Purpose Since robot’s structural stiffness is usually less than 1 N/µm, mode coupling chatter occurs frequently during robotic milling process, and chatter frequency is close to the natural frequency of the robot itself. Chatter not only affects the surface quality but also damages the robot and reduces the positioning accuracy. Therefore, it is necessary to predict chatter in robotic machining process. Design/methodology/approach A three-dimensional dynamic model for robot’s spatial milling plane is established, and a corresponding stability criterion is obtained. First, the cutting force in milling plane is transformed into the coordinate system of the robot principal stiffness direction based on homogeneous transformation matrix. Then the three-dimensional stability criterion under milling process can be obtained by using system stability analysis. Furthermore, the circle diagram of mode coupling chatter stability is drawn. Each feeding direction’s stability under the two processing forms, referred as spindle vertical milling and spindle horizontal milling, is analyzed. Findings The experimental results verify that the three-dimensional stability criterion can avoid chatter by selecting machining feed direction in stable area. Originality/value This paper established a three-dimensional dynamic model in robot’s spatial milling plane and proposed a three-dimensional stability criterion according to the Routh criterion. The work is also expected to be an efficient tool in the development of robotic milling technology.

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This study concerns the importance of curing kinetic models for the prediction accuracy of the thermal overshoot in the curing process of thick polymeric composite plates. An adaptive activation energy (AAE) method was proposed to determine an accurate curing kinetic model with adaptive activation energy (CK‐AAE). Then the temperature field model of the autoclave curing process was established based on the CK‐AAE equations for predicting the curing thermal overshoot of thick polymer‐matrix composite plates. The prediction accuracy of the curing degree using the CK‐AAE model was improved greatly compared with the common curing kinetic models. And the predicted curing thermal overshoot of thick polymeric composite plates yielded good agreement with the measured results from the autoclave curing experiments. Moreover, it was observed that the curing thermal overshoot was more susceptible to the laminate thickness and less affected by the stacking sequence.