Pulsed Laser Profiling of Grinding Wheels at Normal and Quasi-Tangential Incidence

A new methodology for normal and quasi-tangential pulsed laser profiling of grinding wheels is proposed, with laser path planning calculated according to a pre-specified angle of incidence and radial laser progression or predicted single-pass incision depth. Though tangential laser profiling has previously been investigated, few works have addressed the issue of negligible laser absorption under these conditions other than to apply a focal offset that effectively reduces the angle of incidence below 90∘. In the present work, the angle of incidence is specified explicitly, with normal and quasi-tangential profiling experiments performed on rotating bronze-bonded diamond and porous aluminum oxide grinding wheels with a 1064 nm nanosecond pulsed fiber laser source with 20 W average power. Triangular incisions are cut into each sample, following which analyses are performed with an optical profiler operating in confocal mode and x-ray computed tomography to determine the material removal rate and profile accuracy under all tested conditions. The angle of laser incidence is found to be of particular relevance to profiling operations, with more than one order of magnitude difference in material removal rates observed between 70∘ and 80∘ incidence, with improved profile accuracy in the latter case. Specifically, material removal rates of 0.12−0.14 mm 3/s, 0.075−0.1 mm 3/s and 0.002 mm 3/s are achieved at normal, 70∘ and 80∘ laser incidence, respectively, for bronze-bonded diamond, and 0.1 mm 3/s is achieved at 70∘ incidence for porous aluminum oxide. For both materials, profile accuracy of 50−70 μm is achieved under optimum conditions. The presented results highlight the necessity for precise specification and control of the angle of incidence during laser profiling operations. They furthermore confirm that laser profiling of grinding wheels is a viable alternative to electrical discharge machining for bronze-bonded diamond grinding wheels and a potential complementary process to hard-on-hard abrasion for ceramics.