Self-optimization of the V/P switchover and packing pressure for online viscosity compensation during injection molding

Injection molding (IM) is one of the essential forming methods for thermoplastic polymers, which is widely used in modern industries such as automobiles, electronics, and medical industries. At present, the machine parameters of the IM machine (IMM) have achieved sufficient high control accuracy and repeatability. However, the viscosity of thermoplastic melt is still easily influenced by the external environment, such as the fluctuations in batches, the compounding in recycled materials, and so on. Conventional IM equipment cannot sense and conduct adjustments correctly, which leads to the production of rejects. A real-time monitoring and controlling model employed for viscosity compensation was established in this article, which could monitor viscosity fluctuations and implement self-adjustment in the IM process. Three kinds of polypropylenes (PP) with different viscosity and materials with different percentages of recycled pellets were randomly added into the barrel for comparison. The results revealed that the pressure integral relative to time is able to monitor the melt viscosity and illustrate the IMM to optimize the V/P switchover and packing pressure in the current molding cycle. The part weight could achieve a higher stability and the model could bring about a decrease in weight fluctuations of 50% to 70%. KEYWORDS injection molding, self-optimization, viscosity compensation, weight fluctuation
1 | INTRODUCTION Injection molding machines (IMMs) are common equipment to form polymer materials. [1-3] More than 30% of plastic parts are molded by the IM process. [4,5] The repeatability [...]