Towards predicting removal rate and surface roughness during grinding of optical materials

Lateral cracks during sliding indentation on various optical materials

“…From previous work, the lateral crack depth from static indentation follows a load dependence as described by Equation () (ie, scales as P 1/2 ) and hence can be described by the lateral crack slope ( s ℓ ) . Even though the scatter in the crack depth data from sliding indentation in Figure A does not warrant a quantitative load scaling, the lateral crack depth between static and sliding indentation are correlated for most workpieces.…”

“…First, this correlation suggests simple static indentation parameters can be effectively used to model and draw conclusions regarding more complex, dynamic processes involving sliding indentation such as grinding processes. In fact, this explains why previous grinding models utilizing static indentation behavior appear to do a reasonable job at predicting grinding behavior . Second, since it has been previously shown that lateral crack depth during static indentation scales as E 1 1/2 / H 1 of the workpiece material, this implies a similar scaling would apply for sliding indentation and hence grinding processes.…”

“…As discussed in the Introduction, various grinding characteristics (such as material removal rate, surface roughness, and sub‐surface mechanical damage) during optical fabrication have been shown to correlate with the characteristics and propensity of lateral cracks. Previous grinding models have quantitatively utilized the lateral crack material and load correlations (as measured by static Vickers indentation) with good success . The results shown in Figure , which illustrates that static and sliding indentation lateral crack depth behavior are directly correlated, have some important implications with respect to understanding and predicting grinding processes.…”

“…Recent studies have quantitatively described grinding characteristics such as material removal rate, surface roughness, and even sub‐surface mechanical damage as a function of the lateral crack scaling parameters s ℓ and/or E 1 1/2 /H 1. However, the fracturing that occurs during grinding processes is from sliding and rolling processes which are significantly more complex compared with static indentation. Some key differences, include different stress distributions, different loading times, overlapping stress distributions between neighboring abrasive particles, overlapping fracture effects, friction forces, and plastic material ploughing.…”

“…Some key differences, include different stress distributions, different loading times, overlapping stress distributions between neighboring abrasive particles, overlapping fracture effects, friction forces, and plastic material ploughing. In addition, grinding can involve loading from various abrasive types including sharp particles (eg, fixed diamond abrasives) or blunt particles (eg, loose abrasive alumina particles) …”