Experimental Study And Quality Prediction Of Injection Molding Process Of Micro-fluidic Chip

Conventional injection molding process and its theory have been matured, now the studying on micro injection molding theory and process has been become particularly important, with the needs of scientific and technological development for micro injection molding parts and the development of micro-injection molding. These are the key problems that how to solve the molding defects and establish a kind of systematic process specification.Then the micro-fluidic chip, which is a kind of typical plastic parts with micro-structure in micro injection molding, was chosen as the subject. The injection molding process of micro-fluidic chip involves with traditional and micro injection molding. This paper pays emphatic attention on the defect improvements of the micro-fluidic chip molding, which involves incomplete duplication, surface crinkle, flash and warpage. Firstly the molding process for two kinds of micro-fluidic chip with micro-channel of widths 50μm and 70μm was studied. Then the injection molding specification for micro-fluidic chip molding is desgined by taking advantage of structural improvement of the mold, numerous experiments and theoretical analysis, and coming up with the solutions to the molding defects, especially the enchancement of the copy for mico-channel.Secondly, with regarding to the other kinds of micro-fluidic chips with diverse width of the mico-channel, the molds were designed accordingly. Then, based on the injection molding specification, the orthogonal experiments for three sets of micro-fluidic chips (with widths of 30μm,80μm and 100μm, respectively) had been done to find the influence(mold temperature, holding time, cooling time, injection pressure) on the molding quanlity, which further justifies the feasibility of the injection molding specification to the micro-fluidic chip molding.Thirdly, the qualified products were obtained with the application of the injection molding moldinging specification, while the bonding work was greatly decreased by using the core pulling structure of stationary mold to mold the pool structure directly on the cover plate and the mold of substrate plate integrated with cover plate was designed and manufactured.Then, decision tree classification method was applied to obtain the decision tree training samples and test samples, taking process parameters(mold temperature, holding time, cooling time, injection pressure) as the input, and the width of micro-channel as the output. Through C&R Tree in the SPSS to train and test the model, until the fitting precision was reached the requirement. Fewer errors were made comparing forecast results with the experimental data. and it is justified the decision tree classification method can be workable.The hot runner technology had been applied in molding the microfluidic chip too. From molding tests, the high-quality micro-fluidic chips can be achieved under the same parameters. Furthermore, the experimental results show advantages, such as:low pressure loss, high molding quality but material and time saving.In a word, the injection molding process specification can be used to guide the actual producing of micro-fluidic chip.