LFT-D Injection Molding Process Research And Mold Design

LFT-D(Long Fiber reinforced Thermoplastics Direct)is an online hybrid injection molding technology based on thermoplastic resin as matrix material and reinforced fiber as reinforcement material.This technology will be widely used in automotive lightweight applications in the future.Based on PA6(nylon 6)as the matrix resin,glass fiber as reinforcing fiber,through adjusting mixing temperature in the process of processing and molding temperature this parameter,to observe the mechanical impact of LFT-D process injection molding of long fiber thermoplastic composite materials of PA6 / GF,at the same time,its internal microstructure characterization,from microscopic structure and material properties to analyze the cause of affecting the material mechanics performance.Firstly,briefly introduce the background and research significance of LFT-D injection molding technology.The differences and advantages between LFT-D injection molding technology and LFT-G injection molding technology are compared.The research status and process flow of LFT-D injection molding technology are expounded.Then,the key factors about influencing the properties of long-fiber thermoplastic composites are introduced,and the corresponding testing methods such as DSC test,FTIR test,fiber orientation test,fiber average length test and so on are introduced.Secondly,according to the samples we need,a multi-mold was designed by UG software,including parting surface,plastic parts shrinkage,mold locking force check,mold selection and other aspects of validation analysis and design.Then,the overall assembly size of the designed mold is about 600mm×400×370mm.Finally,after designed the mold to determine the molding parameters and produce sample and material characterization,respectively from the critical length of the fiber length,fiber,fiber length distribution and fiber orientation degree,degree of interface combination between the Fiber and resin made microstructure characterization,and mechanical test of different batches of samples,also analyzed the degree of crystallinity of the samples,in the experiments we found:(1)in the process of sample preparation,the mixing degree of the sample increases with the increase of mixing temperature;The fiber length and fiber orientation can get better performance,which enhances the anisotropy of the sample.The variance of fiber length distribution decreased gradually,and the number of fibers below the critical length was reduced.(2)FTIR Fourier infrared spectrometer was used to test the processed samples.The interface bonding degree of PA+30%GF composite material samples molded by lft-d injection molding increased with the increase of mixing temperature.DSC differential calorimetry scanner was used to calculate that the crystallinity of composite materials decreased with the increase of mixing temperature.(3)From the perspective of the mechanical properties of composite materials,when the mixing temperature is 270℃,its mechanical properties are compared with other different batches,the bending strength and tensile strength are the best.While when the mixing temperature reaches 290℃,the impact toughness of the notched simply supported beam is the best.