Tableting Presses Information
Tableting presses are used for uniaxial pressing powdered materials into shaped tablets or compacts. Tableting presses usually operate at high speeds. Parts can often be pressed and sintered to dimensional tolerance levels that do not require additional machining. For demanding applications, cold pressed and sintered parts may require subsequent coining/repressing, infiltration, hot pressing or forging to reach the required density and strength.
Tableting presses are designed in two configurations: multi-station tableting press and single station presses. Multi-station tableting presses, also referred to as rotary presses, use a punch and die system with multiple stations or punches for compacting materials into tablets, or metal powders into simple flat or multilevel shaped parts like gears, cams, or fittings. Rotary types have a series of stations or tool sets (dies and punches) arranged in a ring in a rotary turret. As the turret rotates, a series of cams and press rolls control filling, pressing and ejection. Pharmaceutical tablet and high volume metal part production facilities often use high-speed automatic rotary presses.
Single station presses consist of a single tool set (die and punch set) in a die table. Single action opposed ram presses use a die with both upper and lower punches. Anvil type presses have only a die and single lower punch. Single station compacting presses are available in several types basic types such as cam, toggle / knuckle and eccentric / crank presses with varying capabilities such as single action, double action, floating die, movable platen, opposed ram, screw, impact, hot pressing, coining or sizing.
Uniaxial hot presses are used to consolidate ceramic carbide and other refractory powders, as well as diffusion bond materials. Larger powdered metal parts are typically compacted on single station, uniaxial presses.
When working with tableting presses, force is the appropriate measure to determine the degree to which materials may be compacted. By contrast, pressure is the determining factor when working with isostatic presses. The maximum operating press load or force required to reach the desired density during part production when using a tableting press is expressed as follows:
Press Load = Required compaction pressure (psi) for the material x Part's Projected Area (sq. in.)
Additionally, the functionality of a given tableting press is determined by three important specifications; its unit rate production, the diameter or width of the die cavity, and maximum internal length of the cavity. Unit rate production is the number of units produced per minute or hour. The unit's capacity maybe stated in terms of compacts, parts, tablets, pills, strokes or cycles per unit time. Diameter and length of the inner cavity are determinants of the maximum size of the die that the press may accommodate. This in turn reflects the size or type of compact that the press can produce.
Tableting presses are used in a wide range of industrial activities including the compaction of confections, cosmetics, detergents, electronic components, ferrite cores, healthcare products and pharmaceuticals, food service, nuclear fuel pellets, and precision metal parts.