- Composite curing can occur either at room temperature or at an elevated temperature. After this critical step, the mold is opened, and the composite product is liberated for subsequent processing.
In essence, a compression molding machine resembles a vertical press with two molding halves, the top, and bottom halves. Typically, hydraulic mechanisms take charge of pressure application in compression molding.
Achieving optimal composite properties via the compression molding method is reliant on mastering the controlling parameters, encompassing pressure, temperature, and the duration of application, as showcased in the figure. Each dimension within this trio bears equal significance. Inadequate pressure may result in subpar fiber-matrix adhesion, while excessive pressure can lead to fiber breakage and resin expulsion. Temperature fluctuations can alter the properties of fibers and matrices, while inadequate wetting of fibers can occur at low temperatures. Time, an integral factor, plays a role in preventing defects linked to insufficient pressure or temperature.
Various manufacturing factors, such as mold wall heating, the rate at which the matching plates close, and the demolding time, further influence the production process.
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