Low Pressure Molding

S.V. Atre, The Pennsylvania State University

There are several shape-forming techniques that utilize powder-binder suspensions (Ref 17). In recent years, a number of methods have emerged in which molding occurs under low shear rate conditions. These methods are collectively referred to as low-pressure molding (LPM). Figure 8 shows the generic steps involved in LPM. A well-mixed feedstock consisting of the powder and binder constituents is introduced into a mold at pressures below 0.7 MPa (100 psi). Generally, the viscosity of the feedstock is such that the material can flow at room temperature (1 to 103 Pa • s). The feedstock is solidified in the mold to the desired shape. The green part is removed from the mold and is subjected to thermal debinding and sintering cycles to high final densities (90 to 100% of the theoretical value). The main variations in the process occur in the binder composition and in the solidification stage.

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