Research On Machinability And MR Compatibility Of Engineering Materials

Operation accuracy, equipment life, the magnetic resonance (MR) image quality,safety of the patients and the surgical devices will be influenced by the materials thatare used to manufacture the magnetic resonance imaging (MRI) guided robot. Thispaper focuses on the evaluation theory of material machinability, mechanistic forcemodeling and MR safety and compatibility based on the MRI-guided surgical robot.Theoretical analysis is completed and experiments are designed to validate theprecision of the theory. The main work and the gained results are summarized intothree aspects and listed below:Firstly, due to the importance of material machinability to the MRI-guided robot,the methods that can be applied to evaluate machinability are introduced and thetheoretical formula is established based on the previous study. Milling experimentsare done to test the quantitative value of the factors that are used to evaluatemachinability in the theoretical system. Based on the theoretical and experimentalresults, the ranks of the candidate materials’ machinability are obtained.Polyformaldehyde is the best.Secondly, the mechanism of milling process is analyzed. The variation of uncutchip, the shear mechanism of the rake face, the rubbing and ploughing effects of therank flutes combined with the cut mechanism of the chisel edge are studied. Themechanistic force model is acquired synthesizing the previous analysis. Millingexperiments are conducted to validate the model and it is found that the deviation isbelow10%.Finally, MR safety and compatibility of materials are analyzed in three aspects:theory, simulation and experiment. The interaction between material and the magneticfield is studied and typical factors that impose on MR compatibility are studied.Simulations are dependent on theoretical results and then extended to a broader scopeto test the factors that influence MR compatibility. Based on theoretical andsimulation results, experiments are implemented to test the candidate materials.Compatibility of engineering plastics is the best. Then the material that is to be usedto manufacture the MRI-guided robot is selected based on the machinability and safety&compatibility analysis. Polyformaldehyde will be used to manufacture therobot.