Molding isostatic

Isostatic Molding of Teflon TFE-Fluorocarbon Resins, preliminary information buUetia, E.I. du Pont de Nemours Co., Wilmington, Del., 1969. 

Isostatic molding, 18 300 Isostatic refractory pressing, 21 504 Isostearic acid, physical properties, 5 35t Isotachophoresis, 9 738, 742, 748 Isotacticity, of polypropylene, 20 529 Isotactic PB resins, thermal properties of, 20 417... 

Isostatic molding — PTFE molding technique allowing uniform compression from all directions. It uses a flexible mold, which is filled with free-flowing granular powder. It is used for parts with complicated shapes. 

Isostatic compaction Powder encased in flexible mold is pressed equally from all directions by pressure transmitted to the mold by a liquid medium. Isostatic molding, isostatic pressing Hydrostatic molding chambers, automatic isostatic presses... 

FIGURE 13.41 Schematic of dry bag isostatic mold for an automotive spark plug. Radial normal stress is used to compress the powder against the metal conductor placed at the central axis of the mold. 

FORMING-The cooled mu is formed by extrusion [Pg.277]

For high strength and fine-grained materials, the calcination step is eliminated, the filler particles are reduced to the micrometer range, and isostatic molding at high pressures is substituted for conventional extrusion or molding. This limits the size of the product [to 250 mm (lOin.) diameter]. 

Isostatic molding is a suitable alternative to compression and automatic molding techniques for the production of PTFE parts with complex shapes in a wide range of sizes. Compression molding can supply a stock shape which can be machined to obtain the desired shape. The drawback to this option is the... 

Isostatic molding is ideal for manufacturing thin long objects from small tubes (5 mm diameter) to very large diameter thin wall tubes (30 cm diameter). Examples include pipe liners, liners for valves and fittings, flanged parts, closed end articles, and a host of other shapes which would require extensive machining. Table 5.3 offers examples of isostatically-molded parts and their applications. 

A drawback of isostatic molding is that the bag cannot produce sharp and perpendicular comers. Furthermore, the bag follows the contours of the resin particles and produces a less smooth surface than... 

Wet- and dry-bag are two techniques for isostatic molding which are principally identical but operationally different. The wet-bag process is similar to the basic molding procedure in which the mold is submerged in the pressurization fluid. In the dry-bag technique, the mold and the bag are fixed in place and the functions of the mold and the pressurization vessel are combined. The pressurization fluid is introduced through a high-pressure liquid supply system behind the flexible bag (Fig. 5.17). The mold assembly is designed to withstand this pressure. The term dry-bag contrasts the absence of submerged mold and wet mold assembly. 

Liner is made by either the ram extrusion process or the isostatic molding process. 

In the case of isostatic molding, the liner is inserted in the metallic piping by stretching it, after which the protruding lengths are flared over the flanges. 

Liners for fittings are made by isostatic molding and the metallic housing is inserted over the liner. Afterward, the metallic component pieces are welded to complete the fabrication. A fitting can also be used as a housing in which the lining is made isostatically. 

Lined pipe Isostatic molding, melt extrusion, paste extrusion PTFE, PVDF, PFA, ETFE, ECTFE... 

Dry Bag Isostatic Molding - A method producing parts from PTFE powder. The powder is compressed between a hard mandrel and an elastic bag in which the pressure is supplied by a fluid inside the annular space formed between an outer shell and the elastic bag. See also Wet Bag Isostatic Molding. 

Wet Bag Isostatic Molding - A method of isostatic molding in which polytetrafluoroethylene (PTFE) powder is compressed between a hard part and an elastic bag. The compaction is achieved by submerging the filled mold in fluid inside a high pressure vessel and pressurizing the vessel. See also Dry Bag Isostatic Molding, Isostatic Molding. 

---