Hollow compacts pressed from hard metal powders - where die core is removed by dissolving or melting after pressing

摘要

The inner wall or core of the die is made of a solid material removed via heat or a liq. solvent after pressing the compact. The core pref. contains a hole or holes via which the molten core and/or the solvent can be removed. Core is pref. provided with a coating protecting the bore of the powder compact from the heated or dissolved core and/or the solvent. Used e.g. in pressing hollow cylinders from hard metal powders, where the arrangement prevents cracks in the bore of the compact.