Formpressing

Formpressing is a fabrication method in which a powdered material, often ceramic, metal, or a composite powder with a binder, is placed in a die and compacted under high pressure to form a solid green compact. The part is typically densified later through debinding and sintering for ceramics or metal powders, or used as a finished part if sufficient density is achieved.

The process begins with a uniform powder blend. The material is loaded into a die and compressed uniaxially by a top punch against a bottom punch in a hydraulic press. Pressure is maintained for a dwell period to promote particle rearrangement and bonding, after which the green compact is ejected. Variants include cold isostatic pressing (CIP), which applies hydrostatic pressure around the part to improve density uniformity, and hot pressing, which combines forming and densification at elevated temperature. If organic binders are used, debinding is required before sintering. The final step, sintering, densifies the part by diffusion and grain growth under controlled atmosphere or vacuum.

Materials and applications vary widely. Formpressed ceramics are used for electrical insulators, tubes, filters, and precision components; metal powder parts such as bearings, gears, and cutting tools; and certain composite materials in engineering. The method offers good dimensional control, fine surface finish, and relatively high production speed for small to medium-sized parts with simple geometries.

Advantages include straightforward tooling for repetitive parts, high green strength, and good repeatability. Limitations involve restriction to geometries amenable to a mold, tooling costs for dies and presses, and the need for post-forming debinding or sintering, which can introduce defects if density and uniformity are not well controlled.