Browse Publications Technical Papers 2002-01-2036
2002-07-09

A Novel, New Direct Injection Technology for In-Line Compounding and Molding of LFT Automotive Structures 2002-01-2036

In-line compounding and molding is the low-cost technology for producing long fiber reinforced thermoplastic (LFT) composite parts. Composite Products, Inc. has been using this technology since 1991 to produce a variety of automotive parts, including front-end supports, seat bases, and interior trim panels. In the upcoming year, many new applications for LFTs will be seen in both the European and North American markets. This paper provides a brief overview of the in-line compounding and molding technology for those who are not familiar with it.
The in-line compounding and molding technology marries two processes that are not ideally suited to each other. Compounding, on one hand, is a continuous process, producing a constant output of molten LFT material measured in kilograms per hour. Molding, on the other hand, is a cyclic process, producing a part in a regularly defined cycle time measured in seconds. Marrying a continuous process with a cyclic process requires a certain amount of ingenuity. In this case, it requires a piece of process equipment called an “accumulator.”
A traditional accumulator is simply a reservoir where molten LFT material can be stored for a short time between cycles of the molding press. In its simplest form, it is an insulated piston and cylinder with shut-off valve controlling the input and a guillotine knife controlling the output. CPI has developed and patented a totally new technology that will be discussed publicly for the first time at this presentation. This improved technology combines the function of the piston with that of a check valve. This new “accumulator” permits direct injection of LFTs into traditional injection molds. This new “shooter” technology vastly increases the number of applications that can be made by in-line compounding and molding while reducing costs and improving performance.

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