Thermoform matched mold

Injection Molding Extrusion Blow Molding Thermoforming Reaction Injection Molding Rotational Molding Compression and Transfer Molding Matched Mold Spray-up... 

In matched-mold forming, a heated sheet is placed between a matched female and male mold parts. As the two mold halves close, they distort the sheet to their shape. The air between the mold halves is removed. The article walls are more uniform than for many of the thermoforming techniques. This technique is used for the production of foamed PS and foamed polyolefins food containers. 

Figure 8-8. Schematic of thermoforming process using matching molds.

This is another version of cold forming by utilizing a thermoformed plastic skin to impart an excellent surface and other characteristics (for weather resistance, etc.) to a cold-molded RP. For example, a TP sheet is placed in a matched mold cavity with an RP uncured material placed against the sheet. The mold is closed and the fast, room temperature curing plastic system hardens. The finished product has a smooth TP-formed sheet backed-up with RP. 

In matched mold thermoforming (Fig. 10.9), matched sets of negative and positive molds are used to form the part from the softened sheet. Vacuum is generally applied through the negative cavity, as well. The result is excellent dimensional control, and the ability to form very complex shapes. This method is most often used in thermoforming of foams, due to their tendency to deform if not restrained. 

Figure 10.9 Matched mold thermoforming (reprinted with permission from [1])...

Various mechanical techniques have been developed for thermoforming that use neither air pressure nor vacuum. Typical of these is matched mold forming (Figure 2.41). A male mold is mounted on... 

A combination of matched molding and thermoforming has been found successful with some high-performance parts. The material (fabric-reinforced PPS laminate) is heated to 316C (600P) in an infrared oven and then rapidly transferred to the mold. A seal is made... 

Fig. 11.7 Process of composite preparation a fiber soaking, b disintegration and mixing with polymer fibers, c wet-forming, d heating, e match-mold, thermoforming, and f formed composite [29]...

Matched mold forming is a thermoforming process in which matched molds are used to assure a contained, defined part. Foamed PS egg cartons are a product example. See TJiermoforming. 

The types of thermoforming processes are vacuum forming, pressure forming, melt phase thermoforming, and matched mold forming. Examples of applications of thermoformed parts are ... 

Matched-mold thermoforming n. A sheetthermoforming process in which the heated plastic sheet is shaped between male and female halves of a matched mold. The molds may be of metal or inexpensive materials such as plaster, wood, epoxy resin, etc., and must be vented to permit the escape of air as the mold closes. 

Particulate-filled thermoplastic polyolefins are used in vehicle applications. Talc, calcium carbonate, and kaolin are typical fillers. Fillers do not change the transition characteristics of the plastic. Fillers increase the temperature-dependent elastic moduli of the plastics, increasing the forces required to form the plastics in the plateau-temperature regions. Matched-mold thermoforming is necessary if the product cannot be formed using a conventional pressme box over a single-surface mold. 

Again, matched-mold thermoforming is recommended. Long- and continuous-fiber-reinforced thermoplastics pose an additional processing problem. Alliiough the reinforced sheet can be drawn into shallow shapes using matched-mold pressure forming, fibers are inextensible. As a result, products will exhibit resin-rich and resin-poor areas. Nonuniformity in reinforcement implies nonuniformity in physical properties across the product. 

Fig. 19.44. Thermoforming with matched molds. Heated sheet may be clamped over the female mold or draped over the male mold. The mold is closed, forming the sheet between the male and female parts. Mold vents allow trapped air to escape. Courtesy Modern Plastics Encyclopedia, 1989.)...

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