Double face grinding with planetary kinematics of a Ni-Mn-Ga alloy with magnetic shape memory effect

Magnetic shape memory (MSM) alloy actuators, such as Ni-Mn-Ga, require extremely flat and smooth surfaces to function reliably. However, these materials are challenging to finish due to their sensitivity to machining-induced stress σ and heat q. This study demonstrates that double face grinding with planetary kinematics (DFG-P) can produce high-quality surfaces on Ni-Mn-Ga actuator sticks. The actuator sticks were ground under varying process forces FP and kinematics. By limiting the effective process force per stick FP,AS ≤ 5 N and optimizing the rotational speed of the grinding wheels ngw, crack-free surfaces with sub-micron mean roughness depth Rz were achieved. The plane parallelism P was enhanced by over 90 % and the mean roughness depth Rz ≈ 0.3 µm was obtained using a fine diamond grinding wheel with a grain size dg = 6 µm. Approximately 60 % of the actuator sticks remained completely intact under optimal conditions, whereas higher process forces FP led to edge chipping and cracks. These results underline the potential of DFG-P as a superior finishing method for MSM actuators, enabling scalable production of precision components.