Study On High-Speed Dynamic Behavior Of Super-Thin Dicing Blades And Design Of A New Bond

Super-thin dicing blades are used in electronic chips,optics,communications and other precision manufacturing industries.They are made of diamond/cBN and bond through mixing,pressing,sintering,finishing and other processes.As size of chips shrinks,precision of components is harsher and intelligence of industry is promoted,thickness of blades become thinner?0.04 mm?,rotational speed becomes higher?50000 rpm?,feed speed becomes faster?300 mm/s?.The dynamic properties of blades are more important when dynamic factors are gradually prominent.Properties of bond have a great influence on the dynamic properties of blades.So,it will inevitably put forward higher requirements on the performance of bond,such as higher strength and young's modulus,appropriate hardness,better thermal stability and fatigue resistance ability.As the linear velocity increases and precision of components improves,it becomes more important to study dynamic behaviors of super-thin dicing blades.In this paper,dynamic effects are introduced during the study of high speed dicing.At the same time concepts of dynamic diameter and dynamic hardness are proposed.Functional relations between dynamic behaviors such as dynamic diameter,strain rate and parameters of bond including elastic modulus,density and Poisson's ratio are established.Variation trend of strain rate and dynamic diameter on the precision and critical speed are studied,which can guide the development of new bonds.Effects of hardening,heating and ductile-brittle transition caused by high strain rates are studied with infrared test,Hopkinson pressure bar,Nano-indentation and high speed dicing test.Research shows that dynamic diameter,which has the most obvious influence on the machining accuracy,decreases with the increase of the elastic modulus of the bond density,rotational speed and static diameter.During the high-speed dicing,strain rate of materials increases as linear velocity increases,and decreases as elastic modulus increases.When the linear velocity of blades is 151.77 m/s,the strain rate can reach 6.65×10⁵ s^-1.High-speed grinding brings about high strain rate,which further causes hardening,heating,deformation and ductile-brittle transition of materials,so there is a critical value of linear speed for dynamic performance change.The critical speed of processing quartz with ultra-thin dicing blades is 60.71 m/s.As machining precision and production efficiency are improved,traditional bonds can't meet needs of industry.As a new concept of designing materials,high entropy alloys have a wide range of density adjustment,high elastic modulus and hardness.Based on dynamic behavior,thermodynamics,density,diamond graphitization temperature,elastic modulus,the high entropy alloy bond of CuZnFeTiAl is designed.Entropy of mixing,enthalpy of mixing,difference of atomic radius,and other calculated results of thermodynamics and topology show that the solid solution phase of the high entropy alloy can exist stably.The CuZnFeTiAl high entropy alloy is prepared by mechanical alloying,and its phase structure,microstructure,particle size composition,bulk density and oxygen content are characterized.Results shows that the CuZnFeTiAl high entropy alloy's optimum mechanical alloying time is 40 h,the apparent density of powder is 1.8 g/cm³,and the particle diameter of D10 and D50 is 2.4?m and 9.4?m respectively,its phase structure mainly is BCC.The sintered body of high entropy alloy under 850°C has good mechanical properties,thermal stability and elastic modulus.The elastic modulus is 80%higher than that of traditional metal bond,and its density is 28%lower than that of traditional bond.It has better strain rate sensitivity.When the strain rate increases from958 s^-1 to 1316 s^-1,the yield strength increases from 1578 MPa to 1720 MPa.With the increase of loading rate from 500?N/s to 2500?N/s,the dynamic hardness of sintered body increased from 12.35 GPa to 14.21 GPa.High-speed grinding results shows that arc radius,wear,dynamic diameter and face runout decrease as the content of CuZnFeTiAl high entropy alloy bond increases in the range of 0⁶0 wt.%.The CuZnFeTiAl high entropy alloy bond has high elastic modulus and bonding strength,good rigidity and strong resistance to high temperature.It not only reacts with diamond to form TiC,but also reacts with cBN to form TiN and TiB₂.It has a great application value and potential in the high-speed grinding field.