Characterization of a reverse molding sequence at the mesoscale for in-mold assembly of revolute joints


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In-mold assembly and miniature molding have been combined to realize miniature assemblies. Our previous work has shown that for realizing in-mold assembly at the mesoscale, the molding sequence is the reverse of that used at the macroscale. Moreover, special features are needed in the mold to prevent plastic bending of the pin because of the pressure exerted by the second stage melt. This article presents novel mold designs and computational methods to enable the use of the reverse molding sequence to prevent: (1) plastic bending of the premolded component, and (2) joint jamming during the mesoscale in-mold assembly process. The computational methods are also validated through experimentation. Results reported in this article show that for making in-mold assembled revolute joints with the polymer combination of ABS and LDPE, a reversed molding sequence needs to be used for joints sizes less than 1.5 mm. POLYM. ENG. SCI., 50:1843–1852, 2010. © 2010 Society of Plastics Engineers