A model for predicting surface roughness in single-point diamond turning

• The relative tool-work vibration is extracted from the machined surface profile and thus is more credible.
• The swelling effect is quantified and first taken into account in predicting surface roughness.
• Material property and spindle speed have dominant influence on relative tool-work vibration and swelling effect.
• A prediction model of surface roughness containing relative tool-work vibration and swelling effect is proposed.
• The model proposed shows a higher predicting accuracy as compared to previous models.

The relative tool-work vibration is not generalized enough to represent the actual displacement between tool and workpiece in previous prediction models. This is due to the fact that the vibration was assumed as a steady simple harmonic motion and was only measured before turning process. In this study, an improved method is presented to evaluate the actual relative tool-work vibration. By using this method the vibration information obtained is more credible, as it contains the components caused by machine tool error, cutting force, material property and changing of cutting parameters. Moreover, the swelling effect is analyzed using a new evaluating method and taken into account for predicting surface roughness. On the basis of analyzing both the relative vibration and the swelling effect, a model is proposed for predicting surface roughness Ra in single point diamond turning. Prediction results prove that this model is a closer approximation of the actual turning process as compared to the previous models and shows a higher predicting accuracy of surface roughness.

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