Molding TV cabinets for automated assembly

Not every molder in Tijuana, Mexico is affiliated with a U.S. company. In fact, Japanese electronics firms are increasingly finding the location desirable for their operations. As these OEMs open maquiladora plants, their suppliers have followed suit. Meiki, a leading Japanese custom molder, has partnered with JVC (The Victor Company of Japan) to open a new manufacturing site in Tijuana. JVC already has its own facility there and hopes to streamline its production process by partnering with Meiki, whose separate facility is dedicated to molding a variety of TV cabinets-from 13 to 36 inches-for JVC. Rather than being simply a tale of international business, the real story here is how JVC and Meiki did some upfront engineering to ensure the cabinets could withstand automation, both on the molding floor and on the assembly line.

According to Masaru Matsuzawa, engineering manager for JVC, initial designs for the cabinets are created at headquarters in Yokohama, Japan. Moldfilling analysis is performed prior to cutting tool steel to determine optimum gate size and wall thickness. Because the cabinets are molded with gas-assist, designers also do simulations in order to understand the potential response of different materials under consideration; then they compare the results with actual molded parts.

Meiki produces both the tooling and parts for this project. The molding operation uses six Mitsubishi and Toshiba presses, ranging from 220 to 1600 tons, to produce the various cabinet sizes. Several models are molded in PS (Avantra ES8550 from BASF Polystyrenes) for its high-impact and flame retardant capabilities. JVC general manager Henry Nagaoka explains, "Together with Meiki, we chose this material for its flow rate and low outgassing to cut down on tool deposits and the resulting maintenance. In addition, the material is flame retardant, needed to meet UL requirements, without using decabrominated compounds."

And, Nagaoka adds, the cabinets have additional demands. After Meiki molds them, they are sent to the JVC assembly facility, where automated robots with suction cups lift the partially and fully assembled televisions from one station to the next. The front cabinet and back cover are also assembled using a high-speed, robotic fastening machine. Forces from these automated devices can crack the cabinet if it doesn't have sufficient strength. Robotic suction cups cannot adhere to form an airtight seal if the surface is not sufficiently smooth, and the robot will drop the TV.

Recognizing these potential dangers, JVC and Meiki designed both parts and tools to compensate. For instance, during simulation and before molds are cut, they perform a strength simulation as well as a drop test and vibration test. Because wall thickness determines overall strength, the two groups pooled their knowledge of gas-assist to optimize wall sections. The 27 inch cabinet is 2.3 mm thick, arrived at through the engineers' combined experience in molding. Adding ribs to improve structural rigidity was less of an option because more ribs meant more process complexity. "We made every effort to make the cabinet strong enough to withstand assembly equipment without additional ribs," Matsuzawa says.