Cylinder linings of lightweight combustion engine blocks made from aluminium cast alloys are typically coated with thermally sprayed layers to enhance the chemical resistance. Finish machining of the cylinder linings is currently done by honing. A substitution of this process by machining with geometrically defined cutting edges would have significant advantages, especially concerning ecological aspects. For the investigations Fe17Cr2Ni0.2C iron based coatings applicated by atmospheric plasma spraying on substrates, prepared with a dovetail microstructure are machined by turning. In the experiments the feed is varied in the range of 0.025 mm to 0.15 mm. The tools used comprise CBN tips involving a rake angle of 0°. Tool wear and machining forces are determined. The geometrical properties of the machined surfaces are detected by tactile measurements, 3D laser scanning microscopy and SEM. The residual stresses are characterised by XRD. An increase of the feed results in increasing components of the resultant machining force and higher values for Ra, Rz, Rpk, Rk and Rvk. Additionally, the amount of opened pores and pulled out coating material is reduced for high feeds. By increasing the feed the absolute values of the compressive principle stresses decrease. The increase of the knowledge in machining of thermally sprayed coatings by tools with defined cutting edges contributes to a substitution of the honing process and hence enables a more material and energy efficient production.
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