Processo de moldagem por compressão – Vantagens e desvantagens

Compression molding process – Advantages and disadvantages

June 27, 2024 Roberto Magalhães

Compression molding process – Advantages and Disadvantages

Compression molding is a well-known technique for developing a variety of composite products. It is a closed molding process using high pressure. In this method, as shown in figure 1, two combined metal molds are used to manufacture the composite product. In compression molder, the base plate is stationary while the top plate is movable. The reinforcement and matrix are placed in the metal mold and the entire assembly is held between the compression molder. Heat and pressure are applied as per the requirement of the compound for a defined period of time. The material placed between the molding plates flows due to the application of pressure and heat and acquires the shape of the mold cavity with high dimensional accuracy that depends on the mold design. The curing of the compound can be carried out at room temperature or at some elevated temperature. After curing, the mold is opened and the composite product is removed for further processing.

In principle, a compression molding machine is a type of press that is vertically oriented with two molding halves (top and bottom halves). Generally, hydraulic mechanism is used for applying pressure in compression molding.

Process Parameters for Compression Molding

The control parameters in compression molding method to develop superior and desired properties of the composite are shown in the figure. All three model dimensions (pressure, temperature, and application time) are critical and must be optimized effectively to obtain a custom composite product, as each model dimension is equally important to the others. If the applied pressure is not sufficient, it will lead to poor interfacial adhesion of the fiber and matrix. If the pressure is too high, it can cause fiber breakage, expelling enough resin from the composite system. If the temperature is too high, the properties of the fibers and matrix can be changed. If the temperature is lower than desired, the fibers may not be adequately wetted due to the high viscosity of polymers, especially for thermoplastics. If the application time of these factors (pressure and temperature) is not sufficient (high or low), it may cause any of the defects associated with insufficient pressure or temperature. The other manufacturing factors such as mold wall heating, closing rate of two mating plates and demolding time also affect the production process.

Application:

1. The method is equally applicable to both thermosetting polymers and thermoplastic polymers.

composites.

2. A wide spectrum of applications ranging from kitchen products to automobiles, toys, electrical items and aircraft parts.

3. Typical products include automobile dashboards, roofs, lifeguard gates, battery trays, fenders, hoods, bumpers, spoilers, air deflectors, furniture, kitchen bowls and trays, tableware, buttons, containers large, recreational vehicle body panels, medical equipment (ultrasound equipment).