SCIENCE AND TECHNOLOGY ENGLIAH FOR MECHANICAL ENGINEERING 2. Machining accuracy of relative positions between part surfaces Accuracy of dimensions between part parallelism 平行度 surfaces(for example, the distance between two parallel planes or the centers of two holes, etc.) perpendicularity 垂直度 Accuracy of positional relations between part surfaces(for example, the parallelism and surface roughness perpendicularity of two planes or two axes, etc.) 表面粗糙度 The surface quality of a part indicates the surface characteristics of the part. It includes either geometrical or physic-mechanical parameters, which are listed below D Surface roughness 2) Physic-mechanical state of surface layerSCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING 2. Machining accuracy of relative positions between part surfaces. - Accuracy of dimensions between part surfaces (for example, the distance between two parallel planes or the centers of two holes, etc.). - Accuracy of positional relations between part surfaces (for example, the parallelism and perpendicularity of two planes or two axes, etc.). The surface quality of a part indicates the surface characteristics of the part. It includes either geometrical or physic-mechanical parameters, which are listed below: l) Surface roughness. 2) Physic-mechanical state of surface layer. parallelism 平行度 perpendicularity 垂直度 surface roughness 表面粗糙度