Investigation of the effects of reinforcement particles in polymers on their grindability in single grit scratch test

Recently, polyether ether ketone (PEEK) and its particle-reinforced composites have found a special place in various industries due to their high strength-to-weight ratio, anti-allergic properties, high resistance to buckling, and other superior properties. These materials have widely been used in the aerospace and medical industries and are commonly finished in the final step through the grinding process. In this work, the single grain scratch test was performed to fundamentally study the grinding process and material removal mechanism of PEEK and its particle-reinforced composites. In this method, the material removal is realized by a single grit penetrating the workpiece. It was found that the amount of flowed or piled-up (side flow) materials around the scratch in the pure polymer is higher than the other two composites. Pure polymer with 2.5 J/mm3 and glass fiber-reinforced composite with 1.1 J/mm3 resulted in the highest and lowest specific energies, respectively. The specific energy of all three materials is reduced significantly by increasing the grit penetration depth, showing the significant role of the size effect in grinding these materials. The main reasons for the different results are the high heat transfer coefficient and higher strength of CFRP composite compared to PEEK and PEEK GF 30.