Precision Requirements For Linear Guide Design

(1) Guiding accuracy Guiding accuracy refers to the accuracy of the motion trajectory of the moving component when it moves along the linear guide bearing surface. The main factors affecting the guiding accuracy include the geometric accuracy of the guide bearing surface, the structural type of the guide, the contact accuracy of the guide pair, the surface roughness, the stiffness of the guide and the support, the oil film thickness and stiffness of the guide pair, and the thermal deformation of the guide and the support.

The geometric accuracy of the linear motion guide generally includes: the straightness in the vertical plane and the horizontal plane; the parallelism between the two guide surfaces. The geometric accuracy of the guide can be expressed as the error over the entire length of the guide or the error per unit length.

(2) Accuracy retention Accuracy retention refers to the ability of the linear guide to maintain the original geometric accuracy during operation. The accuracy retention of the guide mainly depends on the wear resistance of the guide and its dimensional stability. Wear resistance is related to factors such as the material matching, force, processing accuracy, lubrication method and performance of the protective device of the guide pair. In addition, the residual stress in the guide and its support will also affect the accuracy retention of the guide.

(3) Motion sensitivity and positioning accuracy Motion sensitivity refers to the minimum stroke that a moving component can achieve; positioning accuracy refers to the ability of a moving component to stop at a specified position as required. Motion sensitivity and positioning accuracy are related to factors such as the type of guide rail, friction characteristics, movement speed, transmission stiffness, and the mass of the moving component.

(4) Motion smoothness The motion smoothness of a linear guide refers to the performance of the guide rail without creeping when moving at low speed or in a small amount. Stability is related to factors such as the structure of the guide rail, the matching of the guide rail pair materials, the lubrication condition, the properties of the lubricant, and the stiffness of the transmission system of the guide rail movement.

(5) Vibration resistance and stability Vibration resistance refers to the ability of the guide rail pair to withstand forced vibration and impact, while stability refers to the performance of not experiencing self-excited vibration under given operating conditions.

(6) Stiffness The ability of the guide rail to resist deformation under force. Deformation will affect the relative position and guiding accuracy between components, which is particularly important for precision machinery and instruments. Linear guide deformation includes guide body deformation and guide pair contact deformation, both of which should be considered.

(7) Structural processability Structural processability refers to the difficulty of processing the linear guide pair (including the components where the guide pair is located). On the premise of meeting the design requirements, it should be as easy to manufacture and maintain as possible and low in cost.