Abstract: A process for producing from iron materials a sintered molded part which is pore-free in individual zones or boundary zones but porous in the other zones. The process is based on a molded part brought to a residual porosity of about 10% by volume by conventional powder pressing and sintering processes. By additional process steps such as zonal introduction of additional materials or local mechanical recompacting, certain zones or local areas are brought to a residual porosity of 5% by volume or less; at the same time, a closed pore structure is produced in these zones. Under these preconditions, in a final HIP or sintering HIP process step the sintered molded part can be brought to 100% material density in the pretreated zones so that they substantially completely free from pores. The major advantages include local improvement in material properties and calibratability of the finished sintered molded part.

Abstract: It is the object of the invention to reduce the propagation of noises, in particular shifting noises, in mechanical transmissions. The invention consists in the use of a sintered shaped part formed in an individualized configuration as a noise-damped component, and in particular a gearwheel for a transmission. In the novel configuration, an axially symmetrical sintered shaped part has individual, approximately annular zones of material, for example, an inner rim zone close to the axis and an outer rim zone remote from the axis, the inner and outer rim zones having a high strength and being largely free from voids and a central region being highly porous and comparatively ductile.

Abstract: A gas-permeable form tool for manufacturing casting and core moulds from hardenable moulding sand includes a heteroporous, open-pore material. The wall of the tool contains a first fine-pore layer region adjacent to the moulding sand with a thickness of about 0.2-2 mm and a material density of about 75% to 95% of theoretical specific density and a pore diameter of about 50 .mu.m. The first fine-pore layer comes in contact with a second, large-pore supporting skeleton having a theoretical material density of less than 80% of theoretical specific density and a median pore diameter of more than 100 .mu.m.

Abstract: A process is provided for the manufacture of a gearshifting or sliding sleeve for the forced synchronization of manually shifted automotive transmissions in which the sleeve is manufactured in the form of two substantially symmetrical partial units and is then processed further into a complete sleeve by means of customary joining methods. This process permits sleeves to be manufactured by means of comparatively low-cost powder metallurgical methods through pressing and sintering, and thus makes it possible to dispense with very cost-intensive machining methods.

Abstract: The invention relates to a process for the manufacture of a tubular camshaft in accordance with which process individual cams are subsequently attached to a prefabricated tubular shaft. Such processes acquire ever increasing importance in view of the multivalve technology utilized in automobile construction vis-a-vis processes still predominantly in use today employing casting and subsequent lathing and grinding of camshafts. In accordance with the invention, powdery cam material is directly compressed onto the prefabricated tubular shaft and sintered. With this process, utilization of a single-use compression jacket mold is critical, which jacket mold is preferably manufactured according to the synthetic blow mold process. In addition to its economical nature, this process provides the advantages of enabling greater design flexibility with respect to molding and selection of materials to be used.

Abstract: An automotive transmission lubricated friction clutch is provided having a synchronization ring and matching cone; these parts form a friction pairing. Materials having different friction characteristics and friction wear resistances are used for the friction surfaces forming the friction pairing. A specific friction material is provided having desirable friction characteristics but lacking pores or drainage thread for one friction surface, and a microporous sintered material having a friction-effective area A of 50% <A <90% of the total friction surface and pores with a mean diameter of <300 .mu.m for the other friction surface. Either the synchronization ring or the matching cone are designed to represent one or the other form of friction surface, as desired. Lubricated friction clutches for automotive transmissions can be manufactured according to the invention that have increased life expectancy, shorter shifting times, smaller sizes and reduced manufacturing costs as compared to other clutches.