The selection of linear guides is usually based on engineering practices. If a linear guide is used in conjunction with a ball screw, its specifications should be similar to the outer diameter of the ball screw. For example, if the nominal diameter of the ball screw is 20mm, choose a 20 gauge linear guide rail. The number of sliders is usually selected based on the load state or the designer's experience.

要注意的是：在选择直线导轨的精度等级的时候，请根据自身使用状况选用能够满足工程实际要求的导轨即可，不要无谓地提高精度等级加大制造装配难度和制造成本。下面，介绍一下其中相对重要的几个基本的概念。

It should be noted that when selecting the accuracy level of linear guide rails, please choose a guide rail that can meet the actual engineering requirements based on your own usage situation. Do not unnecessarily increase the difficulty and cost of manufacturing and assembly by increasing the accuracy level. Below, we will introduce several relatively important basic concepts.

基本静额定负荷：直线导轨在静止或者运动过程中如果承受过大的负载或者承受很大的冲击负载时，会导致导轨滚珠滑道的接触面和滚珠产生局部的的塑性变形，当这种变形量超过一定限度后，将会影响到直线导轨运行精度和平稳性。基本静额定负荷就是容许这种变形量的极限负荷。

Basic static rated load: If a linear guide rail is subjected to excessive load or impact load during stationary or moving processes, it will cause local permanent plastic deformation of the contact surface and balls of the guide rail ball slide. When this deformation exceeds a certain limit, it will affect the accuracy and stability of the linear guide rail operation. The basic static rated load is the ultimate load that allows for this amount of deformation.

国际通用的定义是：在负载的方向和大小不变的情况下，受到应力的接触面处，钢珠与滑道的变形量为钢珠直径万分之一时的静止载荷。所以，这个参数对于直线导轨来说是非常重要的，我们在使用过程中必须保证施加给直线导轨的静止载荷在允许范围内。通常，为了考虑其使用寿命和性，在使用时需要有一个系数来保证其正常使用的性和使用寿命，特别是在有冲击载荷时，这个数更要取得相对较大。普通的运行状态下通常取系数1.5 ≤ S ≤ 3，在有冲击载荷的时候通常3 ≤ S ≤ 5。

The internationally accepted definition is the static load at the contact surface where the maximum stress is applied, with the direction and magnitude of the load unchanged, when the permanent deformation between the steel ball and the slide is one thousandth of the diameter of the steel ball. So, this parameter is very important for the linear guide rail, and we must ensure that the maximum static load applied to the linear guide rail is within the allowable range during use. Usually, in order to consider its service life and safety, a safety factor is required during use to ensure its normal safety and service life, especially when there is an impact load, this safety factor needs to be relatively large. Under normal operating conditions, a safety factor of 1.5 ≤ S ≤ 3 is usually taken, and under impact loads, it is usually 3 ≤ S ≤ 5.

基本动额定负荷：在直线导轨的负荷大小和方向不变的情况下，直线导轨的额定寿命为 50km 时的负载。由定义可以知道，这个参数主要是为了计算和保证直线导轨的使用寿命的。这里我们给出滚珠直线导轨的额定寿命计算公式：

Basic dynamic rated load: The maximum load at which the rated life of a linear guide rail is 50km, while the load magnitude and direction remain unchanged. From the definition, it can be seen that this parameter is mainly used to calculate and ensure the service life of the linear guide rail. Here we provide the formula for calculating the rated life of the ball linear guide rail:

以上介绍滚珠丝杠传动系统选型计算完毕。

The selection and calculation of the ball screw transmission system mentioned above have been completed.

除此之外，利用同步带和齿轮齿条驱动负载直线运动的机构元器件选型计算与伺服电机基本类似，的区别：是同步带需要根据负载功率计算同步带的容量，齿轮齿条机构需要根据负载功率计算模数。其计算方法与大学教材《机械设计》中讲解的一致。关于具体元器件的负载能力、使用寿命等方面的参数，在使用过程中咨询相应的供应商即可。在此，无须赘述。需要强调的是：如果在实际使用中由伺服或者步进电机驱动则需要根据我们前面给出的惯量公式和扭矩公式进行相应的计算选择合适的启动扭矩。

In addition, the selection and calculation of components for the mechanism that uses synchronous belts and gear racks to drive load linear motion are basically similar to servo motors, with the only difference being that the synchronous belt needs to calculate the capacity of the synchronous belt based on load power, while the gear rack mechanism needs to calculate the modulus based on load power. The calculation method is consistent with the explanation in the university textbook "Mechanical Design". For specific parameters such as load capacity and service life of components, consult the corresponding supplier during use. Here, there is no need to elaborate further. It should be emphasized that if it is driven by a servo or stepper motor in practical use, it is necessary to calculate and select the appropriate starting torque based on the inertia formula and torque formula we provided earlier.