Mold-cavity cost

Liquid-Injection Molding. In Hquid-injection mol ding (LIM), monomers and oligomers are injected into a mold cavity where a rapid polymerization takes place to produce a thermoset article. Advantages of these processes are low cost, low pressure requirement, and flexibiHty in mold configuration. Conventional systems, such as isocyanate with polyol, release Htfle or no volatiles. The generation of substantial volatiles in the mold is obviously undesirable and has represented a significant obstacle to the development of a phenoHc-based LIM system. A phenoHc LIM system based on an... 

In this process, resin is injected into a closed mold containing the reinforcement preform. The resin can be injected either under pressure [22] or under vacuum [23]. The potential advantages of this process are (I) low mold cost, (2) inserts can be incorporated, (3) low pressure requirements, (4) accurate fiber orientation, (5) automation possibilities, and (6) versatility. The resin formulation and process variables are selected so that no significant polymerization occurs until the mold cavity has been completely filled. This is achieved by the ad-... 

Using low cost material to meet high performance requirements will compromise their integrity. As an example, the cost of a mold cavity and core materials, for more than 90% of the molds, is less than 5% of the total mold cost. Thus it does not make sense to compromise mold integrity to save a few... 

Metal molds and cores are used in permanent mold casting. The process works best in continuous operation so that the mold temperature can be maintained within a fixed operating range. The operating temperature of the mold is one of the most important factors in successful permanent mold casting. Mold cavities are machined from solid blocks of graphite. Mold life is the major cost factor in permanent mold casting. 

Permanent mold casting is generally similar to die casting, except that gravity rather than pressure is used to fill the mold cavity. This process is employed where larger, or heavier, section castings are needed. Mold costs are still high, so this process is economical only in volume as well. 

Reaction injection molding (RIM) is a fast, low-pressure, low-temperature, low-cost process for one-step conversion of reactive liquids into large finished solid plastic products. Liquid polyol and liquid diisocyanate are mixed by impingement, pumped instantly to fill a large mold cavity, and polymerize/ cure rapidly to form a thermoset polyurethane product. The cured polymer may be a stiffly flexible product such as automotive bumper covers, front ends, and trim or a rigid foamed product such as furniture and housings (cabinets) for computers, business machines, TY and radio. 

Spin casting can use plastic molds, such as silicone, to produce close tolerance, highly cost effective, limited production in a variety of materials. The process uses easily adjustable centrifugal force to inject liquid thermoset plastics into a circular disc-shaped elastomeric mold under pressure, completely and rapidly filling the mold cavities. 

Only one machine is required to do bodi molding and blowing, easier quality control, since each molding cavity corresponds to a specific blow cavity, and lower installation cost of total setup. 

TYPE PERCENTAGE USED WITH IMM NO. OF MOLD CAVITIES PART SIZE COST/UNIT DOLLARS... 

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