Sintered Porous Powder Metals are usually produced either by gravity sintering, which relies primarily on high temperature or by pre-compression of the powder at room temperature into a compacted green state followed by sintering. Both methods are used in porous metal production. Gravity sintering is ideal for flat sheet, and yields materials suitable for use as filter media with maximum permeability and dirt holding capacity. The conventional method of pressing and sintering is useful to produce shapes such as porous bushings or seamless cylinders.