A numerical analysis program of compression molding for cups has been developed and the method which reduces the forming load was simulated. It was found that the initial shape of the melted object affected the forming load and the forming load for a wide circular sheet having thickness distribution was lower than that for a cylindrical melt lump. We could also confirmed that the blank holder had an important effect to prevent from the dragging of a melted object into the core during the compression process. The seal part of cup was filled with melted resin in a comparatively earlier stage of compression compared with the case of using a melt lump. We could show that a wide circular sheet having a thickness distribution needs a lower formina load.
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