High precision components made of hard and brittle materials are increasingly in demand in many applications owing to the superior physical, mechanical, optical, or electronic properties offered by these materials. Mechanical machining, primarily milling, is the main shaping method used to achieve tight tolerances and high quality surface finishes on those hard materials, but excessive tool wear and poor surface integrity is a pressing challenge. Vibration assisted machining can significantly reduce cutting forces, enhance surface integrity and extend tool life, but the application of vibration assistance to milling has received little attention due to the complexity of kinematics and dynamics of this process. This paper investigates the kinematics of vibration assisted milling. Generic kinematic equations of vibration assisted milling are firstly formulated, and then three types of tool-workpiece separation mechanism is proposed and the requirements to realize each type of separation are discussed through kinematic analysis and simulation. Finally, an ABAQUS finite element model of vibration assisted milling is used to verify the proposed kinematic models and tool-workpiece separation types.