Study On The Compact Density And Sintering Deformation Of Carbide Inserts

Die pressing forming, which applied in manufacturing NC inserts with WC-Co powder as the substrate material, is the main method to produce compacts. However, non-uniform density distribution resulted in deformation of compact in sintering process as structure of NC insert and the feature of die pressing forming. At present, the method of modifying the moulds repeatedly is used to ensure the accuracy of NC insert compacts. With the rapid development of numerical simulation technology, through the simulation of pressing process, finite element simulation of WC-Co powder in pressing process is the effective method to optimize the mould design so as to dramatically reduce the cycle of mould design, heighten the efficiency and reduce costs.Based on the theory of powder forming, WC-Co powder mathematical model for simulation was established. It found that the density distribution from theoretical calculation is the same with the actual pressing deformation from the analysis on the difference of compact density under the different pressing parameter using MSC.Marc. This result confirms the accuracy of simulation method and offers the basis for drafting technology of the pressing parameter. Orthogonal tests of V and D-shaped inserts were researched to find out the main effect of the relative density distribution on blade angle and arc. The simulation results show that arc is more sensitive than blade angle to the deformation of compact.The relationship between the density and the deformation of compact was deduced via combining the physical test and theoretical calculation method. Pressing physical tests were used to fabricate a group of cylindrical compacts with different height, which keep the loading height of WC-Co powder unchanged, while change the pressing height. Meanwhile, the same physical tests were simulated by FES software MSC.Marc and relative density of each compact model was calculated. Finally, the relationship expression between density contrast and height difference of powder was built, which shows that the deformation value from the formula is similar to the actual deformation. Therefore, the formula provides a theoretic basis of optimizing mould design in future.